GB2153515A - Illuminator utilising a solid light guide - Google Patents

Illuminator utilising a solid light guide Download PDF

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Publication number
GB2153515A
GB2153515A GB08402130A GB8402130A GB2153515A GB 2153515 A GB2153515 A GB 2153515A GB 08402130 A GB08402130 A GB 08402130A GB 8402130 A GB8402130 A GB 8402130A GB 2153515 A GB2153515 A GB 2153515A
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GB
United Kingdom
Prior art keywords
guide
light
illuminator
patch
diffusing material
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
GB08402130A
Other versions
GB2153515B (en
GB8402130D0 (en
Inventor
Michael Anthony Vann
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to GB08402130A priority Critical patent/GB2153515B/en
Publication of GB8402130D0 publication Critical patent/GB8402130D0/en
Publication of GB2153515A publication Critical patent/GB2153515A/en
Application granted granted Critical
Publication of GB2153515B publication Critical patent/GB2153515B/en
Expired legal-status Critical Current

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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
    • G02B6/4298—Coupling light guides with opto-electronic elements coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
    • 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
    • G02B6/001—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 the light being emitted along at least a portion of the lateral surface of the fibre

Abstract

An illuminator comprises a solid light guide 1, atone end of which is applied a patch of white diffusing material 5. Light incident on the other end of the guide is transmitted by total internal reflection to the aforesaid patch, at which point it is scattered and emerges from the sidewall of the guide to form a bright, uniform source of light. <IMAGE>

Description

SPECIFICATION Illuminator utilising a solid light guide This invention relates to an illuminator in which light is transmitted along a solid transparent guide.
The use of fibre optic bundles and solid cylindrical light guides is well known as a means of transmitting light from a source to an object with high efficiency. Such optical arrangements are in wide use to produce localised high intensity illumination for visual inspection purposes and for photographic or electronic imaging applications. However, it is difficult with existing techniques to achieve good uniformity of illumination without resort to the use of diffusers which involve a considerable loss of intensity. Uniformity is of particular importance in applications of electronic imaging systems to the measurement or inspection of small components where it is necessary to back-illuminate the object with a spatially uniform source of light such that the profile of the object may be well defined and of good contrast.At the same time it is frequently required that this source of light be of considerable intensity, as for example when using solid-state imaging systems running at very high speed.
Accordingly, in the present invention there is provided an illuminator comprising a solid transparent cylindrical light guide in which light is incident at one end and is transmitted down the guide by total internal reflection until it encounters a white diffusing material applied to part of the outside cylindrical surface of the guide, adjacent to the other end. At this point, total internal reflection is frustrated and the light is scattered in all directions. A large proportion of this light is transmitted out of the side of the guide, and if the patch of diffusing material is viewed through the guide in a direction perpendicular to its length, it forms the bright uniform source that is the object of the invention.
The uniformity of the luminous area is controlled by the following variables: (a) The aspect ratio of the guide (ratio of iength to diameter).
(b) The proportion of the surface round which the diffusing material is applied.
(c) The numerical aperture of the incident light beam at the input end.
(d) The proximity of the diffusing patch to the end of the guide.
(e) The scattering properties of the end face of the guide which is adjacent to the diffusing patch.
An illuminator of the type described above is not restricted to operate with visible light only. It may be used with ultra-violet or infrared radiation of any wavelengths which are transmitted by the guide.
A specific example will now be described, which embodies the main features of the invention. Referring to the accompanying drawing, the illuminator comprises a solid cylindrical light guide 1, to the end of which is applied an area of white diffusing material 5, which may be sprayed on in the form of a white paint. The end of the guide adjacent to this patch is ground to form a diffusing surface, on part of which the diffusing material may also be applied.
The opposite end of the guide is ground and polished flat to be highly transparent. A light source 2, in the form of a low-voltage compact filament tungsten-halogen lamp with integral reflector, focuses a bright patch of light on the polished end of the guide, said light being then transmitted down the guide by total internal reflection. To reduce the size of the light patch such that it falls within the confines of the guide end-face, an additional aspherical lens 3 is situated between the lamp and the guide. A transparent infra-red absorbing filter 4 is placed between the lens and the guide to minimise the heating effect of the incident radiation.
Items 2, 3 and 4 are contained in a metal housing (not shown) which is attached to the end of the guide.
1. An illuminator comprising a solid transparent cylindrical light guide, in wich light is incident at one end and is transmitted down the guide by total internal reflection until it encounters a white diffusing material applied to part of the external cylindrical surface of the guide adjacent to the other end, whereupon the total internal reflection is frustrated and the light is scattered in all directions, the major portion of said light emerging from the side wall of the guide opposite to the diffusing patch, such that said patch now forms a bright and uniformly luminous area.
2. An illuminator as claimed in Claim 1 in which the source of light comprises a low-voltage compact filament tungsten-halogen lamp with integral reflector.
3. An illuminator as claimed in Claim 2 wherein an additional focusing lens is placed between the lamp and the light guide.
4. An illuminator as claimed in any preceding claim wherein a transparent infrared-absorbing filter is placed adjacent to the input end of the light guide.
5. An illuminator as claimed in any preceding claim wherein the light guide is not straight but may have one or more bends.
6. An illuminator as claimed in any preceding claim, in which the light guide is not of constant diameter, but may reduce in diameter gradually towards the end remote from the light source.
7. An illuminator as claimed in any preceding claim, in which the diffusing material is of a colour other than white.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Illuminator utilising a solid light guide This invention relates to an illuminator in which light is transmitted along a solid transparent guide. The use of fibre optic bundles and solid cylindrical light guides is well known as a means of transmitting light from a source to an object with high efficiency. Such optical arrangements are in wide use to produce localised high intensity illumination for visual inspection purposes and for photographic or electronic imaging applications. However, it is difficult with existing techniques to achieve good uniformity of illumination without resort to the use of diffusers which involve a considerable loss of intensity. Uniformity is of particular importance in applications of electronic imaging systems to the measurement or inspection of small components where it is necessary to back-illuminate the object with a spatially uniform source of light such that the profile of the object may be well defined and of good contrast.At the same time it is frequently required that this source of light be of considerable intensity, as for example when using solid-state imaging systems running at very high speed. Accordingly, in the present invention there is provided an illuminator comprising a solid transparent cylindrical light guide in which light is incident at one end and is transmitted down the guide by total internal reflection until it encounters a white diffusing material applied to part of the outside cylindrical surface of the guide, adjacent to the other end. At this point, total internal reflection is frustrated and the light is scattered in all directions. A large proportion of this light is transmitted out of the side of the guide, and if the patch of diffusing material is viewed through the guide in a direction perpendicular to its length, it forms the bright uniform source that is the object of the invention. The uniformity of the luminous area is controlled by the following variables: (a) The aspect ratio of the guide (ratio of iength to diameter). (b) The proportion of the surface round which the diffusing material is applied. (c) The numerical aperture of the incident light beam at the input end. (d) The proximity of the diffusing patch to the end of the guide. (e) The scattering properties of the end face of the guide which is adjacent to the diffusing patch. An illuminator of the type described above is not restricted to operate with visible light only. It may be used with ultra-violet or infrared radiation of any wavelengths which are transmitted by the guide. A specific example will now be described, which embodies the main features of the invention. Referring to the accompanying drawing, the illuminator comprises a solid cylindrical light guide 1, to the end of which is applied an area of white diffusing material 5, which may be sprayed on in the form of a white paint. The end of the guide adjacent to this patch is ground to form a diffusing surface, on part of which the diffusing material may also be applied. The opposite end of the guide is ground and polished flat to be highly transparent. A light source 2, in the form of a low-voltage compact filament tungsten-halogen lamp with integral reflector, focuses a bright patch of light on the polished end of the guide, said light being then transmitted down the guide by total internal reflection. To reduce the size of the light patch such that it falls within the confines of the guide end-face, an additional aspherical lens 3 is situated between the lamp and the guide. A transparent infra-red absorbing filter 4 is placed between the lens and the guide to minimise the heating effect of the incident radiation. Items 2, 3 and 4 are contained in a metal housing (not shown) which is attached to the end of the guide. CLAIMS
1. An illuminator comprising a solid transparent cylindrical light guide, in wich light is incident at one end and is transmitted down the guide by total internal reflection until it encounters a white diffusing material applied to part of the external cylindrical surface of the guide adjacent to the other end, whereupon the total internal reflection is frustrated and the light is scattered in all directions, the major portion of said light emerging from the side wall of the guide opposite to the diffusing patch, such that said patch now forms a bright and uniformly luminous area.
2. An illuminator as claimed in Claim 1 in which the source of light comprises a low-voltage compact filament tungsten-halogen lamp with integral reflector.
3. An illuminator as claimed in Claim 2 wherein an additional focusing lens is placed between the lamp and the light guide.
4. An illuminator as claimed in any preceding claim wherein a transparent infrared-absorbing filter is placed adjacent to the input end of the light guide.
5. An illuminator as claimed in any preceding claim wherein the light guide is not straight but may have one or more bends.
6. An illuminator as claimed in any preceding claim, in which the light guide is not of constant diameter, but may reduce in diameter gradually towards the end remote from the light source.
7. An illuminator as claimed in any preceding claim, in which the diffusing material is of a colour other than white.
GB08402130A 1984-01-27 1984-01-27 Illuminator utilising a solid light guide Expired GB2153515B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08402130A GB2153515B (en) 1984-01-27 1984-01-27 Illuminator utilising a solid light guide

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08402130A GB2153515B (en) 1984-01-27 1984-01-27 Illuminator utilising a solid light guide

Publications (3)

Publication Number Publication Date
GB8402130D0 GB8402130D0 (en) 1984-02-29
GB2153515A true GB2153515A (en) 1985-08-21
GB2153515B GB2153515B (en) 1987-12-09

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08402130A Expired GB2153515B (en) 1984-01-27 1984-01-27 Illuminator utilising a solid light guide

Country Status (1)

Country Link
GB (1) GB2153515B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2184220A (en) * 1984-09-27 1987-06-17 Gary J Thompson Decorative light display
EP0800036A1 (en) * 1996-04-04 1997-10-08 Hitachi Cable, Ltd. Lighting system
WO1997048946A1 (en) * 1996-06-17 1997-12-24 Sky Solutions Limited Optical conduit for transmitting and releasing luminescent radiation
US8167434B2 (en) 2006-12-21 2012-05-01 Koninklijke Philips Electronics N.V. Light projection system and display device
US20140328081A1 (en) * 2013-05-02 2014-11-06 Hon Hai Precision Industry Co., Ltd. Light guide bar and light emitting device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2184220A (en) * 1984-09-27 1987-06-17 Gary J Thompson Decorative light display
GB2184220B (en) * 1984-09-27 1990-09-19 Gary J Thompson Decorative lighting devices
EP0800036A1 (en) * 1996-04-04 1997-10-08 Hitachi Cable, Ltd. Lighting system
US5857761A (en) * 1996-04-04 1999-01-12 Hitachi Cable, Ltd. Illumination device
WO1997048946A1 (en) * 1996-06-17 1997-12-24 Sky Solutions Limited Optical conduit for transmitting and releasing luminescent radiation
US6272265B1 (en) 1996-06-17 2001-08-07 Sky Solutions Limited Lighting system for transmitting and releasing luminescent radiation
US8167434B2 (en) 2006-12-21 2012-05-01 Koninklijke Philips Electronics N.V. Light projection system and display device
US20140328081A1 (en) * 2013-05-02 2014-11-06 Hon Hai Precision Industry Co., Ltd. Light guide bar and light emitting device
US9250375B2 (en) * 2013-05-02 2016-02-02 Hon Hai Precision Industry Co., Ltd. Light guide bar and light emitting device

Also Published As

Publication number Publication date
GB2153515B (en) 1987-12-09
GB8402130D0 (en) 1984-02-29

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930127