GB2158605A - Optical fiber coupling device - Google Patents
Optical fiber coupling device Download PDFInfo
- Publication number
- GB2158605A GB2158605A GB08510894A GB8510894A GB2158605A GB 2158605 A GB2158605 A GB 2158605A GB 08510894 A GB08510894 A GB 08510894A GB 8510894 A GB8510894 A GB 8510894A GB 2158605 A GB2158605 A GB 2158605A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optical fiber
- lens
- light beam
- laser beam
- path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/422—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements
- G02B6/4226—Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4206—Optical features
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4248—Feed-through connections for the hermetical passage of fibres through a package wall
Abstract
A laser beam 10 focussed by a lens 14B is centered on the exposed end of an optical fiber 13 and passes through a glass disc 36 capable of refracting the light beam.The glass disc 36 is mounted on a plate 38 capable of being tilted by screws 46 against the effect of springs 44. Tilting of the glass disc alters the position of the light beam 10 applied to the optical fiber by the refraction occurring in the glass disc so as to center the light beam on the exposed end of the fiber. <IMAGE>
Description
SPECIFICATION
Optical fiber coupling device
The present invention relates to an improved device for coupling a light source, such as a helium neon laser, to an optical fiber. With the coupling so provided the laser light may be converyed along the optical fiber.
A helium neon laser produces a visible, red, low divergence beam of laser light with a beam diameter typically about 0.8mm. It is often desired to couple the laser beam to an optical fiber device to transmit the laser light ot a location remote from the laser. This may occur, for example, when insufficient space exists to directly mount the laser, and associated power and control apparatus.
An optical fiber consists of a core of glass concentric with the axis of the fiber surrounded by a glass cladding. The core of glass has a slightly higher index of refraction than does the surrounding glass cladding.
Light entering one end of the optical fiber is guided to the other end with little loss in intensity because of the total internal reflection at the boundary between the high index of refraction core and the lower index of refraction cladding. A typical optical fiber has a diameter of approximately 0.125mm. The core typically has a diameter of 0.05 mm. The fiber is encased in a flexible sheath for ease of handling and to protect the fiber.
The resulting optical fiber cable is approximately 3 mm in diameter.
To facilitate installation and servicing of the cable, it ususally terminates, at each end, with connectors that plug into mating receptacles in the associated equipment. The connectors and receptacles place the end of the optical fiber in association with the portions of the optical system at either end of the cable that supply or receive the light transmitted by the optical fiber. The axial position, or spacing, of the optical fiber to the other portions of the optical system is also established.
In order to achieve effective coupling of a laser or other light beam to an optical fiber, the light must enter the core of the fiber within a narrow cone of acceptance concentric with the axis of the fiber. The angle of this cone is specified as the numerical aperture of the fiber. Because the core of the optical fiber is so much smaller than the diameter of the incoming laser beam, the beam diameter must be reduced prior to application to the optical fiber by passing it through a positive focal length lens. After passing through the lens, the beam diminishes in diameter to produce a cone of light having its apex at the focal point of the lens.
The beam then expands in a conical configuration beyond the focal point of the lens. The result is an accentuated hour glass shape for the beam having a small diameter beam waist in proximity to the focal point.
By proper choice of lens focal length, the bean waist can be made smaller than the core of the optical fiber, enabling almost all of the light to enter the optical fiber core. For this to occur, the exit rays of light from the lens must lie within the cone of acceptance of the fiber, the beam waist must be centered on the axis of the fiber, and the lens focal point must fall on the end of the core of the fiber.
It will be appreciated, given the small dimensions involved, that these criteria present a difficult problem in mechanical alignment. The problem is particularly difficult where an optical fiber cable terminates with plug-in connectors that permit removal and reinsertion of the optical fiber cable in receptacles in the other portions of the optical system or the replacement of one cable with another cable. With plug-in connectors, the connectors may not be inserted in the receptacles in exactly the same manner each time and the connectors and receptacles will wear in the course of repeated insertions. With the exchange of one cable for another, maufacturing tolerances may alter the positioning obtained by the connector.
For these reasons, an alignment system is oten provided in conjunction with the connector and receptacle at the ends of the cable to obtain the desired relative positioning between the beam of light and the optical fiber. Existing alignment systems commonly employ a lens having a fixed location with respect to the path of the light beam. The end of the optical fiber is then moved normal to the light transmission path by a complicated sliding means to provide the desired alignment. Another method moves the optical fiber through an arc by a form of ball and socket joint to bring the end of the optical fiber into alignment with the light beam.
However, both of these methods are mechanically complex. Further, they lack repeatibility, stability, and high resolution of adjustment. For these and other reasons, they have failed to completely solve the problem of coupling a beam of light, such as a laser beam, to the optical fiber in an optimum manner.
It is, therefore, the object of the present invention to provide an improved means for aligning an optical fiber with a light beam to enhance the coupling between the fiber and the light beam.
According to the present invention a coupling device for use between a light beam and the end of an optical fiber comprises a transparent means capable of refracting the light beam placed along the path of the light beam exterior to the optical fiber and through which the light beam passes, the transparent means being spaced from the end of the optical fiber and means for tititing the transparent means out of a position normal to the path of the light beam for altering the position of the light beam with respect to the end of the optical fiber as a result of the refraction occurring in the transparent means as the light beam passes therethrough.
The invention will be further understood by the following detailed description and accompanying drawings. In the drawings:
Figure 1 is a diagrammatic view of one prior form of apparatus for coupling a light beam to an optical fiber;
Figure 2 is a diagrammatic view of another prior form of such apparatus;
Figure 3 is a diagrammatic sectional view of a device according to the present invention for coupling a light beam to an optical fiber;
Figure 4 is a detailed diagrammatic view of a tilting transparent plate portion of the coupling device of
Figure 3, showing its operation;
Figure 5 is a detailed diagrammatic view of the tilting transparent plate portion showing a mathematical analysis of the improved coupling device; and
Figure 6 is a diagrammatic view taken along the line 6-6 of Figure 3 showing means for tilting the transparent plate portion.
In Figure 1, the numeral 10 indicates a light beam such as that produced by a helium neon laser, not shown.The numeral 12 indicates an optical fiber cable containing optical fiber 13 in sheath 15. To couple laser beam 10 to optical fiber 13, the beam is passed through positive focal length lens 14 to produce the hour glass shape described above having an angle of convergence less than the cone of acceptance of the optical fiber and having the small diameter waist at the lens focal point. Lens 14 or optical fiber 13 is positioned along the axis of laser beam 10 so that the focal point of the lens falls on the end of optical fiber 13.Optical fiber cable 12 is placed in holder 16 that can be moved normal to the axis of laser beam 10 to center the beam waist on the axis of optical fiber 13. Holder 16, mounted in frame 18 is biased by spring 20 and moved by screw 22. It will be appreciated that a similar movement means is provided to move optical fiber 12 in and out of the plane of the paper. In this manner, the laser beam is coupled to the fiber optic cable.
Figure 2 shows another apparatus by which such coupling can be obtained. In this apparatus, frame 18A includes receptacle 24 for receiving plug-in connector 26 on the end of optical fiber cable 12. Threaded collar 28 retains connector 26 in receptacle 24. Lens 1 4A is mounted on plate 30 that can be pivoted, as shown by the arrows, to place the center of laser beam 10 on the axis of optical fiber 13. Screws 32 and 34, one of which may be spring-loaded accomplish the desired pivotal movement, as well as the positioning of the end of optical fiber 13 at the focal point of lens 14.
As noted above, the above techniques are mechanically complex and lack repeatability, stability, and high resolution of adjustment.
Figure 3 shows the improved apparatus of the present invention. The apparatus is contained in housing 18B. A plate 36 of transparent material is placed in the path of laser beam 10 between lens 14B and the end of optical fiber 13. For explanatory purposes, plate 36 will be described herein as formed of transparent glass.
Plate 36 may be disc-like in form and is referred to as a disc below. Glass disc 36 has parallel faces through which the laser beam enters and exits. Means are provided in housing 18B to tilt glass disc 36 so that it can shifted out of the position perpendicular to the axis of beam 10 shown in Figure 3, to one in which it lies at some angle other than 90" two the axis of the beam. For this purpose, disc 36 may be mounted on plate 38 as by glueing disc 36 to plate 38. Plate 38 has an opening 40 along the axis of laser beam 10. It also has a generally hemispherical bulge 42 that coacts with the end of receptacle 24 to allow plate 38 and glass disc 36 to tilt. Plate 38 may be gimballed in an appropriate manner in housing 18B for this purpose. Plate 38 is biased by spring 44 and tilted by screw 46 in the plane of the drawing of Figure 3.It will be appreciated that a second screw 46 is provided to permit plate 38 to tilt in a plane normal to the plane of the paper of Figure 3, as shown in Figure 6.
In operation, laser beam 10 in the form of a converging cone from lens 14B passes through glass disc 36 positioned between lens 1 4B and the end of optical fiber 13. As the laser beam passes from the air through the glass of disc 36 back to the air, the portion of the conical beam striking disc 36 at an angle other than 90 will undergo refraction. Refraction is an angular displacement of the laser beam brought about by the different velocity of the laser beam in the glass than in the air on either side of it.
Assume disc 36 is oriented perpendicular to the axis of lase beam 10, as shown in Figure 3. Under these conditions, the laser beam 10 will not be displaced from its axis. However, the focal point of lens 14B and the beam waist of focused laser beam 10 is moved further from lens 1 4B due to the refraction occurring in glass disc36. By repositioning lens 14B with lens holder 48 threaded in housing 18B the focal point of lens 14B and the beam waist of laser beam 10 may be returned to the end of optical fiber 13.
By tilting glass disc 36 out of the perpendicular position shown in Figure 3, it is possible to obtain a displacement of the laser beam 10 exiting from the disc with respect to the laser beam applied to the disc through the refraction occurring in the glass disc 36. This displacement can be used to center the beam waist of focused laser beam 10 on the axis of optical fiber 13.
The displacement between the applied and exiting laser beas occurring upon the tilting of glass disc 36 is shown diagrammatically in Figure 4. The amount of displacemnt obtained is quantitatively shown in Figure 5. For simplicity only the axis of laser beam 10 is shown in Figure 5.
The amount of displacement is expressed by the formula
D=Tsin 1- Ncos$ N'cosy where:
d = amount of displacement of the axis of the exit laser beam 10 over that of the applied laser beam
T = thickness of glass disc 36 = = angle between the axis of applied laser beam 10 in air and a perpendicular to the face of glass disc 36, commonly termed the angle of incidence = = angle between the axis of laser beam 10 in glass disc 36 and a perpendicular to the face of glass disc 36, commonly termed the angle of refraction
N = index of refraction for air
N' = index of refraction for glass of disc 36
As shown in Figures 4 and 5, by tilting glass disc 36, the beam waist of laser beam 10 may be moved so that it can be applied to the axis of optical fiber 13.As will be noted from the above equation, the amount of displacement "d" is directly proportional to the thickness "T" of glas disc 36. By making the thickness of glass disc 36 small, the amount of displacement for a given amount of tilting of glass disc 36 may be made small so as to provide for very fine adjustment of the amount of displacement and high resolution to the coupling device of the present invention. That is, as large number of turns must be provided to screw 46 to obtain a small displacement of the laser beam 10. Very precise adjustments of the position of the laser beam can thus be obtained.
After the axis of laser beam 10 has been placed on the axis of optical fiber 13 by tilting glass disc 36, the position of the focal point of lens 14B with respect to the end of optical fiber 13 along the axis of laser beam 10 may be adjusted by threaded barrel 48 to place the focal point and beam waist on the exposed end of optical fiber 13 in cable 12. A high efficiency coupling between laser beam 10 and optical fiber 13 is thus obtained.
While the coupling device of the present invention has been described above, as applying laser beam 10 to optical fiber 13 in cable 12, it will be appreciated that the device may be utilized in the instance in which a laser beam is emerging from optical fiber 13 and is to be applied to lens 14. Also, while the light source has been described as a laser, it will be appreciated that other sources, such as an arc lamp may be used with the present invention.
It will also be appreciated that glass disc 36 may be used without lens 1 4B in the instance in which laser beam 10 is appropriately sized by other means for application to the exposed end of optical fiber 13.
It is preferable that glass disc 36 may be formed of optical grade glass with ground surfaces for receiving and emitting the light. While disc 36 has been described as made from glass in the above explanation, it will be appreciated that it may be made from other suitable materials, such as quartz, or from plastic, such as acrylic.
Claims (8)
1. A coupling device for use between a light beam and the end of an optical fiber and comprising a transparent means capable of refracting the light beam, placed along the path of the light beam exterior to the optical fiber and through which the light beam passes, the transparent means being spaced from the end of the optical fiber and means for tilting the transparent means out of a position normal to the path of the light beam for altering the position of the light beam with respect to the end of the optical fiber as a result of the refraction occurring in the transparent means as the light beam passes therethrough.
2. A device according to claim 1, wherein the transparent means is formed of glass.
3. A device according to claim 1 or claim 2 wherein the transparent means has parallel, light emitting and receiving faces, the distance between which controls the amount of displacement of the light beam for a given amount of tilt.
4. A coupling device according to any one of the preceding claims and including a lens spaced from the transparent means on the side opposite that facing the optical fiber, the lens being positioned along the path of the light beam for applying the light beam to the transparent means.
5. A coupling device according to claim 4 wherein the lens is a positive focal length lens.
6. A coupling device according to claim 4 or claim 5 further including means for adjusting the position of the lens along the path of the light beam.
7. A coupling device for coupling a laser beam to an ooptical fiber having an established cone of acceptance by centering the laser beam converging at an angle less than that of the cone of acceptance on the end of the fiber. the device comprising a positive focal length lens positioned along the path of the laser beam and spaced from the end of the optical fiber, the lens converging the laser beam at an angle less than that of the cone of acceptance of the optical fiber, and being positioned to place the focal point of the lens on the end of the optical fiber, a transparent means capable of refracting the laser beam placed along the path of the laser beam between the lens and the end of the optical fiber and means for tilting the transparent means to center the laser beam on the end of the optical fiber.
8. A coupling device according to claim 7 further including means for adjusting the position of the lens along the path of the laser beam for adjusting the placement of the focal point of the lens.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60943384A | 1984-05-11 | 1984-05-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8510894D0 GB8510894D0 (en) | 1985-06-05 |
| GB2158605A true GB2158605A (en) | 1985-11-13 |
Family
ID=24440782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08510894A Withdrawn GB2158605A (en) | 1984-05-11 | 1985-04-30 | Optical fiber coupling device |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6111711A (en) |
| GB (1) | GB2158605A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0389771A2 (en) * | 1989-03-27 | 1990-10-03 | Yuji Ikeda | Optical equipment of fiber laser Doppler velocimeter |
| US5016965A (en) * | 1987-10-08 | 1991-05-21 | British Telecommunications Public Limited Company | Optical package |
| WO1997010526A2 (en) * | 1995-09-11 | 1997-03-20 | Siemens Aktiengesellschaft | Device for adjusting a component for optical signal transmission |
| US5638472A (en) * | 1993-04-01 | 1997-06-10 | Optics For Research | Optical fiber and lens assembly having a movable lens and a fixed optical fiber |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB923569A (en) * | 1959-04-10 | 1963-04-10 | Franklin Inst Of The State Of | Optical image transmission systems |
| GB2009959A (en) * | 1977-11-21 | 1979-06-20 | American Optical Corp | Fibrescope dynamic image enhancement |
| GB2013924A (en) * | 1978-02-01 | 1979-08-15 | American Optical Corp | Dynamic image enhancer for fibrescopes |
| GB2081923A (en) * | 1980-08-15 | 1982-02-24 | American Optical Corp | Dynamic image enhancer for fibrescopes |
| EP0067761A2 (en) * | 1981-06-05 | 1982-12-22 | Instruments S.A. | Device for switching between optical fibres |
| GB2111716A (en) * | 1981-12-14 | 1983-07-06 | Elven Precision Limited | Improvements in or relating to optical scanning and optical image transmission |
| EP0115765A1 (en) * | 1983-01-07 | 1984-08-15 | Alcatel Cit | Commutation switch for an optical waveguide circuit |
-
1985
- 1985-04-30 GB GB08510894A patent/GB2158605A/en not_active Withdrawn
- 1985-05-10 JP JP9944885A patent/JPS6111711A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB923569A (en) * | 1959-04-10 | 1963-04-10 | Franklin Inst Of The State Of | Optical image transmission systems |
| GB2009959A (en) * | 1977-11-21 | 1979-06-20 | American Optical Corp | Fibrescope dynamic image enhancement |
| GB2013924A (en) * | 1978-02-01 | 1979-08-15 | American Optical Corp | Dynamic image enhancer for fibrescopes |
| GB2081923A (en) * | 1980-08-15 | 1982-02-24 | American Optical Corp | Dynamic image enhancer for fibrescopes |
| EP0067761A2 (en) * | 1981-06-05 | 1982-12-22 | Instruments S.A. | Device for switching between optical fibres |
| GB2111716A (en) * | 1981-12-14 | 1983-07-06 | Elven Precision Limited | Improvements in or relating to optical scanning and optical image transmission |
| EP0115765A1 (en) * | 1983-01-07 | 1984-08-15 | Alcatel Cit | Commutation switch for an optical waveguide circuit |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5016965A (en) * | 1987-10-08 | 1991-05-21 | British Telecommunications Public Limited Company | Optical package |
| EP0389771A2 (en) * | 1989-03-27 | 1990-10-03 | Yuji Ikeda | Optical equipment of fiber laser Doppler velocimeter |
| EP0389771A3 (en) * | 1989-03-27 | 1992-07-08 | Yuji Ikeda | Optical equipment of fiber laser doppler velocimeter |
| US5638472A (en) * | 1993-04-01 | 1997-06-10 | Optics For Research | Optical fiber and lens assembly having a movable lens and a fixed optical fiber |
| WO1997010526A2 (en) * | 1995-09-11 | 1997-03-20 | Siemens Aktiengesellschaft | Device for adjusting a component for optical signal transmission |
| WO1997010526A3 (en) * | 1995-09-11 | 1997-04-10 | Siemens Ag | Device for adjusting a component for optical signal transmission |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8510894D0 (en) | 1985-06-05 |
| JPS6111711A (en) | 1986-01-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0006662B1 (en) | Detachable connector for optical fibres | |
| US5500911A (en) | Lensed optical fiber assembly and process for alignment with an active device | |
| EP0115686B1 (en) | Optical alignment means | |
| US4737006A (en) | Optical fiber termination including pure silica lens and method of making same | |
| US4451115A (en) | Detachable coupling for optical fibres | |
| US4868361A (en) | Coupling device for high power laser beam transmitting optical fibers | |
| EP0350793B1 (en) | Variable ratio beam splitter and beam launcher | |
| CA1269267A (en) | Two lens optical package and method of making same | |
| EP0307487A1 (en) | Collimator lens for optical fiber | |
| US20030165292A1 (en) | Beam altering fiber lens device and method of manufacture | |
| US3912364A (en) | Mixer for optical waveguide bundle | |
| EP0119727B1 (en) | Optical connectors | |
| US5040862A (en) | Method of trimming optical power | |
| CN100529816C (en) | Focusing fiber optic | |
| GB1587158A (en) | Optical-fibre connector | |
| US4722582A (en) | Optical-fibre coupler | |
| EP0155379A3 (en) | Arrangement for coupling a light wave guide to a semiconductor laser and method for manufacturing such an arrangement | |
| CA1196795A (en) | Apparatus and methods for testing lens structure | |
| US5022733A (en) | Low-reflection ball lens connector part | |
| GB2158605A (en) | Optical fiber coupling device | |
| CN212905744U (en) | Laser coupling to single mode fiber angle deviation adjusting module applied to automatic machine | |
| US6718090B2 (en) | Automatic device for assembling fiber collimator | |
| Koga et al. | Development of a portable laser sheet | |
| CN2284406Y (en) | Optical fibre coupling detector | |
| JPS6049283B2 (en) | Optical transmission lens terminal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |