GB2269911A - Splayed optical fibre bundle-light source connector - Google Patents

Splayed optical fibre bundle-light source connector Download PDF

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Publication number
GB2269911A
GB2269911A GB9217447A GB9217447A GB2269911A GB 2269911 A GB2269911 A GB 2269911A GB 9217447 A GB9217447 A GB 9217447A GB 9217447 A GB9217447 A GB 9217447A GB 2269911 A GB2269911 A GB 2269911A
Authority
GB
United Kingdom
Prior art keywords
light guide
light
light source
fibres
optical axis
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.)
Granted
Application number
GB9217447A
Other versions
GB2269911B (en
GB9217447D0 (en
Inventor
Philip Michael Coath
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Keymed Medical and Industrial Equipment Ltd
Original Assignee
Keymed Medical and Industrial Equipment Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Keymed Medical and Industrial Equipment Ltd filed Critical Keymed Medical and Industrial Equipment Ltd
Priority to GB9217447A priority Critical patent/GB2269911B/en
Publication of GB9217447D0 publication Critical patent/GB9217447D0/en
Publication of GB2269911A publication Critical patent/GB2269911A/en
Application granted granted Critical
Publication of GB2269911B publication Critical patent/GB2269911B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/00112—Connection or coupling means
    • A61B1/00117—Optical cables in or with an endoscope
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/06—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements
    • A61B1/07—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements using light-conductive means, e.g. optical fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
    • G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
    • G02B23/2407—Optical details
    • G02B23/2461—Illumination
    • G02B23/2469—Illumination using optical fibres
    • 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
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
    • G02B6/0006—Coupling light into the fibre
    • 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
    • G02B6/04—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres
    • 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
    • G02B6/4298—Coupling light guides with opto-electronic elements coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/00112—Connection or coupling means
    • A61B1/00121—Connectors, fasteners and adapters, e.g. on the endoscope handle
    • A61B1/00126—Connectors, fasteners and adapters, e.g. on the endoscope handle optical, e.g. for light supply cables
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/06—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements
    • A61B1/0661—Endoscope light sources
    • A61B1/0669—Endoscope light sources at proximal end of an endoscope

Abstract

A light guide 1 for a borescope or endoscope has an optical fibre bundle 6 terminating in a light source connector 3. The light source may have a lamp 26 and reflector 27 in axial alignment with the connector and providing a convergent light beam with maximum intensity in a non-axial direction. The connector is provided with a terminal assembly 16 in which end portions 15 of the fibres are splayed so as to lie within an annular space 14 in which they are constrained to lie at a predetermined angle relative to the axis. <IMAGE>

Description

A LIGHT GUIDE This invention relates to a light guide for a borescope or endoscope.
It is known to provide a light guide comprising a bundle of optical fibres extending integrally between a proximal end presented to a light source and a distal end from which light is emergent to illuminate the field of view of the borescope or endoscope. The proximal end is provided with a connector received in a light source having a lamp and a reflector for collecting and focusing light from the lamp on to an end face of the bundle.
A problem with such light sources is that, because the lamp is typically axially located intermediate the reflector and the end face of the bundle, the presence of the lamp tends to disrupt the transmission of axially propagated light. Consequently the intensity of the light received at the end face varies as a function of angle relative to the optical axis such that the intensity of light incident at an acute angle to the optical axis is greater than the intensity of light travelling parallel to the optical axis.
The optical fibres within the.bundle tend to preserve this angular variation of intensity of the transmitted light so that light emerging from the distal end face tends to illuminate the object field more brightly at a peripheral annulus surrounding a central region which is noticeably less well illuminated.
This is particularly disadvantageous when using a borescope with a narrow field of view, typically 1001.since illumination of the object field is concentrated outside of the field of view of the borescope. In some instances the intensity within the field of view may even include a central dark patch which significantly degrades the performance of the borescope or endoscope.
According to the present invention there is disclosed a light guide for an optical instrument such as a borescope or endoscope comprising a bundle of optical fibres extending integrally between a proximal end having a light source connector and a distal end having a distal end face through which light from the light source is emergent in use to illuminate the field of view of the instrument, the light source connector being co-operable with a light source providing in use a beam of light convergent about an optical axis, the connector comprising a terminal assembly in which a first portion of the bundle extends co-axially with the optical axis and a proximal end portion is splayed such that end portions of the fibres lie within an annular space defined between inner and outer conically tapered surfaces, the end portions of the fibres thereby being constrained to extend at respective angles substantially equal in magnitude to a preferred angle relative to the optical axis, and wherein the end portions of the fibres terminate in an annular end face upon which the convergent light beam is incident in use.
An advantage of such a light guide is that the formation of a central dark patch in the illuminated field of view is avoided and more efficient use is made of the available light from the light source.
Preferably the terminal assembly comprises a tubular projection defining a cylindrical conduit merging with a conically tapering internal surface which defines the outer tapered surface of the annular space and wherein an insert is received coaxially within the tubular projection, the insert having a conically tapering surface constituting the inner tapered surface of the annular space.
Such an arrangement provides a convenient means of defining the annular space. A further advantage is that, compared with the prior arrangement of the fibres being bonded into a cylindrical mass, the formation of the end portions into an annular mass results in a greater external area being available for contact with the surrounding material of the connector and this enhances the conduction of heat away from the bundle. Heat is dissipated in the end portions of the fibres due to the great intensity of the convergent light being incident on the end face and it has hitherto been necessary to use adhesives for bonding the fibres which are capable of withstanding high temperatures. The annular arrangement of the present invention provides for a lower operating temperature of the end portions of the fibres so that an adhesive with a lower operating temperature can be used.
Typically the high temperature adhesives have a much longer curing time than low temperature adhesives so that a further advantage of the present invention is that the terminal assembly can be more rapidly manufactured since adhesives with a lower cure time can be utilised.
Preferably the insert further comprises a cylindrical projection extending distally into the tubular projection.
The cylindrical projection is useful in locating the insert within the fibre bundle during assembly.
Preferably the insert comprises at least one circumferential groove and the conically tapering internal surface of the tubular projection may similarly be provided with at least one circumferential groove.
These grooves provide a key for adhesive to form a satisfactory bond between the surfaces and the end portions of the fibres.
The conically tapered surface may typically be inclined at an angle relative to the optical axis of between 50 and 100.
Conveniently the annular end face is substantially perpendicular to the optical axis.
According to a further aspect of the present invention there is disclosed optical apparatus comprising a light guide as disclosed above in combination with a light source comprising a lamp and a reflector wherein the lamp is located axially intermediate the reflector and the terminal assembly.
A preferred embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawing of which: Figure 1 is a part sectional plan view of a light guide connector received within a light source.
In Figure 1 a light guide 1 has a proximal end portion 2 having a connector 3 which is shown received within a socket 4 of a light source 5.
The light guide 1 comprises an incoherent bundle 6 of optical fibres extending through a flexible tube 7 extending integrally from a borescope (not shown).
The bundle 6 extends through the connector 3 within which a first portion 8 of the bundle is loosely packed within a cylindrical conduit 9 defined by the connector 3.
The cylindrical conduit 9 extends within a tubular projection 10 of the connector which has a proximal end portion 11 within which the conduit 9 is flared to define a conically tapering internal surface 12.
A metallic insert 13 is received within the proximal end portion 11 and extends coaxially with the conduit 9 thereby defining an annular space 14 between the insert and the internal surface 12 which is occupied by tightly packed end portions 15 of the fibres constituting the bundle 6.
The end portions 15 are adhesively bonded together and to both the insert 13 and the tubular projection 10 thereby constituting a terminal assembly 16 having a polished end face 17 which includes an annular end face 18 of the end portions 15 of the fibres constituting the bundle 6.
The insert 13 has a conically tapering surface 19 which extends in parallel spaced relationship to the 0 internal surface 12 and at an angle of 7 to an optical axis 20 extending coaxially through the conduit 9. The insert 13 includes a cylindrical projection 21 which projects axially into the first portion 8 of the bundle 6.
The tapering surface 19 and the cylindrical projection 21 of the insert 13 are provided with a plurality of circumferential grooves 22 and 23 respectively acting as a key for adhesive bonding between the insert and the fibres of the bundle 6.
The internal surface 12 of the tubular projection 10 is similarly provided with internal circumferential grooves 24 for like purposes.
The end portions 15 of the fibres are constrained within the annular space 14 to extend at an angle of substantially 70 to the axis 20 and are uniformly circumferentially distributed around the annular space. The annular end face 18 extends at right angles to the axis 20 so that each end portion 15 terminates in an obliquely extending end face which is angled at or about 830 relative to the longitudinal extent of the end portion.
The proximal end portion 2 has a shoulder 25 which limits the depth of insertion of the connector 3 within socket 4 thereby accurately positioning the end face 17 relative to a fixed lamp 26 which is provided with a dichroic reflector 27 arranged to collect and focus light from the lamp symmetrically about the axis 20. The end face 17 is positioned so as to be slightly nearer to the lamp 26 than the focus position at which light from the reflector would be focused on the axis 20 so that a convergent light beam 28 is incident on the end face.
A movable shutter 29 is mounted on a pivot 30 and can be moved by a linkage 31 so as to selectively mask the end face to vary the amount of light transmitted.
In use the connector 3 is inserted into the socket 4 as shown in Figure 1 and with the shutter 29 in the open position light from the lamp 26 is reflected from reflector 27 so as to be incident on the end face 17. Light which is incident on the annular end face 18 of the fibres will be transmitted into the fibres provided the angle of incidence falls within the acceptance angle characterising the fibres.
The light will be conducted from the proximal end portion 2 to a distal end portion (not shown) from which it will emerge to illuminated an object field.
Light travelling substantially axially from the lamp or from the reflector so as to be incident upon the annular end face 18 will also be transmitted through the fibres. This light will however enter the end portions 15 of the fibres at an oblique angle due to the flared configuration of the fibre bundle within the terminal assembly and will consequently emerge from the distal end non-axially.
Axially emergent illumination at the distal end will be provided by rays which are incident on the annular end face 18 substantially in line with the longitudinal extent of the end portions 15 of the fibres. Such rays will arrive at the end face 18 by reflection from the reflector 27. Peak light intensity from the lamp and reflector is available at this angle of incidence on the end face thereby providing peak illumination axially at the distal end of the light guide 1.
The preferred angle defined by the configuration of the annular space 14 will depend upon the specific lamp utilised and the focal length of the reflector.
The optimum angle can be arrived at empirically.
Typically however the anle will be in the range to 100.
The light guide is assembled by inserting the fibre bundle into the tube 7 such that the end portions of the fibres project from the proximal end portion 11 of the connector 3. The insert 13 is then inserted centrally within the conically tapering internal surface 12 and the end portions of the fibre adjusted until a uniform annular layer extends around the insert.
Adhesive is then applied to the end portions of the fibres and is drawn by capilliary action into the interstices between the end portions of the fibres lying within the annular space 14. The insert and fibres are clamped during curing and the end face 17 is cut and polished ready for use.
During assembly the insert 13 may be provided with a proximally projecting handle to facilitate alignment and manipulation of the insert, the handle (not shown) being removed during the cutting and polishing operation.

Claims (10)

1. A light guide for an optical instrument such as a borescope or endoscope comprising a bundle of optical fibres extending integrally between a proximal end having a light source connector and a distal end having a distal end face through which light from the light source is emergent in use to illuminate the field of view of the instrument, the light source connector being co-operable with a light source providing in use a beam of light convergent about an optical axis, the connector comprising a terminal assembly in which a first portion of the bundle extends co-axially with the optical axis and a proximal end portion is splayed such that end portions of the fibres lie within an annular space defined between inner and outer conically tapered surfaces, the end portions of the fibres thereby being constrained to extend at respective angles substantially equal in magnitude to a preferred angle relative to the optical axis, and wherein the end portions of the fibres terminate in an annular end face upon which the convergent light beam is incident in use.
2. A light guide as claimed in Claim 1, wherein the terminal assembly comprises a tubular projection defining a cylindrical conduit merging with a conically tapering internal surface which defines the outer tapered surface of the annular space and wherein an insert is received coaxially within the tubular projection, the insert having a conically tapering surface constituting the inner tapered surface of the annular space.
3. A light guide as claimed in Claim 2, wherein the insert further comprises a cylindrical projection extending distally into the tubular projection.
4. A light guide as claimed in any of Claims 2 and 3, wherein the insert further comprises at least one circumferential groove.
5. A light guide as claimed in any of Claims 2 to 4, wherein the conically tapering internal surface of the tubular projection is provided with at least one circumferential groove.
6. A light guide as claimed in any preceding claim, wherein the conically tapered surfaces are inclined at an angle relative to the optical axis of between 50 and 100.
7. A light guide as claimed in any preceding claim, wherein the annular end face is substantially perpendicular to the optical axis.
8. Optical apparatus comprising a light guide as claimed in any preceding claim in combination with a light source comprising a lamp and a reflector wherein the lamp is located axially intermediate the reflector and the terminal assembly.
9. A light guide substantially as hereinbefore disclosed with reference to and as shown in the accompanying drawing.
10. Optical apparatus substantially as hereinbefore disclosed with reference to and as shown in the accompanying drawing.
GB9217447A 1992-08-17 1992-08-17 Light source connector with splayed optical fibre bundle Expired - Lifetime GB2269911B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9217447A GB2269911B (en) 1992-08-17 1992-08-17 Light source connector with splayed optical fibre bundle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9217447A GB2269911B (en) 1992-08-17 1992-08-17 Light source connector with splayed optical fibre bundle

Publications (3)

Publication Number Publication Date
GB9217447D0 GB9217447D0 (en) 1992-09-30
GB2269911A true GB2269911A (en) 1994-02-23
GB2269911B GB2269911B (en) 1996-03-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9217447A Expired - Lifetime GB2269911B (en) 1992-08-17 1992-08-17 Light source connector with splayed optical fibre bundle

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0675319A1 (en) * 1994-03-30 1995-10-04 Ford Motor Company Light distribution system
EP0675377A2 (en) * 1994-03-30 1995-10-04 Ford Motor Company A light collector
GB2298055A (en) * 1995-02-14 1996-08-21 Eurotec Fibre Optics Ltd Light box on mount having aperture for optical cable
WO1999053240A1 (en) * 1998-04-15 1999-10-21 Minnesota Mining And Manufacturing Company Mounting assembly for a light conduit lighting system
US6398421B1 (en) 1998-04-15 2002-06-04 3M Innovative Properties Company Coupling system for a light conduit

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4580552A (en) * 1981-11-19 1986-04-08 Olympus Optical Co., Ltd. Illuminating optical system for endoscopes
US4768858A (en) * 1985-07-08 1988-09-06 Trimedyne, Inc. Hollow fiberoptic

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4580552A (en) * 1981-11-19 1986-04-08 Olympus Optical Co., Ltd. Illuminating optical system for endoscopes
US4768858A (en) * 1985-07-08 1988-09-06 Trimedyne, Inc. Hollow fiberoptic

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0675319A1 (en) * 1994-03-30 1995-10-04 Ford Motor Company Light distribution system
EP0675377A2 (en) * 1994-03-30 1995-10-04 Ford Motor Company A light collector
EP0675377A3 (en) * 1994-03-30 1996-04-24 Ford Motor Co A light collector.
GB2298055A (en) * 1995-02-14 1996-08-21 Eurotec Fibre Optics Ltd Light box on mount having aperture for optical cable
GB2298055B (en) * 1995-02-14 1999-09-15 Eurotec Fibre Optics Ltd Improvements relating to light transmission means
WO1999053240A1 (en) * 1998-04-15 1999-10-21 Minnesota Mining And Manufacturing Company Mounting assembly for a light conduit lighting system
US6152578A (en) * 1998-04-15 2000-11-28 3M Innovative Properties Company Mounting assembly for a light conduit lighting system
US6398421B1 (en) 1998-04-15 2002-06-04 3M Innovative Properties Company Coupling system for a light conduit

Also Published As

Publication number Publication date
GB2269911B (en) 1996-03-20
GB9217447D0 (en) 1992-09-30

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Date Code Title Description
PE20 Patent expired after termination of 20 years

Expiry date: 20120816