Title of Invention	AN APPARATUS AND A METHOD FOR LOADING AND HOLDING HOT OPTICAL FIBER PREFORM AND PRECURSORS THEREOF
Abstract	A novel mechanism for holding hot optical fiber preform and precursors thereof is disclosed. The present invention solves the problem of holding hot optical fiber preform 5 and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from 10 one stage to another without manual intervention.

Title of Invention

AN APPARATUS AND A METHOD FOR LOADING AND HOLDING HOT OPTICAL FIBER PREFORM AND PRECURSORS THEREOF

Abstract

A novel mechanism for holding hot optical fiber preform and precursors thereof is disclosed. The present invention solves the problem of holding hot optical fiber preform 5 and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from 10 one stage to another without manual intervention.

Full Text	FORM 2 The Patent Act 1970 (39 of 1970) & The Patent Rules, 2005 COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13) TITLE OF THE INVENTION "A NOVEL MECHANISM FOR LOADING AND HOLDING HOT OPTICAL FIBER PREFORM AND PRECURSORS THEREOF." APPLICANTS: Name : Sterlite Optical Technologies Ltd Nationality : Indian (A Company Registered under Indian Companies Act) Address : El, E2, E3, MIDC, Waluj, Aurangabad, INDIA - 431136, The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:- 1 Agent Docket No: BL/PAT/IN/085/001 Field of the Invention: The present invention relates to a novel mechanism for loading and holding hot optical fiber preform and precursors thereof. Particularly, the present invention relates to 5 a novel mechanism for loading and holding hot optical fiber preform and precursors thereof, capable of loading and holding bulky optical fiber preform and precursors thereof reducing overall manufacturing time and making the transportation of optical fiber preform and precursors thereof simple and safe. 10 Background of Invention: The role of Optical fibers has become significant in the field of communications. There has been a momentous increase in usage of optical fibers. It is expected that the use of optical fibers in local loop telephone and cable TV service will increase in order to 15 deliver greater amount of information in the form of data, audio, and video signals to residential and commercial users. Optical fiber comprise a core and a cladding surrounding the core. The refractive index of core is higher as compared with the refractive index of the cladding in order to 20 achieve light transmission inside the optical fiber, by the phenomena known as total internal reflection. Generally, either the refractive index of the core is substantially uniform across its diameter (also called step index optical fiber) or the refractive index of the core has a maximum at the center and decrease in parabolic fashion near the periphery (also called graded index optical fiber). Any other geometric shape and profile 25 of the refractive index of the core is possible catering to a particular need. It is desirable that the manufacturing process of the optical fiber preform and precursors thereof to be economical in order to support the increasing demand of optical fiber and that too at low cost, meaning thereby, it is necessary to improve the production 30 efficiency of the optical fiber manufacturing process. Reducing the manufacturing time can enhance the production efficiency of the optical fiber preform and precursors 2 Agent Docket No: BL/PAT/IN/085/001 manufacturing process, which in turn means that it is necessary to reduce the optical fiber preform and precursors manufacturing process time as much as possible. In batch type manufacturing, the optical fiber is obtained by drawing optical fiber 5 preform. The optical fiber preform is an enlarged image of optical fiber, which like the optical fiber comprises a central core portion and an outer cladding. The core portion comprises the core and a part of cladding of the fiber preform. The core portion of the optical fiber preform can be prepared by any known methods, for example, by Atmospheric Chemical Vapor Deposition (ACVD) method, wherein the soot is deposited 10 during the deposition process step on the cylindrical member (also referred as target rod or mandrel) with a hollow glass handle intact, used for ease of handling the soot porous body so formed. In this method, the soot deposition is accomplished by traverse motion of the cylindrical member over the burners or vice versa while rotating the cylindrical member. The burners are supplied with silicon containing materials (for example silicon 15 tetrachloride), gases supporting oxidation (for example oxygen) and heat producing gases (for example hydrogen, methane etc). The oxidation of silicon containing materials takes place resulting in the formation of oxides of silicon, which is generally referred to as soot. The initial soot deposition comprises dopant chemicals (for example germanium tetrachloride) to increase refractive index of the core and dopant chemicals are terminated 20 after desired core diameter is obtained. The deposition process continues until the required dimension of the soot porous body is attained for meeting desired core diameter in the optical fiber preform and the desired core-clad diameter ratio in the fiber. After completion of soot deposition and on cooling the soot porous body to room temperature, the cylindrical member is removed from the soot porous body, to form hollow cylindrical 25 soot porous body defining a capillary at the center [herein after referred to as hollow soot porous body]. The hollow soot porous body so formed by the ACVD method contains large amount of hydroxyl group or water as generally referred to. In order to remove the hydroxyl content of the hollow soot porous body, it is treated with gases, which chemically reacts with the hydroxyl group. Halogens or compounds of halogen are 30 generally used for such purpose. This step of removing the hydroxyl content from the hollow soot porous body is known as dehydration or drying. In this step of dehydration or 3 Agent Docket No: BL/PAT/IN/085/001 drying at first a glass plug is inserted into the end remote from the handle of the hollow soot porous body. The cooled hollow soot porous body is moved into a furnace, suspended by the hollow handle in the furnace, wherein this hollow soot porous body is heated at a temperature of about 1050°C in an atmosphere of gases of halogens or 5 compounds thereof to remove the hydroxyl content for a predetermined duration of time. Thereafter the dehydrated hollow soot porous body is sintered to form a glass preform in an atmosphere of gases of halogens or compounds thereof at a temperature of about 1500°C. This step of sintering of hollow soot porous body into glass is also known as vitrification or consolidation. 10 The dehydration and sintering processes can be carried out by any method known in the art. Preferably, it can be carried out inside specially built furnaces that are equipped with one or more heating elements and gas input mechanisms. Both the dehydration and sintering processes can be carried out in same furnaces or separate furnaces. Preferably, 15 both the dehydration and sintering are carried out in same furnace. The dehydration and sintering processes comprises the steps of inserting the hollow soot porous body into a sintering furnace and subjecting it to a temperature regime under controlled chemical environment to form sintered glass preform. The chemical environment necessary for dehydration is provided with the help of gases that promote dehydration. The chemical 20 environment that is necessary for sintering is provided with gases that are inert and have high thermal conductivity. The capillary in the soot porous body is collapsed either during the sintering step or after the sintering step. After removal of the sintered glass preform (also called as 25 mother preform) from the sintering furnace and cooling down to room temperature, it is subjected to a process step of rod draw to form a plurality of core rods having predetermined diameter. Optical fiber can also be drawn from the mother preform at this stage. In this case the mother preform is transferred to the optical fiber drawing furnace after cooling it to room temperature. 30 4 Agent Docket No: BL/PAT/IN/085/001 The clad portion of the optical fiber preform is prepared by subjecting the core rod drawn to soot deposition, forming soot porous body containing core rod. This step of depositing soot over the core rod is called overcladding. Before depositing soot onto the core rod, the solid glass handles are attached to both the ends of the core rod for ease of 5 handling the optical fiber preform or precursors thereof. The soot porous body formed is then removed from the deposition machine, after cooling to room temperature it is transferred to a dehydration and sintering furnace, suspended by the glass handles, to form what is known as daughter preform. The daughter preform is transferred to optical fiber drawing furnace after cooling to room temperature and optical fiber is drawn 10 therefrom. The word precursors) is used to indicate all the intermediate products formed during the manufacture of daughter preform. The word precursor(s) therefore includes, the soot porous body, hollow soot porous body, the sintered preform (mother preform), 15 the soot porous body with core rod assembly (while preparing the daughter preform) etc. It is observed that at every stage of the optical fiber preform manufacturing process the temperature of the optical fiber preform is high, typically the temperature of the optical fiber preform and the precursors thereof is in the range of about 800°C to 20 about 1600°C or more and hence the optical fiber preform and precursors thereof need to be handled safely. It is also necessary to transfer the optical fiber preform and precursors thereof from one stage to another. Since the temperature of the optical fiber preform and the precursors thereof is in the range of about 800°C to about 1600°C or more, it is observed that it is neither possible nor safe to handle the optical fiber preform and 25 precursors thereof manually at such high temperatures. It has also been observed that as the demand for the optical fiber is increasing, it is necessary to produce bulky optical fiber preforms to increase production and reduce cost. At present the weight of the optical fiber preform and precursors thereof being 30 produced is, for example, in the order of 20 kg or more and length of a meter or more, which is definitely neither safe nor easy to handle by a human being. 5 Agent Docket No: BL/PAT/IN/085/001 It is also an observation that in the manual handling of the optical fiber preform and the precursors thereof there is always a possibility of human error leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling. 5 It is also observed that the optical fiber preform and the precursors thereof need to be handled carefully so that the surfaces of optical fiber preform and the precursors thereof are not damaged or contaminated which in turn may result in an optical fiber with low tensile strength and undesired optical parameters, for example attenuation of the 10 optical fiber, being drawn therefrom rendering it unsuitable for desired applications. The U.S. Patent application number 20070080613 [herein after referred to as US '613] discloses about a storage and transportation device for storage and transportation of optical fiber preforms and precursors thereof. The storage and transportation device for 15 optical fiber preforms is suitable for protecting the optical fiber preform and precursors thereof by isolating the same from dust particles/foreign particles and environmental gases (contamination of optical fiber preform and the precursors thereof). Though the device of US '613 for storage and transportation of optical fiber 20 preform is capable of isolating the optical fiber preform from dust particles/foreign particles and environmental gases (that is contamination of the optical fiber preform and the precursors thereof), while transferring the optical fiber preform and precursors thereof from one stage to another or transferring optical fiber preform and the precursors thereof from one stage to the device of US' 613 for storage and transportation, it is inevitable to 25 cool the optical fiber preform and precursors thereof to room temperature. From the above discussion it is clear that at every stage of optical fiber preform manufacturing the temperatures of the optical fiber preform and precursors thereof are quite high. It is necessary to cool the optical fiber preform and precursors thereof to room 30 temperature so that they can be handled safely. It has been observed by the inventor of the present invention that about 15% of the total optical fiber manufacturing process time 6 Agent Docket No: BL/PAT/IN/085/001 is wasted in cooling the optical fiber preform and precursors thereof to room temperature at various stages. Thus the constraint of cooling the optical fiber preform and precursors thereof to room temperature increases the overall process time and hence the cost of the optical fiber manufacturing process. Also the safety of the operator is at stake if the 5 optical fiber preform and precursors thereof are handled at high temperatures. Need of the Invention: Accordingly, there is a need to have a mechanism for loading and holding hot 10 optical fiber preform and precursors thereof in order to reduce the manufacturing time of the optical fiber preform and the precursors thereof and thus reduce the cost of the optical fiber manufacturing, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature and the hot optical fiber preform and precursors thereof can be loaded, held and transferred safely and easily from one stage to another 15 without manual intervention. Objects and Advantages of the Invention: The main object of the present invention is to provide a mechanism for loading 20 and holding the hot optical fiber preform and precursors thereof. Another object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and precursors thereof so as to reduce the manufacturing time and hence the cost of the optical fiber preform and precursors 25 thereof. Still another object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and precursors thereof so that the need for cooling of the precursors and the optical fiber preform is eliminated. 30 7 Agent Docket No: BL/PAT/IN/085/001 Still further object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof such that the hot optical fiber preform can be transferred safely from one stage to another without manual intervention. 5 It also an object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof, which is easy to operate. 10 Further object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof so that the surfaces of optical fiber preform and the precursors thereof are not damaged or contaminated which in turn may result in an optical fiber breaks or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom. 15 Still further object of the present invention to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof such that in the manual handling of the optical fiber preform and the precursors thereof the possibility of human error leading to damage or complete loss of the optical fiber preform and the 20 precursors thereof due to falling is eliminated. The other objects and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings which are incorporated for illustration of preferred embodiments of the present invention 25 and are not intended to limit the scope thereof. Brief Description of the Accompanying Figures: The objects and features of the present invention will become clear when read in 30 conjunction with the figures. 8 Agent Docket No: BL/PAT/IN/085/001 Figure 1 illustrates a mechanism for loading and holding the hot optical fiber preform and the precursors thereof in accordance with the preferred embodiment of the present invention. 5 Figure 2A illustrates the schematic top view of the bowl shaped gripping jaw in accordance with one embodiment of the present invention. Figure 2B illustrates the cross-sectional view of the bowl shaped gripping jaw of figure 2A 10 Figure 2C illustrates the three-dimensional view of the bowl shaped gripping jaw of figure 2 A Figure 3 illustrates the mechanism for loading and holding the hot optical fiber 15 preform and the precursors thereof holding a soot porous body (precursor) in accordance with the present invention. Figure 4 illustrates a deposition machine with a soot porous body being formed by traverse motion of the burner on the cylindrical member. 20 Figure 5 A illustrates the cross sectional view of the soot porous body deposited comprising centerline, core and part of cladding . Figure 5B illustrates the longitudinal cross-sectional view of the soot porous body 25 deposited comprising centerline, core and part of cladding. Figure 6 illustrates the sintering furnace where the soot porous body is dried and sintered. 30 Figure 7 illustrates the core rod assembly comprising core rod and handles attached to both the ends of the core rod. 9 Agent Docket No: BL/PAT/IN/085/001 Figure 8 illustrates soot porous body formed onto the core rod assembly of figure 7. 5 Brief Description of the Invention: The present invention attempts to solve the problem of loading and holding hot optical fiber preform and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof and thus reducing the manufacturing cost of 10 the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention. 15 Accordingly, the present invention relates to a novel mechanism for loading and holding hot optical fiber preform and precursors thereof, thereby, reducing the manufacturing time of the optical fiber preform and precursors thereof by eliminating the requirement of cooling of the optical fiber preform and precursors thereof to room temperature and thus reducing the overall cost of the optical fiber manufacturing, 20 meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention. In accordance with preferred embodiment of the present invention the novel mechanism for loading and holding hot optical fiber preform and precursors thereof 25 comprises a pair of arms, both held at first ends onto a support bar by means of a clamp (which may be circular or rectangular or square depending upon the shape of support bar). The clamp is of diameter or dimensions slightly greater than that of the support bar. The clamp slides along the support bar and is fixed onto the support bar with the help of screw. A support member secures each of the arm of the pair of arms from longitudinal or 30 lateral stress.. The support bar is preferably made of one of the metals including stainless steel, aluminum and have grooves so that the pair of arms with the help of clamp, can 10 Agent Docket No: BL/PAT/IN/085/001 slide along the support bar. The support bar is attached to another support, herein after referred to as support frame, in such a way that the support bar can be rotated through 360 degree in both clockwise and anticlockwise direction shown by arrow. The option of rotation of the support bar helps in holding and removing the optical fiber preform and 5 the precursors thereof from any deposition machine where the deposition is done in either vertical and/or horizontal direction. The support frame is positioned onto a flat platform with wheels. The second ends of the arm pair is provided with gripping jaws. The gripping jaws are either cup-shaped or parabola shaped or bowl shaped or a combination thereof are provided with a passage of diameter slightly greater than the diameter of 10 optical fiber preform handle so that the handles can pass through. The gripping jaws do not have any moving parts. The advantage of these immovable gripping jaws is that operations are easy and fail proof. The pair of arms is loaded onto the support bar such that the bottom of the gripping jaws faces each other. 15 In accordance with the present invention the mechanism for loading and holding the hot optical fiber preform or precursors thereof, is moved near to the optical fiber preform or the precursors thereof. One of the arms out of the pair of arms with the gripping jaws is positioned and fixed using a clamp at the lower end of the support bar while the other arm out of the arm pair, which is movable, is positioned at upper end of 20 the support bar. One conical end of the optical fiber preform or the precursors thereof with the glass handle, are positioned in the gripping jaw of the arm positioned at the lower end of the support bar. The other conical end of the optical fiber preform or precursors thereof is the capped with the second gripping jaw of the other arm by sliding the arm in vertically downward direction and then clamping the arm with the clamp. 25 When the arm is just near the conical part of the optical fiber preform, the handle of the optical fiber is slide through the passage in the gripping jaw of the upper arm. There after the arm is slide in the vertically downward direction so as to cover or cap the conical shape of the optical fiber preform. Since the gripping jaw is either cup-shaped or parabola shaped or bowl shaped or a combination thereof, once the cup shape covers the conical 30 part the optical fiber preform or precursors thereof are gripped and because of the cup- 11 Agent Docket No: BL/PAT/IN/085/001 shape or the parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances. In accordance with one embodiment all the operations described above may be 5 executed in an automated manner or manually using the mechanism for holding the hot optical fiber preform or precursors thereof of the present invention, wherein the mechanism for holding the hot optical fiber preform or precursors thereof of the present invention is provided with electromechanical devices (not shown in figure) for carrying out the operations such as rotation of the support bar , the movement of the whole 10 mechanism , the sliding movement of the arms and so on, in case the operations are executed in an automated manner. In accordance with present invention the mechanism for loading and holding the hot optical fiber preform and the precursors thereof can be used at various stages of 15 manufacturing of the optical fiber preform and precursors thereof. In one embodiment the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention can be used to remove the soot porous body after completion of soot deposition on the cylindrical member from the 20 deposition machine. In another embodiment the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention can be used to hold and transfer the soot porous body from which the sintered mother preform can be made or the 25 sintered mother preform or the soot porous body after overcladding or the sintered daughter preform and so on. The optical fiber preform and the precursors thereof can be immediately transferred in hot condition from one stage to another, meaning thereby, the need for cooling the optical fiber preforms and the precursors thereof to room temperature at any stage is eliminated. Thus, the mechanism can be used to load, hold 30 and transfer the optical fiber preform and the precursor thereof even when they are hot, meaning thereby, the process time can be shorten or reduced. 12 Agent Docket No: BL/PAT/IN/085/001 Detailed Description and Preferred Embodiments of the Invention: Reference will now be made in detail to the preferred embodiments of the present 5 invention, examples of which are illustrated in the accompanying drawings, which are not intended to limit scope of the present invention. Whenever possible, the same reference numerals will be used throughout the description to refer to the same or like parts of the invention. 10 The present invention aims at solving the problem of loading and holding hot optical fiber preform and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, 15 the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention. Now referring to Figure 1, in accordance with preferred embodiment of the present invention the novel mechanism 101 for loading and holding hot optical fiber 20 preform and precursors thereof comprises a pair of arms 103, both held at first ends 103a onto a support bar 105 by means of clamp 106 (which may be circular or rectangular or square depending upon the shape of support bar 105). The clamp 106 is of diameter or dimensions slightly greater than that of the support bar 105. The clamp 106 slides along the support bar 105 and fixed onto the support bar 105 with the help of screw 107. A 25 support member 104 secure each of the arm of the pair of arms 103 from longitudinal or lateral stress. The support bar 105 is made of one of the metals out of the group of metals including stainless steel, aluminum etc and have grooves 113 so that the pair of arms 103 with the help of clamp 106 can slide along the support bar 105. The support bar 105 is attached to another support, referred to as support frame 109 in such a way that the 30 support bar 105 can be rotated through 360 degree in both clockwise and anticlockwise direction shown by arrow 108. The option of rotation of the support bar 105 helps in 13 Agent Docket No: BL/PAT/IN/085/001 holding and removing the optical fiber preform and the precursors thereof from the any deposition machine where the deposition is done in either vertical and/or horizontal direction. The support frame 109 is positioned onto a flat platform 111 with wheels 112. The second ends 103b of the arm pair 103 are provided with gripping jaws 102. The 5 gripping jaws 102 are either cup-shaped or parabola shaped or bowl shaped or a combination thereof and are provided with a passage 204 (figure 2A and 2C) of diameter slightly greater than the diameter of optical fiber preform handle so that the handles 405 or 702 or 802 (figure 4, figure 7 and figure 8) can pass through. The gripping jaws 102 do not have any moving parts. The advantage of these immovable gripping jaws 102 is that 10 operations are easy and fail proof. The pair of arms 103 is loaded onto the support bar 105 such that the bottom 102a of the gripping jaws 103 faces each other (Figure 1 and Figure 2B). Figure 2 A illustrates the schematic top view of the bowl shaped gripping jaw 102 15 in accordance with one embodiment of the present invention. The gripping jaw 102 comprises of a bowl shaped body 201, with the base 203 of the bowl 201 flat (figure 2B and figure 2C), the base 203 and the bowl 201 are cut so as to form the passage 204. The diameter of passage 204 is slightly greater than that of the handle 405/702/802 of the optical fiber preform and precursors thereof so that the handle 405/702/802 can be slide 20 in. The gripping jaw 102 can be attached to the arms 103 by screwing or welding. Figure 2B illustrates the cross-sectional view of the gripping jaw 103 in accordance with the present invention. The gripping jaw 102 has two sides namely, the bottom 102a and the top 102b (figure 2B). Figure 2C illustrates a three-dimensional view of the gripping jaw 102 in accordance with one embodiment of the present invention. 25 It has been observed that the gripping jaws 102 or 302 of the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention are without any moving parts and has the advantage of being easy to operate, hold the optical fiber preform and without fear of slipping of the optical fiber preform 30 and precursors thereof, during the holding and transfer from one stage to another. 14 Agent Docket No: BL/PAT/IN/085/001 In accordance with the present invention the gripping jaw 102 or 302 can be made up of any material that is non-corrosive and capable of bearing high temperature and weight of the optical fiber preform and precursors thereof. 5 In accordance with one embodiment of the present invention the gripping jaw 102 or 302 can be made up of one of the metals out of the group of metals including stainless steel, aluminum etc coated with teflon. In one embodiment the gripping jaw 102 or 302 can be cup-shaped or parabola 10 shaped according to the need. Now referring to figure 3 and figure 4 the working of the mechanism 301 for loading and holding the hot optical fiber preform and precursors thereof is explained. In accordance with the present invention the mechanism for loading and holding the optical 15 fiber preform or precursors thereof, is moved near to the optical fiber preform or the precursors thereof. One of the arms out of the pair of arms 303 with the gripping jaws 302 is positioned and fixed using a clamp 306, at the lower end of the support bar 305 while the other arm out of the arm pair 303, which is movable, is positioned at upper end of the support bar 305. One conical end 401b of the optical fiber preform 401 or the 20 precursors thereof with the glass handle 405, are positioned in the gripping jaw 302 of the arm positioned at the lower end of the support bar 305. The other conical end 401a of the optical fiber preform or precursors thereof is the capped with the second gripping jaw 302 of the other arm 303 by sliding the arm in vertically downward direction and then clamping the arm with screw 307 of the clamp 306. When the arm is just near the conical 25 part 401 a of the optical fiber preform 401, the handle 405 of the optical fiber preform 401 is slide through the passage 204 in the gripping jaw 302 of the upper arm. There after the arm is slide in the vertically downward direction so as to cover or cap the conical shape 401a of the optical fiber preform 401 (as shown in figure 3) completely. Since the gripping jaw 302 is either cup-shaped or parabola shaped or bowl shaped or a 30 combination thereof, once the cup shape covers the conical part 401a or 401b the optical fiber preform or precursors 401 thereof are gripped and because of the cup-shape or the 15 Agent Docket No: BL/PAT/IN/085/001 parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances. In accordance with one embodiment all the operations described above may be 5 executed in an automated manner or manually using the mechanism for loading and holding the hot optical fiber preform or precursors thereof of the present invention, wherein the mechanism for loading and holding the hot optical fiber preform or precursors thereof of the present invention is provided with electromechanical devices (not shown in figure) for carrying out the operations such as rotation of the support bar 10 305, the movement of the whole mechanism 301, the sliding movement of the arms 303 and so on, in case if the operations are executed in an automated manner. Such automation that is, carrying out of operations such as rotation of the support bar 305, the movement of the whole mechanism 301 the sliding movements of the arms 303 are available commercially. 15 In accordance with present invention the mechanism for loading and holding the hot optical fiber preform and the precursors thereof can be used at various stages of manufacturing of the optical fiber preform and precursors thereof. 20 In one embodiment the mechanism of the present invention can be used to remove the soot porous body after completion of soot deposition on the cylindrical member the soot preform is removed from the deposition machine. In another embodiment the mechanism of the present invention can be used to 25 load, hold and transfer the soot porous body from which the sintered mother preform can be made or the sintered mother preform or the soot porous body after overcladding or the sintered daughter preform and so on. The optical fiber preform and the precursors thereof can be immediately transferred in hot condition from one stage to another, meaning thereby, the need for cooling the optical fiber preforms and the precursors thereof to 30 room temperature in any stage is eliminated. Thus, the mechanism can be used to hold 16 Agent Docket No: BL/PAT/IN/085/001 and transfer the optical fiber preform and the precursor thereof even when they are hot, meaning thereby, the process time can be shorten or reduced. Figure 4 illustrates an exemplary soot deposition machine 407, wherein, the core 5 portion of the optical fiber preform and part of the cladding is deposited by Atmospheric Chemical Vapor Deposition (ACVD) method, wherein the soot is deposited on the cylindrical member 403 (also referred as target rod or mandrel) with a hollow glass handle 405 intact, which is used for ease of handling the soot porous body 402 so formed. In this method, the deposition of soot 409 is accomplished by traverse motion of the 10 cylindrical member 403 over the burner(s) 408 or vice versa, while rotating the cylindrical member 403 (rotation indicated by the arrow 406). The burner(s) 408 are supplied with silicon containing materials (for example, silicon tetrachloride), gases supporting oxidation (for example oxygen) and heat producing gases (for example hydrogen, methane etc) (not shown in the figure). The oxidation of silicon containing 15 materials takes place-forming oxides of silicon, which is generally referred to as soot 409. The initial soot deposition comprises dopant chemicals to increase refractive index of the core and dopant chemicals are terminated after desired core diameter is obtained. The deposition process continues until the required dimension of the soot porous body 402 is attained for meeting desired core diameter in the optical fiber preform and the 20 desired core-clad diameter ratio in the fiber. After completion of soot deposition, the soot porous body can be removed from the soot deposition machine 407 without need for cooling down to room temperature, held and transferred to storage cabin by using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention. The cylindrical member 403 is removed from the soot 25 porous body 402, after cooling the soot porous body 402 to room temperature, to form hollow soot porous body 501 defining a capillary 502 at the center [herein after referred to as hollow soot porous body]. Figure 5A and Figure 5B illustrates the cross-sectional and longitudinal view of the hollow soot porous body 501 comprising the capillary 502, the core part 503 and the part of cladding 504. 30 17 Agent Docket No: BL/PAT/IN/085/001 The hollow soot porous body 501 so formed by the ACVD method contains large amount of hydroxyl group or water as generally referred to. In order to remove the hydroxyl content of the hollow soot porous body 501, it is treated with gases, which chemically reacts with the hydroxyl group. Halogens or compounds of halogen are 5 generally used for such purpose. This step of removing the hydroxyl content from the hollow soot porous body is known as dehydration or drying. In this step of dehydration or drying at first a glass plug is inserted into the end remote from the handle of the hollow soot porous body. The cooled hollow soot porous body 501 is moved into a furnace 601, suspended by the hollow handle 405 in the furnace 601, wherein this hollow soot porous 10 body 501 is heated at a temperature of about 1050°C in an atmosphere of gases of halogens or compounds thereof to remove the hydroxyl content for a predetermined duration of time. Thereafter the dehydrated hollow soot porous body 501 is sintered to form a glass preform in an atmosphere of gases of halogens or compounds thereof at a temperature of about 1500°C. This step of sintering of hollow soot porous body in to 15 glass is also known as vitrification or consolidation. Figure 6 illustrates the dehydration and sintering furnace 601 for dehydration and sintering of the hollow soot porous body 501. A glass plug 608 is inserted into the end remote from the handle 405 of the hollow soot porous body 501. The cooled hollow soot 20 porous body 501 is inserted into dehydration and sintering furnace 601, suspended by the hollow handle 405 in the sintering furnace, wherein this hollow soot porous body 501 is first dehydrated at a temperature of about 1050°C and then sintered (also known as vitrification or consolidation) in a chlorine and helium atmosphere to form optical fiber preform at about 1500°C. The dehydration and sintering is preferably carried out in the 25 same furnace to avoid contamination of dehydrated hollow soot porous body 501. The dehydration and sintering furnace 601 is specially built for the purpose equipped with one or more heating elements 604 and gas inlets 602 and reaction product-scrubbing outlet 603. The hollow soot porous body 501 is suspended in the dehydration and sintering furnace 601 by the suspension device 607. The dehydration and sintering processes 30 comprise inserting the hollow cylindrical soot porous body 501 into a sintering furnace 601 and subjecting it to a temperature regime under controlled chemical environment to 18 Agent Docket No: BL/PAT/IN/085/001 form sintered glass preform sequentially. The chemical environment necessary for dehydration is provided with the help of gases that promote dehydration. The chemical environment that is necessary for sintering is provided with gases that are inert and have high thermal conductivity. The gases are provided through the inlet 602 and scrubbed 5 through the upper outlet 603. The sintering furnace is covered at the top with a plate 606 that avoids the ingress of atmospheric air into the furnace and leakage of gases inside the furnace into the environment. The capillary 502 in the hollow soot porous body is collapsed either during the 10 sintering step or after the sintering step. The collapse of the capillary 502 takes place under vacuum. A tube 609 is attached to the hollow handle 405 and is connected to vacuum pump. There after the sintered glass preform (also called as mother preform), after removal from the sintering furnace 601 is held and transferred to the rod draw furnace by using the mechanism of the present invention for holding the optical fiber 15 preform and precursors thereof without need for cooling down to room temperature, (Figure 2), wherein it is subjected to a process step of rod draw to form a plurality of core rods having predetermined diameter. Optical fiber can also be drawn from the mother preform at this stage. In this case the mother preform is held and transferred to the optical fiber drawing furnace, by using the mechanism for loading and holding the hot optical 20 fiber preform and the precursors thereof of the present invention to the optical fiber, in hot condition without need for cooling down to room temperature. Figure 7 depicts the core rod assembly 701 prepared by heat welding glass handles 702 to both the ends of core rod 703 obtained by drawing mother preform. The 25 core rod assembly is subjected to a step of over cladding thereafter. The core rod assembly 701 after preparation is hot and can be held and transferred to the deposition machine, similar to the deposition machine 407, for overcladding the core rod assembly, by using the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention. 30 19 Agent Docket No: BL/PAT/IN/085/001 The core rod assembly 701 is placed inside the deposition machine, wherein soot is deposited onto the core rod assembly 701 using burners similar to that used for preparation of mother perform to form soot porous body 801 (Figure 8). This step of depositing soot over the core rod is called overcladding. The soot porous body 804 5 formed is then removed from the deposition machine, without need for cooling down to room temperature, it is held and transferred, using the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention, to a dehydration and sintering furnace similar to that for dehydration and sintering hollow soot porous body. The temperature of the dehydration is about 1200°C and that of 10 sintering is about 1550°C. The soot porous body suspended by the glass handles 802, to form what is known as daughter preform. Again without need for cooling down to room temperature, it is held and transferred to the optical fiber draw furnace using the mechanism for loading and 15 holding the hot optical fiber preform and the precursors thereof of the present invention, to draw optical fiber therefrom. In accordance with the present invention the mechanism for loading and holding the hot optical fiber preform and the precursors thereof can be used to handle the optical 20 fiber preform and precursors thereof, safely and can also be transferred from one stage to another or from one stage to the storage and transportation device of US' 613, though at every stage of the optical fiber preform manufacturing process the temperature of the optical fiber preform and the precursors thereof is high, typically the temperature is in the range of about 800°C to about 1600°C or more. 25 The various parts of the mechanism for loading and holding hot optical fiber preform and precursors thereof of the present invention are made of metals out of the group of metals including stainless steel, aluminum etc preferably coated with teflon. 30 It is observed that not only hot but it is also possible to load, hold and transfer bulky optical fiber preforms and precursors thereof to increase production and reduce 20 Agent Docket No: BL/PAT/IN/085/001 manufacturing cost. Using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the optical fiber preform and precursors thereof, for example, in the order of 20 kg or more and length of a meter or more, can be safely, easily and without any human intervention transferred from one 5 stage to another. In accordance with the present invention using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the limitation of the device of US '613 for storage and transportation of optical fiber 10 preform and precursors thereof, of necessity to cool the optical fiber preform and precursors thereof is eliminated as the hot optical fiber preform and precursors thereof can be held and transferred from one stage to another using combination of the mechanism of the present invention and the device of US '613. 15 In accordance with the present invention the manual handling of the optical fiber preform and the precursors thereof and the possibility of human error leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling is eliminated by using the novel mechanism of the for loading and holding the hot optical fiber preform and precursors thereof. 20 In accordance with the present invention the mechanism for loading and holding hot optical fiber preform and precursors thereof eliminates the problem of damage or contamination of the optical fiber preform or precursors thereof, which may occur during handling or transferring of the same and which in turn may result in an optical fiber with 25 low tensile strength or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom that renders the optical fiber obtained therefrom unsuitable for desired applications . In accordance with the present invention the necessity to cool the optical fiber 30 preform and precursors thereof to room temperature, is eliminated completely, so that they can be handled safely. 21 Agent Docket No: BL/PAT/IN/085/001 One advantage of the present invention is that about 15% of the total optical fiber manufacturing process time is saved, by making it possible to hold and transfer the optical fiber preform and precursors thereof in hot conditions at various stages using the 5 mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention. Another advantage of the present invention is that the constraint of cooling the optical fiber preform and precursors thereof to room temperature, is eliminated, meaning 10 thereby, the overall process time and hence the cost of the optical fiber manufacturing process is reduced. It is also an advantage of using the mechanism for loading and holding hot optical fiber preform or precursors thereof of the present invention the possibility of human error 15 leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling is eliminated. Further it is observed that using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention is not at all 20 complicated. Further it is observed that by using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the problem of damages or contamination to the surfaces of optical fiber preform and the precursors 25 thereof which in turn may result in an optical fiber breaks or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom is eliminated. 22 Agent Docket No: BL/PAT/IN/085/001 What is claimed is: 1. A mechanism (101) for loading and holding hot optical fiber preform and precursors thereof, the mechanism comprise: 5 a. a support bar (105) to support a pair of arms (103) at one end (103a); b. a pair of arms (103), to hold optical fiber perform and precursors thereof, each arm having a clamp (106) arrangement at one end, each clamp (106) having a screw (107), each of said clamps (106) being shaped in such a way so as to slide along said support bar (105) and to get fixed onto said 10 support bar (105) when said screw (107) of the said clamp (106) is tightened; c. a support member (104) to secure each of the arm of said pair of arms (103) from longitudinal or lateral stress; d. a support frame (109), said support bar (105) being connected to said 15 support frame (109) in a manner so as to allow 360 degree rotation of said support bar (105) in both clockwise and anticlockwise direction, so as to allow loading, holding and removing of optical fiber preform and precursors thereof in vertical, horizontal or any angular position; e. a flat platform (111) with wheels (112), to position the support frame 20 (109) to enable easy movement of said mechanism (101); and f. a gripping jaw (102) at the second end (103b) of each of said pair of arms (103), where said support bar (105) has grooves (113) so that the pair of arms with the help of 25 clamp (106) can slide along the support bar (105) and where the pair of arms (103) are loaded onto the support bar such that the gripping jaws face (102a) each other. 2. Mechanism (101) as in claim 1, where the clamps (106) are circular in shape; 30 3. Mechanism (101) as in claim 1, where the clamps (106) are rectangular in shape; 23 Agent Docket No: BL/PAT/N/085/001 4. Mechanism (101) as in claim 1, where the clamps (106) are square in shape; 5 10 5. Mechanism (101) as in claim 1, the mechanism (101) further comprising electromechanical means to enable control of the movements of said mechanism. 6. Mechanism (101) as in claim 1, where the support bar (105) is made of one of the metals out of the group of metals including stainless steel, aluminum or iron. 7. Mechanism (101) as in claim 1, where the gripping jaws (102) are cup-shaped 8. Mechanism (101) as in claim 1, where the gripping jaws (102) are parabola shaped 9. Mechanism (101) as in claim 1, where the gripping jaws (102) are bowl shaped 15 10. Mechanism (101) as in claim 1, where the gripping jaws (102) are provided with a passage (204) of diameter slightly greater than the diameter of optical fiber preform handle (405/702/802) so that the handles (405/702/802) can pass through. 11. Method for loading and holding the hot optical fiber preform or precursors thereof, 20 using a mechanism (101) as claimed in claim 1, the method comprising the steps of: a. having one of the arms out of the pair of arms (3 03) with the gripping jaws (302) positioned and fixed using a clamp (306) at the lower end of the support bar (305); b. positioning the second arm out of the arm pair (303) using the sliding 25 clamp (306) at the upper end of the support bar (305); c. positioning in the gripping jaw (302) of the arm positioned at the lower end of the support bar (305) one conical end (401b) of the optical fiber preform or the precursors thereof with the glass handle; d. capping the other conical end (401a) of the optical fiber preform or 30 precursors (401) thereof with the second gripping jaw (302) of the other arm by sliding the arm in vertically downward direction; 24 Agent Docket No: BL/PAT/IN/085/001 e. sliding the handle (405) of the optical fiber preform or precursors thereof (401) through the passage (204) in the gripping jaw (302) of the upper arm so as to cover the conical shape (401a) of the optical fiber preform; and f. clamping the arm with the clamp (306); 5 where the gripping jaw (302) is either cup-shaped or parabola shaped or bowl shaped or a combination thereof, once the cup shape covers the conical part the optical fiber preform or precursors thereof are gripped and because of the cup-shape or the parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances and where said mechanism for loading and holding 10 the hot optical fiber preform and the precursors thereof can be used at various stages of manufacturing of the optical fiber preform and precursors thereof. 12. Method as in claim 11, where the method can be used to remove the soot porous body after completion of soot deposition on the mandrel the soot preform is removed from 15 the deposition machine. 13. Method as in claim 11, where the method can be used to hold and transfer the soot porous body from which the sintered mother preform can be made or the sintered mother preform or the soot porous body after overcladding or the sintered daughter 20 preform and so on. 14. Method as in claim 11, where the steps of the method are performed in an automated manner. 25 Agent Docket No: BL/PAT/IN/085/001 Abstract A novel mechanism for holding hot optical fiber preform and precursors thereof is disclosed. The present invention solves the problem of holding hot optical fiber preform 5 and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from 10 one stage to another without manual intervention. 26 Agent Docket No: BL/PAT/IN/085/001

Full Text

FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005
COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13)
TITLE OF THE INVENTION
"A NOVEL MECHANISM FOR LOADING AND HOLDING HOT OPTICAL FIBER PREFORM AND PRECURSORS THEREOF."
APPLICANTS:
Name : Sterlite Optical Technologies Ltd
Nationality : Indian (A Company Registered under Indian Companies Act)
Address : El, E2, E3, MIDC, Waluj, Aurangabad, INDIA - 431136,
The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-
1 Agent Docket No: BL/PAT/IN/085/001

Field of the Invention:
The present invention relates to a novel mechanism for loading and holding hot
optical fiber preform and precursors thereof. Particularly, the present invention relates to
5 a novel mechanism for loading and holding hot optical fiber preform and precursors thereof, capable of loading and holding bulky optical fiber preform and precursors
thereof reducing overall manufacturing time and making the transportation of optical
fiber preform and precursors thereof simple and safe.
10 Background of Invention:
The role of Optical fibers has become significant in the field of communications.
There has been a momentous increase in usage of optical fibers. It is expected that the use
of optical fibers in local loop telephone and cable TV service will increase in order to
15 deliver greater amount of information in the form of data, audio, and video signals to
residential and commercial users.
Optical fiber comprise a core and a cladding surrounding the core. The refractive index of core is higher as compared with the refractive index of the cladding in order to
20 achieve light transmission inside the optical fiber, by the phenomena known as total internal reflection. Generally, either the refractive index of the core is substantially uniform across its diameter (also called step index optical fiber) or the refractive index of the core has a maximum at the center and decrease in parabolic fashion near the periphery (also called graded index optical fiber). Any other geometric shape and profile
25 of the refractive index of the core is possible catering to a particular need.
It is desirable that the manufacturing process of the optical fiber preform and
precursors thereof to be economical in order to support the increasing demand of optical
fiber and that too at low cost, meaning thereby, it is necessary to improve the production
30 efficiency of the optical fiber manufacturing process. Reducing the manufacturing time
can enhance the production efficiency of the optical fiber preform and precursors
2 Agent Docket No: BL/PAT/IN/085/001

manufacturing process, which in turn means that it is necessary to reduce the optical fiber preform and precursors manufacturing process time as much as possible.
In batch type manufacturing, the optical fiber is obtained by drawing optical fiber
5 preform. The optical fiber preform is an enlarged image of optical fiber, which like the optical fiber comprises a central core portion and an outer cladding. The core portion comprises the core and a part of cladding of the fiber preform. The core portion of the optical fiber preform can be prepared by any known methods, for example, by Atmospheric Chemical Vapor Deposition (ACVD) method, wherein the soot is deposited
10 during the deposition process step on the cylindrical member (also referred as target rod or mandrel) with a hollow glass handle intact, used for ease of handling the soot porous body so formed. In this method, the soot deposition is accomplished by traverse motion of the cylindrical member over the burners or vice versa while rotating the cylindrical member. The burners are supplied with silicon containing materials (for example silicon
15 tetrachloride), gases supporting oxidation (for example oxygen) and heat producing gases (for example hydrogen, methane etc). The oxidation of silicon containing materials takes place resulting in the formation of oxides of silicon, which is generally referred to as soot. The initial soot deposition comprises dopant chemicals (for example germanium tetrachloride) to increase refractive index of the core and dopant chemicals are terminated
20 after desired core diameter is obtained. The deposition process continues until the required dimension of the soot porous body is attained for meeting desired core diameter in the optical fiber preform and the desired core-clad diameter ratio in the fiber. After completion of soot deposition and on cooling the soot porous body to room temperature, the cylindrical member is removed from the soot porous body, to form hollow cylindrical
25 soot porous body defining a capillary at the center [herein after referred to as hollow soot porous body]. The hollow soot porous body so formed by the ACVD method contains large amount of hydroxyl group or water as generally referred to. In order to remove the hydroxyl content of the hollow soot porous body, it is treated with gases, which chemically reacts with the hydroxyl group. Halogens or compounds of halogen are
30 generally used for such purpose. This step of removing the hydroxyl content from the hollow soot porous body is known as dehydration or drying. In this step of dehydration or
3 Agent Docket No: BL/PAT/IN/085/001

drying at first a glass plug is inserted into the end remote from the handle of the hollow soot porous body. The cooled hollow soot porous body is moved into a furnace, suspended by the hollow handle in the furnace, wherein this hollow soot porous body is heated at a temperature of about 1050°C in an atmosphere of gases of halogens or
5 compounds thereof to remove the hydroxyl content for a predetermined duration of time. Thereafter the dehydrated hollow soot porous body is sintered to form a glass preform in an atmosphere of gases of halogens or compounds thereof at a temperature of about 1500°C. This step of sintering of hollow soot porous body into glass is also known as vitrification or consolidation.
10
The dehydration and sintering processes can be carried out by any method known in the art. Preferably, it can be carried out inside specially built furnaces that are equipped with one or more heating elements and gas input mechanisms. Both the dehydration and sintering processes can be carried out in same furnaces or separate furnaces. Preferably,
15 both the dehydration and sintering are carried out in same furnace. The dehydration and sintering processes comprises the steps of inserting the hollow soot porous body into a sintering furnace and subjecting it to a temperature regime under controlled chemical environment to form sintered glass preform. The chemical environment necessary for dehydration is provided with the help of gases that promote dehydration. The chemical
20 environment that is necessary for sintering is provided with gases that are inert and have high thermal conductivity.
The capillary in the soot porous body is collapsed either during the sintering step or after the sintering step. After removal of the sintered glass preform (also called as
25 mother preform) from the sintering furnace and cooling down to room temperature, it is subjected to a process step of rod draw to form a plurality of core rods having predetermined diameter. Optical fiber can also be drawn from the mother preform at this stage. In this case the mother preform is transferred to the optical fiber drawing furnace after cooling it to room temperature.
30
4 Agent Docket No: BL/PAT/IN/085/001

The clad portion of the optical fiber preform is prepared by subjecting the core rod drawn to soot deposition, forming soot porous body containing core rod. This step of depositing soot over the core rod is called overcladding. Before depositing soot onto the core rod, the solid glass handles are attached to both the ends of the core rod for ease of
5 handling the optical fiber preform or precursors thereof. The soot porous body formed is then removed from the deposition machine, after cooling to room temperature it is transferred to a dehydration and sintering furnace, suspended by the glass handles, to form what is known as daughter preform. The daughter preform is transferred to optical fiber drawing furnace after cooling to room temperature and optical fiber is drawn
10 therefrom.
The word precursors) is used to indicate all the intermediate products formed during the manufacture of daughter preform. The word precursor(s) therefore includes, the soot porous body, hollow soot porous body, the sintered preform (mother preform),
15 the soot porous body with core rod assembly (while preparing the daughter preform) etc.
It is observed that at every stage of the optical fiber preform manufacturing process the temperature of the optical fiber preform is high, typically the temperature of the optical fiber preform and the precursors thereof is in the range of about 800°C to
20 about 1600°C or more and hence the optical fiber preform and precursors thereof need to be handled safely. It is also necessary to transfer the optical fiber preform and precursors thereof from one stage to another. Since the temperature of the optical fiber preform and the precursors thereof is in the range of about 800°C to about 1600°C or more, it is observed that it is neither possible nor safe to handle the optical fiber preform and
25 precursors thereof manually at such high temperatures.
It has also been observed that as the demand for the optical fiber is increasing, it
is necessary to produce bulky optical fiber preforms to increase production and reduce
cost. At present the weight of the optical fiber preform and precursors thereof being
30 produced is, for example, in the order of 20 kg or more and length of a meter or more,
which is definitely neither safe nor easy to handle by a human being.
5 Agent Docket No: BL/PAT/IN/085/001

It is also an observation that in the manual handling of the optical fiber preform and the precursors thereof there is always a possibility of human error leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling.
5
It is also observed that the optical fiber preform and the precursors thereof need
to be handled carefully so that the surfaces of optical fiber preform and the precursors
thereof are not damaged or contaminated which in turn may result in an optical fiber with
low tensile strength and undesired optical parameters, for example attenuation of the
10 optical fiber, being drawn therefrom rendering it unsuitable for desired applications.
The U.S. Patent application number 20070080613 [herein after referred to as US '613] discloses about a storage and transportation device for storage and transportation of optical fiber preforms and precursors thereof. The storage and transportation device for
15 optical fiber preforms is suitable for protecting the optical fiber preform and precursors thereof by isolating the same from dust particles/foreign particles and environmental gases (contamination of optical fiber preform and the precursors thereof).
Though the device of US '613 for storage and transportation of optical fiber
20 preform is capable of isolating the optical fiber preform from dust particles/foreign particles and environmental gases (that is contamination of the optical fiber preform and the precursors thereof), while transferring the optical fiber preform and precursors thereof from one stage to another or transferring optical fiber preform and the precursors thereof from one stage to the device of US' 613 for storage and transportation, it is inevitable to
25 cool the optical fiber preform and precursors thereof to room temperature.
From the above discussion it is clear that at every stage of optical fiber preform
manufacturing the temperatures of the optical fiber preform and precursors thereof are
quite high. It is necessary to cool the optical fiber preform and precursors thereof to room
30 temperature so that they can be handled safely. It has been observed by the inventor of
the present invention that about 15% of the total optical fiber manufacturing process time
6 Agent Docket No: BL/PAT/IN/085/001

is wasted in cooling the optical fiber preform and precursors thereof to room temperature at various stages. Thus the constraint of cooling the optical fiber preform and precursors thereof to room temperature increases the overall process time and hence the cost of the optical fiber manufacturing process. Also the safety of the operator is at stake if the
5 optical fiber preform and precursors thereof are handled at high temperatures.
Need of the Invention:
Accordingly, there is a need to have a mechanism for loading and holding hot 10 optical fiber preform and precursors thereof in order to reduce the manufacturing time of the optical fiber preform and the precursors thereof and thus reduce the cost of the optical fiber manufacturing, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature and the hot optical fiber preform and precursors thereof can be loaded, held and transferred safely and easily from one stage to another
15 without manual intervention.
Objects and Advantages of the Invention:
The main object of the present invention is to provide a mechanism for loading
20 and holding the hot optical fiber preform and precursors thereof.
Another object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and precursors thereof so as to reduce the manufacturing time and hence the cost of the optical fiber preform and precursors
25 thereof.
Still another object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and precursors thereof so that the need for cooling of the precursors and the optical fiber preform is eliminated.
30
7 Agent Docket No: BL/PAT/IN/085/001

Still further object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof such that the hot optical fiber preform can be transferred safely from one stage to another without manual intervention.
5
It also an object of the present invention is to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof, which is easy to operate.
10 Further object of the present invention is to provide a mechanism for loading and
holding the hot optical fiber preform and the precursors thereof so that the surfaces of optical fiber preform and the precursors thereof are not damaged or contaminated which in turn may result in an optical fiber breaks or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom.
15
Still further object of the present invention to provide a mechanism for loading and holding the hot optical fiber preform and the precursors thereof such that in the manual handling of the optical fiber preform and the precursors thereof the possibility of human error leading to damage or complete loss of the optical fiber preform and the
20 precursors thereof due to falling is eliminated.

The other objects and advantages of the present invention will be apparent from
the following description when read in conjunction with the accompanying drawings
which are incorporated for illustration of preferred embodiments of the present invention
25 and are not intended to limit the scope thereof.
Brief Description of the Accompanying Figures:
The objects and features of the present invention will become clear when read in
30 conjunction with the figures.
8 Agent Docket No: BL/PAT/IN/085/001

Figure 1 illustrates a mechanism for loading and holding the hot optical fiber preform and the precursors thereof in accordance with the preferred embodiment of the present invention.
5 Figure 2A illustrates the schematic top view of the bowl shaped gripping jaw in
accordance with one embodiment of the present invention.
Figure 2B illustrates the cross-sectional view of the bowl shaped gripping jaw of figure 2A
10
Figure 2C illustrates the three-dimensional view of the bowl shaped gripping jaw of figure 2 A
Figure 3 illustrates the mechanism for loading and holding the hot optical fiber
15 preform and the precursors thereof holding a soot porous body (precursor) in accordance with the present invention.
Figure 4 illustrates a deposition machine with a soot porous body being formed by traverse motion of the burner on the cylindrical member.
20
Figure 5 A illustrates the cross sectional view of the soot porous body deposited comprising centerline, core and part of cladding .
Figure 5B illustrates the longitudinal cross-sectional view of the soot porous body 25 deposited comprising centerline, core and part of cladding.
Figure 6 illustrates the sintering furnace where the soot porous body is dried and sintered.
30 Figure 7 illustrates the core rod assembly comprising core rod and handles
attached to both the ends of the core rod.
9 Agent Docket No: BL/PAT/IN/085/001

Figure 8 illustrates soot porous body formed onto the core rod assembly of figure 7.
5 Brief Description of the Invention:
The present invention attempts to solve the problem of loading and holding hot
optical fiber preform and precursors thereof and reducing the manufacturing time of the
optical fiber preform and precursors thereof and thus reducing the manufacturing cost of
10 the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention.
15 Accordingly, the present invention relates to a novel mechanism for loading and
holding hot optical fiber preform and precursors thereof, thereby, reducing the manufacturing time of the optical fiber preform and precursors thereof by eliminating the requirement of cooling of the optical fiber preform and precursors thereof to room temperature and thus reducing the overall cost of the optical fiber manufacturing,
20 meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention.
In accordance with preferred embodiment of the present invention the novel mechanism for loading and holding hot optical fiber preform and precursors thereof
25 comprises a pair of arms, both held at first ends onto a support bar by means of a clamp (which may be circular or rectangular or square depending upon the shape of support bar). The clamp is of diameter or dimensions slightly greater than that of the support bar. The clamp slides along the support bar and is fixed onto the support bar with the help of screw. A support member secures each of the arm of the pair of arms from longitudinal or
30 lateral stress.. The support bar is preferably made of one of the metals including stainless
steel, aluminum and have grooves so that the pair of arms with the help of clamp, can
10 Agent Docket No: BL/PAT/IN/085/001

slide along the support bar. The support bar is attached to another support, herein after referred to as support frame, in such a way that the support bar can be rotated through 360 degree in both clockwise and anticlockwise direction shown by arrow. The option of rotation of the support bar helps in holding and removing the optical fiber preform and
5 the precursors thereof from any deposition machine where the deposition is done in either vertical and/or horizontal direction. The support frame is positioned onto a flat platform with wheels. The second ends of the arm pair is provided with gripping jaws. The gripping jaws are either cup-shaped or parabola shaped or bowl shaped or a combination thereof are provided with a passage of diameter slightly greater than the diameter of
10 optical fiber preform handle so that the handles can pass through. The gripping jaws do not have any moving parts. The advantage of these immovable gripping jaws is that operations are easy and fail proof. The pair of arms is loaded onto the support bar such that the bottom of the gripping jaws faces each other.
15 In accordance with the present invention the mechanism for loading and holding
the hot optical fiber preform or precursors thereof, is moved near to the optical fiber preform or the precursors thereof. One of the arms out of the pair of arms with the gripping jaws is positioned and fixed using a clamp at the lower end of the support bar while the other arm out of the arm pair, which is movable, is positioned at upper end of
20 the support bar. One conical end of the optical fiber preform or the precursors thereof with the glass handle, are positioned in the gripping jaw of the arm positioned at the lower end of the support bar. The other conical end of the optical fiber preform or precursors thereof is the capped with the second gripping jaw of the other arm by sliding the arm in vertically downward direction and then clamping the arm with the clamp.
25 When the arm is just near the conical part of the optical fiber preform, the handle of the optical fiber is slide through the passage in the gripping jaw of the upper arm. There after the arm is slide in the vertically downward direction so as to cover or cap the conical shape of the optical fiber preform. Since the gripping jaw is either cup-shaped or parabola shaped or bowl shaped or a combination thereof, once the cup shape covers the conical
30 part the optical fiber preform or precursors thereof are gripped and because of the cup-
11 Agent Docket No: BL/PAT/IN/085/001

shape or the parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances.
In accordance with one embodiment all the operations described above may be
5 executed in an automated manner or manually using the mechanism for holding the hot optical fiber preform or precursors thereof of the present invention, wherein the mechanism for holding the hot optical fiber preform or precursors thereof of the present invention is provided with electromechanical devices (not shown in figure) for carrying out the operations such as rotation of the support bar , the movement of the whole
10 mechanism , the sliding movement of the arms and so on, in case the operations are executed in an automated manner.

In accordance with present invention the mechanism for loading and holding the
hot optical fiber preform and the precursors thereof can be used at various stages of
15 manufacturing of the optical fiber preform and precursors thereof.
In one embodiment the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention can be used to remove the soot porous body after completion of soot deposition on the cylindrical member from the
20 deposition machine.
In another embodiment the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention can be used to hold and transfer the soot porous body from which the sintered mother preform can be made or the
25 sintered mother preform or the soot porous body after overcladding or the sintered daughter preform and so on. The optical fiber preform and the precursors thereof can be immediately transferred in hot condition from one stage to another, meaning thereby, the need for cooling the optical fiber preforms and the precursors thereof to room temperature at any stage is eliminated. Thus, the mechanism can be used to load, hold
30 and transfer the optical fiber preform and the precursor thereof even when they are hot, meaning thereby, the process time can be shorten or reduced.
12 Agent Docket No: BL/PAT/IN/085/001

Detailed Description and Preferred Embodiments of the Invention:
Reference will now be made in detail to the preferred embodiments of the present
5 invention, examples of which are illustrated in the accompanying drawings, which are not
intended to limit scope of the present invention. Whenever possible, the same reference
numerals will be used throughout the description to refer to the same or like parts of the
invention.
10 The present invention aims at solving the problem of loading and holding hot
optical fiber preform and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby,
15 the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from one stage to another without manual intervention.
Now referring to Figure 1, in accordance with preferred embodiment of the present invention the novel mechanism 101 for loading and holding hot optical fiber
20 preform and precursors thereof comprises a pair of arms 103, both held at first ends 103a onto a support bar 105 by means of clamp 106 (which may be circular or rectangular or square depending upon the shape of support bar 105). The clamp 106 is of diameter or dimensions slightly greater than that of the support bar 105. The clamp 106 slides along the support bar 105 and fixed onto the support bar 105 with the help of screw 107. A
25 support member 104 secure each of the arm of the pair of arms 103 from longitudinal or lateral stress. The support bar 105 is made of one of the metals out of the group of metals including stainless steel, aluminum etc and have grooves 113 so that the pair of arms 103 with the help of clamp 106 can slide along the support bar 105. The support bar 105 is attached to another support, referred to as support frame 109 in such a way that the
30 support bar 105 can be rotated through 360 degree in both clockwise and anticlockwise direction shown by arrow 108. The option of rotation of the support bar 105 helps in
13 Agent Docket No: BL/PAT/IN/085/001

holding and removing the optical fiber preform and the precursors thereof from the any deposition machine where the deposition is done in either vertical and/or horizontal direction. The support frame 109 is positioned onto a flat platform 111 with wheels 112. The second ends 103b of the arm pair 103 are provided with gripping jaws 102. The
5 gripping jaws 102 are either cup-shaped or parabola shaped or bowl shaped or a combination thereof and are provided with a passage 204 (figure 2A and 2C) of diameter slightly greater than the diameter of optical fiber preform handle so that the handles 405 or 702 or 802 (figure 4, figure 7 and figure 8) can pass through. The gripping jaws 102 do not have any moving parts. The advantage of these immovable gripping jaws 102 is that
10 operations are easy and fail proof. The pair of arms 103 is loaded onto the support bar 105 such that the bottom 102a of the gripping jaws 103 faces each other (Figure 1 and Figure 2B).
Figure 2 A illustrates the schematic top view of the bowl shaped gripping jaw 102
15 in accordance with one embodiment of the present invention. The gripping jaw 102 comprises of a bowl shaped body 201, with the base 203 of the bowl 201 flat (figure 2B and figure 2C), the base 203 and the bowl 201 are cut so as to form the passage 204. The diameter of passage 204 is slightly greater than that of the handle 405/702/802 of the optical fiber preform and precursors thereof so that the handle 405/702/802 can be slide
20 in. The gripping jaw 102 can be attached to the arms 103 by screwing or welding. Figure 2B illustrates the cross-sectional view of the gripping jaw 103 in accordance with the present invention. The gripping jaw 102 has two sides namely, the bottom 102a and the top 102b (figure 2B). Figure 2C illustrates a three-dimensional view of the gripping jaw 102 in accordance with one embodiment of the present invention.
25
It has been observed that the gripping jaws 102 or 302 of the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention are without any moving parts and has the advantage of being easy to operate, hold the optical fiber preform and without fear of slipping of the optical fiber preform
30 and precursors thereof, during the holding and transfer from one stage to another.
14 Agent Docket No: BL/PAT/IN/085/001

In accordance with the present invention the gripping jaw 102 or 302 can be made up of any material that is non-corrosive and capable of bearing high temperature and weight of the optical fiber preform and precursors thereof.
5 In accordance with one embodiment of the present invention the gripping jaw 102
or 302 can be made up of one of the metals out of the group of metals including stainless steel, aluminum etc coated with teflon.
In one embodiment the gripping jaw 102 or 302 can be cup-shaped or parabola 10 shaped according to the need.
Now referring to figure 3 and figure 4 the working of the mechanism 301 for loading and holding the hot optical fiber preform and precursors thereof is explained. In accordance with the present invention the mechanism for loading and holding the optical
15 fiber preform or precursors thereof, is moved near to the optical fiber preform or the precursors thereof. One of the arms out of the pair of arms 303 with the gripping jaws 302 is positioned and fixed using a clamp 306, at the lower end of the support bar 305 while the other arm out of the arm pair 303, which is movable, is positioned at upper end of the support bar 305. One conical end 401b of the optical fiber preform 401 or the
20 precursors thereof with the glass handle 405, are positioned in the gripping jaw 302 of the arm positioned at the lower end of the support bar 305. The other conical end 401a of the optical fiber preform or precursors thereof is the capped with the second gripping jaw 302 of the other arm 303 by sliding the arm in vertically downward direction and then clamping the arm with screw 307 of the clamp 306. When the arm is just near the conical
25 part 401 a of the optical fiber preform 401, the handle 405 of the optical fiber preform 401 is slide through the passage 204 in the gripping jaw 302 of the upper arm. There after the arm is slide in the vertically downward direction so as to cover or cap the conical shape 401a of the optical fiber preform 401 (as shown in figure 3) completely. Since the gripping jaw 302 is either cup-shaped or parabola shaped or bowl shaped or a
30 combination thereof, once the cup shape covers the conical part 401a or 401b the optical fiber preform or precursors 401 thereof are gripped and because of the cup-shape or the
15 Agent Docket No: BL/PAT/IN/085/001

parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances.
In accordance with one embodiment all the operations described above may be
5 executed in an automated manner or manually using the mechanism for loading and holding the hot optical fiber preform or precursors thereof of the present invention, wherein the mechanism for loading and holding the hot optical fiber preform or precursors thereof of the present invention is provided with electromechanical devices (not shown in figure) for carrying out the operations such as rotation of the support bar
10 305, the movement of the whole mechanism 301, the sliding movement of the arms 303 and so on, in case if the operations are executed in an automated manner. Such automation that is, carrying out of operations such as rotation of the support bar 305, the movement of the whole mechanism 301 the sliding movements of the arms 303 are available commercially.
15
In accordance with present invention the mechanism for loading and holding the hot optical fiber preform and the precursors thereof can be used at various stages of manufacturing of the optical fiber preform and precursors thereof.
20 In one embodiment the mechanism of the present invention can be used to remove
the soot porous body after completion of soot deposition on the cylindrical member the soot preform is removed from the deposition machine.
In another embodiment the mechanism of the present invention can be used to
25 load, hold and transfer the soot porous body from which the sintered mother preform can be made or the sintered mother preform or the soot porous body after overcladding or the sintered daughter preform and so on. The optical fiber preform and the precursors thereof can be immediately transferred in hot condition from one stage to another, meaning thereby, the need for cooling the optical fiber preforms and the precursors thereof to
30 room temperature in any stage is eliminated. Thus, the mechanism can be used to hold
16 Agent Docket No: BL/PAT/IN/085/001

and transfer the optical fiber preform and the precursor thereof even when they are hot, meaning thereby, the process time can be shorten or reduced.
Figure 4 illustrates an exemplary soot deposition machine 407, wherein, the core
5 portion of the optical fiber preform and part of the cladding is deposited by Atmospheric Chemical Vapor Deposition (ACVD) method, wherein the soot is deposited on the cylindrical member 403 (also referred as target rod or mandrel) with a hollow glass handle 405 intact, which is used for ease of handling the soot porous body 402 so formed. In this method, the deposition of soot 409 is accomplished by traverse motion of the
10 cylindrical member 403 over the burner(s) 408 or vice versa, while rotating the cylindrical member 403 (rotation indicated by the arrow 406). The burner(s) 408 are supplied with silicon containing materials (for example, silicon tetrachloride), gases supporting oxidation (for example oxygen) and heat producing gases (for example hydrogen, methane etc) (not shown in the figure). The oxidation of silicon containing
15 materials takes place-forming oxides of silicon, which is generally referred to as soot 409. The initial soot deposition comprises dopant chemicals to increase refractive index of the core and dopant chemicals are terminated after desired core diameter is obtained. The deposition process continues until the required dimension of the soot porous body 402 is attained for meeting desired core diameter in the optical fiber preform and the
20 desired core-clad diameter ratio in the fiber. After completion of soot deposition, the soot porous body can be removed from the soot deposition machine 407 without need for cooling down to room temperature, held and transferred to storage cabin by using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention. The cylindrical member 403 is removed from the soot
25 porous body 402, after cooling the soot porous body 402 to room temperature, to form hollow soot porous body 501 defining a capillary 502 at the center [herein after referred to as hollow soot porous body]. Figure 5A and Figure 5B illustrates the cross-sectional and longitudinal view of the hollow soot porous body 501 comprising the capillary 502, the core part 503 and the part of cladding 504.
30
17 Agent Docket No: BL/PAT/IN/085/001

The hollow soot porous body 501 so formed by the ACVD method contains large amount of hydroxyl group or water as generally referred to. In order to remove the hydroxyl content of the hollow soot porous body 501, it is treated with gases, which chemically reacts with the hydroxyl group. Halogens or compounds of halogen are
5 generally used for such purpose. This step of removing the hydroxyl content from the hollow soot porous body is known as dehydration or drying. In this step of dehydration or drying at first a glass plug is inserted into the end remote from the handle of the hollow soot porous body. The cooled hollow soot porous body 501 is moved into a furnace 601, suspended by the hollow handle 405 in the furnace 601, wherein this hollow soot porous
10 body 501 is heated at a temperature of about 1050°C in an atmosphere of gases of halogens or compounds thereof to remove the hydroxyl content for a predetermined duration of time. Thereafter the dehydrated hollow soot porous body 501 is sintered to form a glass preform in an atmosphere of gases of halogens or compounds thereof at a temperature of about 1500°C. This step of sintering of hollow soot porous body in to
15 glass is also known as vitrification or consolidation.
Figure 6 illustrates the dehydration and sintering furnace 601 for dehydration and sintering of the hollow soot porous body 501. A glass plug 608 is inserted into the end remote from the handle 405 of the hollow soot porous body 501. The cooled hollow soot
20 porous body 501 is inserted into dehydration and sintering furnace 601, suspended by the hollow handle 405 in the sintering furnace, wherein this hollow soot porous body 501 is first dehydrated at a temperature of about 1050°C and then sintered (also known as vitrification or consolidation) in a chlorine and helium atmosphere to form optical fiber preform at about 1500°C. The dehydration and sintering is preferably carried out in the
25 same furnace to avoid contamination of dehydrated hollow soot porous body 501. The dehydration and sintering furnace 601 is specially built for the purpose equipped with one or more heating elements 604 and gas inlets 602 and reaction product-scrubbing outlet 603. The hollow soot porous body 501 is suspended in the dehydration and sintering furnace 601 by the suspension device 607. The dehydration and sintering processes
30 comprise inserting the hollow cylindrical soot porous body 501 into a sintering furnace 601 and subjecting it to a temperature regime under controlled chemical environment to
18 Agent Docket No: BL/PAT/IN/085/001

form sintered glass preform sequentially. The chemical environment necessary for dehydration is provided with the help of gases that promote dehydration. The chemical environment that is necessary for sintering is provided with gases that are inert and have high thermal conductivity. The gases are provided through the inlet 602 and scrubbed
5 through the upper outlet 603. The sintering furnace is covered at the top with a plate 606 that avoids the ingress of atmospheric air into the furnace and leakage of gases inside the furnace into the environment.
The capillary 502 in the hollow soot porous body is collapsed either during the
10 sintering step or after the sintering step. The collapse of the capillary 502 takes place
under vacuum. A tube 609 is attached to the hollow handle 405 and is connected to
vacuum pump. There after the sintered glass preform (also called as mother preform),
after removal from the sintering furnace 601 is held and transferred to the rod draw
furnace by using the mechanism of the present invention for holding the optical fiber
15 preform and precursors thereof without need for cooling down to room temperature,
(Figure 2), wherein it is subjected to a process step of rod draw to form a plurality of core
rods having predetermined diameter. Optical fiber can also be drawn from the mother
preform at this stage. In this case the mother preform is held and transferred to the optical
fiber drawing furnace, by using the mechanism for loading and holding the hot optical
20 fiber preform and the precursors thereof of the present invention to the optical fiber, in
hot condition without need for cooling down to room temperature.
Figure 7 depicts the core rod assembly 701 prepared by heat welding glass handles 702 to both the ends of core rod 703 obtained by drawing mother preform. The
25 core rod assembly is subjected to a step of over cladding thereafter. The core rod assembly 701 after preparation is hot and can be held and transferred to the deposition machine, similar to the deposition machine 407, for overcladding the core rod assembly, by using the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention.
30
19 Agent Docket No: BL/PAT/IN/085/001

The core rod assembly 701 is placed inside the deposition machine, wherein soot is deposited onto the core rod assembly 701 using burners similar to that used for preparation of mother perform to form soot porous body 801 (Figure 8). This step of depositing soot over the core rod is called overcladding. The soot porous body 804
5 formed is then removed from the deposition machine, without need for cooling down to room temperature, it is held and transferred, using the mechanism for loading and holding the hot optical fiber preform and precursors thereof of the present invention, to a dehydration and sintering furnace similar to that for dehydration and sintering hollow soot porous body. The temperature of the dehydration is about 1200°C and that of
10 sintering is about 1550°C.
The soot porous body suspended by the glass handles 802, to form what is known
as daughter preform. Again without need for cooling down to room temperature, it is held
and transferred to the optical fiber draw furnace using the mechanism for loading and
15 holding the hot optical fiber preform and the precursors thereof of the present invention,
to draw optical fiber therefrom.
In accordance with the present invention the mechanism for loading and holding the hot optical fiber preform and the precursors thereof can be used to handle the optical
20 fiber preform and precursors thereof, safely and can also be transferred from one stage to another or from one stage to the storage and transportation device of US' 613, though at every stage of the optical fiber preform manufacturing process the temperature of the optical fiber preform and the precursors thereof is high, typically the temperature is in the range of about 800°C to about 1600°C or more.
25
The various parts of the mechanism for loading and holding hot optical fiber preform and precursors thereof of the present invention are made of metals out of the group of metals including stainless steel, aluminum etc preferably coated with teflon.
30 It is observed that not only hot but it is also possible to load, hold and transfer
bulky optical fiber preforms and precursors thereof to increase production and reduce
20 Agent Docket No: BL/PAT/IN/085/001

manufacturing cost. Using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the optical fiber preform and precursors thereof, for example, in the order of 20 kg or more and length of a meter or more, can be safely, easily and without any human intervention transferred from one
5 stage to another.
In accordance with the present invention using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the limitation of the device of US '613 for storage and transportation of optical fiber
10 preform and precursors thereof, of necessity to cool the optical fiber preform and precursors thereof is eliminated as the hot optical fiber preform and precursors thereof can be held and transferred from one stage to another using combination of the mechanism of the present invention and the device of US '613.
15 In accordance with the present invention the manual handling of the optical fiber
preform and the precursors thereof and the possibility of human error leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling is eliminated by using the novel mechanism of the for loading and holding the hot optical fiber preform and precursors thereof.
20
In accordance with the present invention the mechanism for loading and holding hot optical fiber preform and precursors thereof eliminates the problem of damage or contamination of the optical fiber preform or precursors thereof, which may occur during handling or transferring of the same and which in turn may result in an optical fiber with
25 low tensile strength or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom that renders the optical fiber obtained therefrom unsuitable for desired applications .

In accordance with the present invention the necessity to cool the optical fiber
30 preform and precursors thereof to room temperature, is eliminated completely, so that they can be handled safely.
21 Agent Docket No: BL/PAT/IN/085/001

One advantage of the present invention is that about 15% of the total optical fiber
manufacturing process time is saved, by making it possible to hold and transfer the
optical fiber preform and precursors thereof in hot conditions at various stages using the
5 mechanism for loading and holding the hot optical fiber preform and the precursors
thereof of the present invention.
Another advantage of the present invention is that the constraint of cooling the optical fiber preform and precursors thereof to room temperature, is eliminated, meaning
10 thereby, the overall process time and hence the cost of the optical fiber manufacturing process is reduced.
It is also an advantage of using the mechanism for loading and holding hot optical fiber preform or precursors thereof of the present invention the possibility of human error
15 leading to damage or complete loss of the optical fiber preform and the precursors thereof due to falling is eliminated.
Further it is observed that using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention is not at all
20 complicated.
Further it is observed that by using the mechanism for loading and holding the hot optical fiber preform and the precursors thereof of the present invention the problem of damages or contamination to the surfaces of optical fiber preform and the precursors
25 thereof which in turn may result in an optical fiber breaks or undesired optical parameters, for example attenuation of the optical fiber, being drawn therefrom is eliminated.
22 Agent Docket No: BL/PAT/IN/085/001

What is claimed is:
1. A mechanism (101) for loading and holding hot optical fiber preform and
precursors thereof, the mechanism comprise:
5 a. a support bar (105) to support a pair of arms (103) at one end (103a);
b. a pair of arms (103), to hold optical fiber perform and precursors thereof,
each arm having a clamp (106) arrangement at one end, each clamp (106)
having a screw (107), each of said clamps (106) being shaped in such a
way so as to slide along said support bar (105) and to get fixed onto said
10 support bar (105) when said screw (107) of the said clamp (106) is
tightened;
c. a support member (104) to secure each of the arm of said pair of arms
(103) from longitudinal or lateral stress;
d. a support frame (109), said support bar (105) being connected to said
15 support frame (109) in a manner so as to allow 360 degree rotation of said
support bar (105) in both clockwise and anticlockwise direction, so as to allow loading, holding and removing of optical fiber preform and precursors thereof in vertical, horizontal or any angular position;
e. a flat platform (111) with wheels (112), to position the support frame
20 (109) to enable easy movement of said mechanism (101); and
f. a gripping jaw (102) at the second end (103b) of each of said pair of arms
(103),
where said support bar (105) has grooves (113) so that the pair of arms with the help of
25 clamp (106) can slide along the support bar (105) and where the pair of arms (103) are loaded onto the support bar such that the gripping jaws face (102a) each other.
2. Mechanism (101) as in claim 1, where the clamps (106) are circular in shape;
30 3. Mechanism (101) as in claim 1, where the clamps (106) are rectangular in shape;
23 Agent Docket No: BL/PAT/N/085/001

4. Mechanism (101) as in claim 1, where the clamps (106) are square in shape;

5
10

5. Mechanism (101) as in claim 1, the mechanism (101) further comprising electromechanical means to enable control of the movements of said mechanism.
6. Mechanism (101) as in claim 1, where the support bar (105) is made of one of the metals out of the group of metals including stainless steel, aluminum or iron.
7. Mechanism (101) as in claim 1, where the gripping jaws (102) are cup-shaped
8. Mechanism (101) as in claim 1, where the gripping jaws (102) are parabola shaped
9. Mechanism (101) as in claim 1, where the gripping jaws (102) are bowl shaped

15 10. Mechanism (101) as in claim 1, where the gripping jaws (102) are provided with a passage (204) of diameter slightly greater than the diameter of optical fiber preform handle (405/702/802) so that the handles (405/702/802) can pass through.
11. Method for loading and holding the hot optical fiber preform or precursors thereof,
20 using a mechanism (101) as claimed in claim 1, the method comprising the steps of:
a. having one of the arms out of the pair of arms (3 03) with the gripping jaws
(302) positioned and fixed using a clamp (306) at the lower end of the
support bar (305);
b. positioning the second arm out of the arm pair (303) using the sliding
25 clamp (306) at the upper end of the support bar (305);
c. positioning in the gripping jaw (302) of the arm positioned at the lower
end of the support bar (305) one conical end (401b) of the optical fiber
preform or the precursors thereof with the glass handle;
d. capping the other conical end (401a) of the optical fiber preform or
30 precursors (401) thereof with the second gripping jaw (302) of the other
arm by sliding the arm in vertically downward direction;
24 Agent Docket No: BL/PAT/IN/085/001

e. sliding the handle (405) of the optical fiber preform or precursors thereof
(401) through the passage (204) in the gripping jaw (302) of the upper arm
so as to cover the conical shape (401a) of the optical fiber preform; and
f. clamping the arm with the clamp (306);
5 where the gripping jaw (302) is either cup-shaped or parabola shaped or bowl
shaped or a combination thereof, once the cup shape covers the conical part the optical fiber preform or precursors thereof are gripped and because of the cup-shape or the parabola or the bowl shape the optical fiber preform or the precursors thereof cannot move or slip out in any circumstances and where said mechanism for loading and holding
10 the hot optical fiber preform and the precursors thereof can be used at various stages of manufacturing of the optical fiber preform and precursors thereof.
12. Method as in claim 11, where the method can be used to remove the soot porous body
after completion of soot deposition on the mandrel the soot preform is removed from
15 the deposition machine.
13. Method as in claim 11, where the method can be used to hold and transfer the soot
porous body from which the sintered mother preform can be made or the sintered
mother preform or the soot porous body after overcladding or the sintered daughter
20 preform and so on.
14. Method as in claim 11, where the steps of the method are performed in an automated
manner.
25 Agent Docket No: BL/PAT/IN/085/001

Abstract
A novel mechanism for holding hot optical fiber preform and precursors thereof is disclosed. The present invention solves the problem of holding hot optical fiber preform
5 and precursors thereof and reducing the manufacturing time of the optical fiber preform and precursors thereof, by about 15%, and thus the manufacturing cost of the optical fiber preform and precursors thereof, eliminating the need for cooling of the optical fiber preform and precursors thereof to room temperature, meaning thereby, the hot optical fiber preform and precursors thereof can be held and transferred safely and easily from
10 one stage to another without manual intervention.
26 Agent Docket No: BL/PAT/IN/085/001

Documents:

1528-MUM-2007-ABSTRACT(12-6-2012).pdf

1528-MUM-2007-ABSTRACT(18-7-2011).pdf

1528-MUM-2007-ABSTRACT(7-8-2012).pdf

1528-mum-2007-abstract.doc

1528-mum-2007-abstract.pdf

1528-MUM-2007-ASSIGNMENT(18-7-2011).pdf

1528-MUM-2007-CLAIMS(AMENDED)-(12-6-2012).pdf

1528-MUM-2007-CLAIMS(AMENDED)-(18-7-2011).pdf

1528-mum-2007-claims.doc

1528-mum-2007-claims.pdf

1528-mum-2007-correspondence(15-5-2008).pdf

1528-MUM-2007-CORRESPONDENCE(19-4-2012).pdf

1528-MUM-2007-CORRESPONDENCE(7-8-2012)-.pdf

1528-MUM-2007-CORRESPONDENCE(7-8-2012).pdf

1528-mum-2007-correspondence-received.pdf

1528-mum-2007-description (complete).pdf

1528-MUM-2007-DRAWING(18-7-2011).pdf

1528-mum-2007-drawings.pdf

1528-MUM-2007-FORM 1(18-7-2011).pdf

1528-MUM-2007-FORM 1(7-8-2012).pdf

1528-mum-2007-form 13(15-5-2008).pdf

1528-MUM-2007-FORM 13(7-8-2012).pdf

1528-MUM-2007-FORM 2(TITLE PAGE)-(12-6-2012).pdf

1528-MUM-2007-FORM 2(TITLE PAGE)-(18-7-2011).pdf

1528-MUM-2007-FORM 2(TITLE PAGE)-(7-8-2012).pdf

1528-MUM-2007-FORM 26(12-6-2012).pdf

1528-mum-2007-form 26(15-5-2008).pdf

1528-MUM-2007-FORM 26(18-7-2011).pdf

1528-MUM-2007-FORM 5(18-7-2011).pdf

1528-mum-2007-form-1.pdf

1528-mum-2007-form-18.pdf

1528-mum-2007-form-2.doc

1528-mum-2007-form-2.pdf

1528-mum-2007-form-26.pdf

1528-mum-2007-form-3.pdf

1528-mum-2007-form-5.pdf

1528-mum-2007-form-9.pdf

1528-MUM-2007-MARKED COPY(12-6-2012).pdf

1528-MUM-2007-MARKED COPY(18-7-2011).pdf

1528-MUM-2007-REPLY TO EXAMINATION REPORT(18-7-2011).pdf

1528-MUM-2007-REPLY TO HEARING (12-6-2012).pdf

1528-MUM-2007-SPECIFICATION(AMENDED)-(12-6-2012).pdf

1528-MUM-2007-SPECIFICATION(AMENDED)-(18-7-2011).pdf

1528-MUM-2007-SPECIFICATION(AMENDED)-(7-8-2012).pdf

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Patent Number

254036

Indian Patent Application Number

1528/MUM/2007

PG Journal Number

38/2012

Publication Date

21-Sep-2012

Grant Date

14-Sep-2012

Date of Filing

08-Aug-2007

Name of Patentee

STERLITE TECHNOLOGIES LIMITED

Applicant Address

E1,E2,E3, MIDC, WALUJ, AURANGABAD

Inventors:

#	Inventor's Name	Inventor's Address
1	SHAM NAGARKAR	E1,E2,E3, MIDC, WALUJ, AURANGABAD-431136,

PCT International Classification Number

C03B20/00,G02B6/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA