GB1568458A

GB1568458A - Connecting means for an optical system

Info

Publication number: GB1568458A
Application number: GB785978A
Authority: GB
Original assignee: Deutsche ITT Industries GmbH; ITT Industries Inc
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1977-03-02
Filing date: 1978-02-28
Publication date: 1980-05-29
Also published as: FR2382706A1; FR2382706B1; CH627002A5

Abstract

In order to be able in an optical system to connect a mixing tube in a separable fashion to a glass fibre cable, both the mixing tube holder, which has a tubular body (1) and a flange (2), and the connector, which has a tubular body (11) and a flange (12), are each equipped with an end piece (3 and 13, respectively) of the same diameter, in which end pieces a mixing tube end or a tubularly expanded glass fibre bundle are cemented in each case in a watch stone (4 and 14, respectively). An intermediate ring (23) precisely aligns the end pieces (3, 13) which are opposite one another and permits the two flanges to be screwed. <IMAGE>

Description

(54) CONNECTING MEANS FOR AN OPTICAL SYSTEM (71) We, ITT INDUSTRIES INC, a Corporation organised and existing under the Laws of the State of Delaware, United States of America, of 320 Park Avenue, New York 22, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention concerns connection means for an optical system and more especially a connecting device to provide coupling between a cable of optical fibers and a mixing device such as a tubular mixer.

According to the invention there is provided an arrangement for coupling an optical fibre bundle cable to a cylindrical optical mixer device, which includes a mixer support device and a connector device, wherein the mixer device includes a mixer support formed by a first cylindrical body with a coupling flange and a spigot-shaped end piece at each of its ends, a first axial bore extending from one end of the cylindrical body to the other end thereof, a counterbore at each end of the body, and a ring whose inside diameter is less than that of said first axial bore, said rings supporting a said cylindrical mixer device within the cylindrical body when the coupling arrangement is in use, and wherein the connector device includes a hollow cylindrical body terminated at one end by a coupling flange and a spigot-shaped end piece, wheren the last-named end piece has a counterbore for the reception of a ring whose inside diameter is equal to that of a said ring of the support, wherein when the device is in use the sheath of an optical fibre cable is attached to the other end of the connector device and the fibres of the bundle of fibres of the cable are arranged in a tubular bundle, cemented to the inside bore of the connector devices ring and held in place by a cylindircal or near-cylindrical core cemented to the inside of the tubular bundle of fibres, and wherein the mixer support and the connector device when in use are held in correct axial alignment by a space between the flange at one end of the mixer support and a flange at the same end of the connector device as its said ring and by demountable means for holding the said flanges together.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 represents an optical fiber mixing device; Figure 2 shows a cross-sectional view of a mixer support for use with the device of Figure 1; Figure 3 shows a variant of the mixer support shown in Figure 2; Figure 4 shows a cross-sectional view of a connector for coupling an optical fiber cable to the mixer of Figure 1: Figure 5 shows a cross-sectional view of the mixer support in Figure 2 joined to the connector in Figure 4; Figure 6 illustrates a methed of installing fibers in the connector Figure 7a and 7b show two possible core configurations used for the placement of fibers in the connector.

The mixer used in the arrangement to be described is shown in Figure 1. It consists of a cylindrical tube of a length L and thickness e, terminating in two plane faces P and P' perpendicular to the axis. made of a transparent material having a refractive index nl.

The inner and outer walls of the tube are in contact with a medium having a refractive index n2, lower than index nl. The end faces P and P' are placed in contact with optical fibers arranged in a tubular bundle with a single layer of fibers. If the length L of the mixer is sufficient, light energy received at face P through a fiber F1 is distributed uniformly over face P' and therefore between all the fibers F'k. Conversely, a fiber F'1 receives through the mixer an almost equal fraction of the light energy transmitted by all the fibers Fk.

A support for such a mixer is shown in Figure 2. It consists of a body 1 provided at each end with a coupling flange 2 and an end piece 3. An axial bore 6 extends longitudinally along the support and its diameter is greater than the diameter of the mixing device. Recesses are provided in the ends of the end pieces 3 for the insertion of mixer guide rings 4. Such a ring 4 is preferably a watch jewel. The hole in the jewel is bored to the dimension of the outside diameter of the mixer by any known method. Attachment holes 8 are drilled in the flanges 2. The mixer is held in place by cementing one of its ends to the inner wall of a jewel. If the mixer does not have an optical sheathing, it is best to coat its outer wall with a reflecting film to prevent the light losses on contact with the cement or the jewel. A hole 7 is drilled in body 1 tio allow a synthetic resin to be poured into the free space between the mixer 5 and the body 1 and serving to lock the mixer in place. If the mixer does not have an optical sheathing, a transparent synthetic resin should be used having a refractive index n3 low enough to allow it to serve as an optical sheating. The numerical aperture NA of the mixer can then be written

In order to have no light loss, this numerical aperture must be greater than that of the optical fibers in contact with the end faces of the mixer. The mixer support will be preferably made of a material having an expansion factor as close as possible to that of the mixer glass. After the mixer is cemented, its ends are cut off and the faces of the end pieces are ground to an exact dimension and polished.

Figure 3 shows a variant of the support in Figure 2. The body 1 of the support is divided into two parts 1 and 1' in order that the length of the support can be matched to the length of the mixer. Once the mixer 5 is in place, the two parts of the mixer support 1 and I' are fastened together by means of a sleeve 10. The assembly is held together by means of an "epoxy" type or cyanoacrylic cement.

Figure 4 shows a cross-sectional view of a connector for coupling an optical fiber cable to a mixer. The connector consists of a body 11, a coupling flange 12 and an end piece 13.

As in the case of the support shown in Figure 2, a guide ring 14 is set in a recess provided for this purpose in the end of the end piece 13. The guide ring 14 (or jewel) is bored to the same diameter and with the same precision as in the case of the mixer support. The optical cable 20 is held in place by cementing to a sleeve 21, for example, of a thermosetting material. The sleeve 21 can be fixed to the body 11 also by cementing it to a knurled section 22 located at the end of the body 11. The optical fibers are arranged in a tubular bundle 15 of one or more layers and cemented to the inner wall of the jewel 14. They are held in place by a core 19 while the core-fiber assembly is cemented firmly.

As in the case of the support in Figure 2, the end face of the connector is ground to the desired dimension and polished. This end face must be parallel to the front face of the flange 12. Attachement holes 18 are drilled in the flange 12.

Figure 5 shows a cross-sectional view of the connector in Figure 4 and the support in Figure 2 when they are assembled together.

The connector and support are positioned and aligned axially by means of a spacer 23 in which a hole has been bored of the same diameter as the ouside diameter of the connector and support end pieces. Holes are provided in the spacer 23 for the installation of screws 24 which hold the connectorspacer-support assembly together. Grooves 25 are provided on the support and on the connector respectively for the installation of O-rings which seal the assembly.

Figure 6 illustrates a method for positioning fibers in the bore of the connector jewel.

A notched disk 26 holds the fibers projecting from the connector in position. A tapered core 28, of drawn glass for example, is lowered through a center hole 27 drilled in the disk 26 into the free space in the middle of the fibers. If a single layer of fibers is sufficient, the fibers will be properly positioned by rotating the core back and forth as it is lowered into place. The core is then pushed in until it bottoms and is cemented in place with the fibers. The fibers and core projecting outward past the connector end piece 13 are then severed and the front face of the end piece is ground and polished as previously indicated. If several layers of fibers are required, it is preferably to use a core such as the one whose cross-section is shown in Figure 7.b. It differs from the core previously used, whose cross-section is shown in Figure 7.a, in that it is designed with ribs which serve to divide the bundle of fibers into equal fractions. The fibers are then positioned in the same way as before.

WHAT WE CLAIM IS: 1. An arrangement for coupling an optical fibre bundle cable to a cylindrical optical mixer device. which includes a mixer support device and a connector device, wherein the mixer device includes a mixer support formed by a first cylindrical body with a coupling flange and a spigot-shaped

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. distributed uniformly over face P' and therefore between all the fibers F'k. Conversely, a fiber F'1 receives through the mixer an almost equal fraction of the light energy transmitted by all the fibers Fk. A support for such a mixer is shown in Figure 2. It consists of a body 1 provided at each end with a coupling flange 2 and an end piece 3. An axial bore 6 extends longitudinally along the support and its diameter is greater than the diameter of the mixing device. Recesses are provided in the ends of the end pieces 3 for the insertion of mixer guide rings 4. Such a ring 4 is preferably a watch jewel. The hole in the jewel is bored to the dimension of the outside diameter of the mixer by any known method. Attachment holes 8 are drilled in the flanges 2. The mixer is held in place by cementing one of its ends to the inner wall of a jewel. If the mixer does not have an optical sheathing, it is best to coat its outer wall with a reflecting film to prevent the light losses on contact with the cement or the jewel. A hole 7 is drilled in body 1 tio allow a synthetic resin to be poured into the free space between the mixer 5 and the body 1 and serving to lock the mixer in place. If the mixer does not have an optical sheathing, a transparent synthetic resin should be used having a refractive index n3 low enough to allow it to serve as an optical sheating. The numerical aperture NA of the mixer can then be written In order to have no light loss, this numerical aperture must be greater than that of the optical fibers in contact with the end faces of the mixer. The mixer support will be preferably made of a material having an expansion factor as close as possible to that of the mixer glass. After the mixer is cemented, its ends are cut off and the faces of the end pieces are ground to an exact dimension and polished. Figure 3 shows a variant of the support in Figure 2. The body 1 of the support is divided into two parts 1 and 1' in order that the length of the support can be matched to the length of the mixer. Once the mixer 5 is in place, the two parts of the mixer support 1 and I' are fastened together by means of a sleeve 10. The assembly is held together by means of an "epoxy" type or cyanoacrylic cement. Figure 4 shows a cross-sectional view of a connector for coupling an optical fiber cable to a mixer. The connector consists of a body 11, a coupling flange 12 and an end piece 13. As in the case of the support shown in Figure 2, a guide ring 14 is set in a recess provided for this purpose in the end of the end piece 13. The guide ring 14 (or jewel) is bored to the same diameter and with the same precision as in the case of the mixer support. The optical cable 20 is held in place by cementing to a sleeve 21, for example, of a thermosetting material. The sleeve 21 can be fixed to the body 11 also by cementing it to a knurled section 22 located at the end of the body 11. The optical fibers are arranged in a tubular bundle 15 of one or more layers and cemented to the inner wall of the jewel 14. They are held in place by a core 19 while the core-fiber assembly is cemented firmly. As in the case of the support in Figure 2, the end face of the connector is ground to the desired dimension and polished. This end face must be parallel to the front face of the flange 12. Attachement holes 18 are drilled in the flange 12. Figure 5 shows a cross-sectional view of the connector in Figure 4 and the support in Figure 2 when they are assembled together. The connector and support are positioned and aligned axially by means of a spacer 23 in which a hole has been bored of the same diameter as the ouside diameter of the connector and support end pieces. Holes are provided in the spacer 23 for the installation of screws 24 which hold the connectorspacer-support assembly together. Grooves 25 are provided on the support and on the connector respectively for the installation of O-rings which seal the assembly. Figure 6 illustrates a method for positioning fibers in the bore of the connector jewel. A notched disk 26 holds the fibers projecting from the connector in position. A tapered core 28, of drawn glass for example, is lowered through a center hole 27 drilled in the disk 26 into the free space in the middle of the fibers. If a single layer of fibers is sufficient, the fibers will be properly positioned by rotating the core back and forth as it is lowered into place. The core is then pushed in until it bottoms and is cemented in place with the fibers. The fibers and core projecting outward past the connector end piece 13 are then severed and the front face of the end piece is ground and polished as previously indicated. If several layers of fibers are required, it is preferably to use a core such as the one whose cross-section is shown in Figure 7.b. It differs from the core previously used, whose cross-section is shown in Figure 7.a, in that it is designed with ribs which serve to divide the bundle of fibers into equal fractions. The fibers are then positioned in the same way as before. WHAT WE CLAIM IS:

1. An arrangement for coupling an optical fibre bundle cable to a cylindrical optical mixer device. which includes a mixer support device and a connector device, wherein the mixer device includes a mixer support formed by a first cylindrical body with a coupling flange and a spigot-shaped

end piece at each of its ends, a first axial bore extending from one end of the cylindrical body to the other end thereof, a counterbore at each end of the body, and a ring whose inside diameter is less than that of said first axial bore, said rings supporting a said cylindrical mixer device within the cylindrical body when the coupling arrangement is in use, and wherein the connector device includes a hollow cylindrical body terminated at one end by a coupling flange and a spigot-shaped end piece, wherein the last-named end piece has a counterbore for the reception of a ring whose inside diameter is equal to that of said ring of the support, wherein when the device is in use the sheath of a optical fibre cable is attached to the other end of the connector device and the fibres of the bundle of fibres of the cable are arranged in a tubular bundle, cemented to the inside bore of the connector devices ring and held in place by a cylindrical or near-cylindrical core cemented to the inside of the tubular bundle of fibres, and wherein the mixer support and the connector device when in use are held in correct axial alignment by a spacer between the flange at one end of the mixer support and a flange at the same end of the connector device as its said ring and by demountable means for holding the said flanges together.

2. An arrangement as claimed in claim 1, and wherein the optical cable sheath is attached, when the arrangement is in use. to said other end of the connector device by a sleeve of a thermosetting material fixed to one end of said conector device and to the cable sheath.

3. A detachable arrangement for connecting a fiber optic bundle and an optical mixing device, the mixing device comprising: a support including a cylindrical body with a coupling flange and a spigot-shaped end piece at each end thereof, an axial bore extending to the ends of said body, a counterbore in each of said end pieces, a ring mounted in each said counterbore, each said ring having an inside diameter less than that of said axial bore; a cylindrical optical mixing device extending axially in said bore and having an outside diameter equal to the inside diameter of said rings, the ends of said mixing device being mounted in said rings; a cable terminator comprising a hollow cylindrical body terminated at one end by a coupling flange and a spigot-shaped end piece, said end piece having a further counterbore therein, a further ring mounted in said further counterbore and having an inside diameter equal to that of the end ring of said support, a fiber optic bundle mounted in said connector, means positioning the fibers of said bundle in an annular array inside the bore of said further ring, which means comprises a cylindrical core secured to the inside of said annular array of fibers; means for aligning centre axes of said mixing device and said cable termination, said aligning means being located between the outer faces of the coupling flanges of said mixing device and said cable tcrmination, said aligning means having a length such that the end piece faces of said mixing device and said connector can be brought very close together; and detachable means for holding together the coupling flanges of said connector and mixing device and said aligning means.

4. An optical fiber connection arrangement substantially as described herein with reference to Figures 4 to 7 of the accompanying drawings.