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GB2188143A - Improvements relating to optical position sensing arrangements - Google Patents
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GB2188143A - Improvements relating to optical position sensing arrangements - Google Patents

Improvements relating to optical position sensing arrangements Download PDF

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Publication number
GB2188143A
GB2188143A GB08606550A GB8606550A GB2188143A GB 2188143 A GB2188143 A GB 2188143A GB 08606550 A GB08606550 A GB 08606550A GB 8606550 A GB8606550 A GB 8606550A GB 2188143 A GB2188143 A GB 2188143A
Authority
GB
United Kingdom
Prior art keywords
fibre
zone plate
light
optical
wavelength
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
GB08606550A
Other versions
GB2188143B (en
GB8606550D0 (en
Inventor
John Philip Dakin
Charles Robert Batchellor
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.)
GE Healthcare UK Ltd
Plessey Co Ltd
Original Assignee
GE Healthcare UK Ltd
Plessey Co 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 GE Healthcare UK Ltd, Plessey Co Ltd filed Critical GE Healthcare UK Ltd
Priority to GB8606550A priority Critical patent/GB2188143B/en
Publication of GB8606550D0 publication Critical patent/GB8606550D0/en
Priority to JP62501799A priority patent/JPS63502852A/en
Priority to PCT/GB1987/000182 priority patent/WO1987005689A1/en
Priority to EP19870901593 priority patent/EP0273918A1/en
Publication of GB2188143A publication Critical patent/GB2188143A/en
Application granted granted Critical
Publication of GB2188143B publication Critical patent/GB2188143B/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/28—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication
    • G01D5/30—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication the beams of light being detected by photocells

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

An optical fibre sensor or the remote measurement of linear position wherein white light is fed via an optical fibre to illuminate a zone plate from which it is reflected to travel back along a second fibre arranged parallel to the first fibre to a wavelength analyser in dependence upon which the indication of position is determined, characterised in that the arrangement includes a lens effective to focus the white lght from the first fibre onto the zone plate whereby angular mismatch loss is eliminated whilst still allowing the second fibre to be placed parallel with the optical axis.

Description

SPECIFICATION Improvements relating to optical position sensing arangements This invention relates to optical position sensing arrangements especially suitableforthe remote measurement of the relative position or linear displacement of moving bodies.
One known optical position sensing arrangement for remotely measuring the relative position or displacement of a body comprises a holographic zone plate which may be attached to the aforesaid body and a pair of optical fibres one of which carries from a remote light source white lightfor illuminating the holographic zone plate and the other of which having its end coterminous with that of the other fibre collects monochromatic light reflected from the zone plate and having a centre wavelength representative ofthe distance between the ends of the optical fibres and the zone plate. The collected light is conveyed by the optical fibre to a wavelength analyser which effectively provides an indication of the distance between the fibre ends and the zone plate.If this distance is varied then the wavelength of the collected lightwill vary and the change in distance or displacement of the plate relative to the fibre ends will be indicated bythewavelength analyser. This known arrangement suffers from the disadvantagethatthelightemergingfromthe optical fibre connected to the source of white light takes the form of a cone of semi-angle of which is determined by the fixed numerical aperture of the input fibre. Consequently, unless the zone plate is made sufficiently large some ofthe light emerging from the fibre will not impinge on the plate andwill therefore be wasted leading to overall optical inefficiency. The position could be alleviated by providing higher power white light sources and/or more sophisticated wavelength analysers.
According to the present invention the above mentioned disavantage is overcome by providing an optical position sensing arrangement comprising two optical fibres and a holographiczone plate, in which lens means is interposed between the co-terminous ends of said fibres, along one of which (i.e. light transmission fibre) white light is conveyed from a remote light source, and the zone plate, wherebyall ofthe light emerging from the end ofthe light transmission fibre is focused by said lens means so that it all impinges on the zone plate and in which the co-terminous end of the other fibre )i.e.
light collecting fibre) collects all the lightfrom the zone plate and conveys itto a wavelength analyser which indicates the wavelength of the collected light and thus the distance between the co-terminous ends of the optical fibres and the zone plate.
By way of example the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a known optical position sensing arrangement; and, Figure2 shows an optical position sensing arrangement according to the present invention.
Referring to Figure 1, light derived from a white light source 1 is conveyed by an optical fibre 2 (i.e.
Iighttransmission fibre) to a remote location where it is utilisedforthe illumination of a holographic zone plate 3 in spaced relationship with the light emerging end ofthe optical fibre 2. The zone plate may be attached to a linearly movable body (notshown) while the end of the lighttransmission fibre 2 be fixed. Monochromatic light reflected by the zone plate 3 is arranged to be collected by the optical fibre 4(i.e. lightcollectingfibre)whichconveysthe collected lightto a wavelength analyser 5.
The wavelength of the collected lightwhich will be determined by the analyser 5 will be dependent upon the distance L between the co-terminous ends ofthe fibres 2 and 4 and the zone plate 3. Anyvariation in this distance Twill cause a change in the wavelength ofthe collected monochromatic light which will be detected by the analyser 5 and provide an indication of the position or displacement of the zone plate 3 relative to the fixed end of the optical fibre 2.
As can be appreciated from Figure 1, some ofthe cone of light emerging from the optical fibre 2 may fail to impinge on the zone plate 3, more especially as the distance L increases. Consequently, the overall optical efficiency of the sensing arrangement is reduced necessitating, more powerful white light sources and/or more sophisticated wavelength analysers.
In accordance with the invention, the efficiency of such position sensing arrangements is improved, as depicted in Figure 2, by providing a lens 6which is interposed between the co-terminous ends ofthe light transmission and light collecting fibres 2 and 4 andthe holographiczone plate 3. In view ofthe smallerangleofthecone of light emerging fromthe lens 6 all, or substantially all, of the light emerging from the end of the light transmission fibre 2 effectively impinges on the zone plate 3.
1. An optical position sensing arrangement comprising two optical fibres and a holographic zone plate which are relatively movable, in which lens means is interposed between the co-terminous ends of said optical fibres, along one of which (i.e.
lighttransmission fibre) light is conveyed from a remote white light source, and the zone plate, whereby all ofthe light emerging from the end ofthe light transmission fibre is focused by the lens means on to the zone plate and in which the co-terminous end ofthe otheroptical fibre (i.e. light coliecting fibre) collects all of the light which is reflected from the zone plate and conveys itto a wavelength analyser for determining the wavelength of the collected light which is indicative of the distance between the zone plate and the co-terminous ends of the said one fibre.
2. An optical position sensing arrangement substantially as hereinbefore described with reference to Figure 2.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to optical position sensing arangements This invention relates to optical position sensing arrangements especially suitableforthe remote measurement of the relative position or linear displacement of moving bodies. One known optical position sensing arrangement for remotely measuring the relative position or displacement of a body comprises a holographic zone plate which may be attached to the aforesaid body and a pair of optical fibres one of which carries from a remote light source white lightfor illuminating the holographic zone plate and the other of which having its end coterminous with that of the other fibre collects monochromatic light reflected from the zone plate and having a centre wavelength representative ofthe distance between the ends of the optical fibres and the zone plate. The collected light is conveyed by the optical fibre to a wavelength analyser which effectively provides an indication of the distance between the fibre ends and the zone plate.If this distance is varied then the wavelength of the collected lightwill vary and the change in distance or displacement of the plate relative to the fibre ends will be indicated bythewavelength analyser. This known arrangement suffers from the disadvantagethatthelightemergingfromthe optical fibre connected to the source of white light takes the form of a cone of semi-angle of which is determined by the fixed numerical aperture of the input fibre. Consequently, unless the zone plate is made sufficiently large some ofthe light emerging from the fibre will not impinge on the plate andwill therefore be wasted leading to overall optical inefficiency. The position could be alleviated by providing higher power white light sources and/or more sophisticated wavelength analysers. According to the present invention the above mentioned disavantage is overcome by providing an optical position sensing arrangement comprising two optical fibres and a holographiczone plate, in which lens means is interposed between the co-terminous ends of said fibres, along one of which (i.e. light transmission fibre) white light is conveyed from a remote light source, and the zone plate, wherebyall ofthe light emerging from the end ofthe light transmission fibre is focused by said lens means so that it all impinges on the zone plate and in which the co-terminous end of the other fibre )i.e. light collecting fibre) collects all the lightfrom the zone plate and conveys itto a wavelength analyser which indicates the wavelength of the collected light and thus the distance between the co-terminous ends of the optical fibres and the zone plate. By way of example the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a known optical position sensing arrangement; and, Figure2 shows an optical position sensing arrangement according to the present invention. Referring to Figure 1, light derived from a white light source 1 is conveyed by an optical fibre 2 (i.e. Iighttransmission fibre) to a remote location where it is utilisedforthe illumination of a holographic zone plate 3 in spaced relationship with the light emerging end ofthe optical fibre 2. The zone plate may be attached to a linearly movable body (notshown) while the end of the lighttransmission fibre 2 be fixed. Monochromatic light reflected by the zone plate 3 is arranged to be collected by the optical fibre 4(i.e. lightcollectingfibre)whichconveysthe collected lightto a wavelength analyser 5. The wavelength of the collected lightwhich will be determined by the analyser 5 will be dependent upon the distance L between the co-terminous ends ofthe fibres 2 and 4 and the zone plate 3. Anyvariation in this distance Twill cause a change in the wavelength ofthe collected monochromatic light which will be detected by the analyser 5 and provide an indication of the position or displacement of the zone plate 3 relative to the fixed end of the optical fibre 2. As can be appreciated from Figure 1, some ofthe cone of light emerging from the optical fibre 2 may fail to impinge on the zone plate 3, more especially as the distance L increases. Consequently, the overall optical efficiency of the sensing arrangement is reduced necessitating, more powerful white light sources and/or more sophisticated wavelength analysers. In accordance with the invention, the efficiency of such position sensing arrangements is improved, as depicted in Figure 2, by providing a lens 6which is interposed between the co-terminous ends ofthe light transmission and light collecting fibres 2 and 4 andthe holographiczone plate 3. In view ofthe smallerangleofthecone of light emerging fromthe lens 6 all, or substantially all, of the light emerging from the end of the light transmission fibre 2 effectively impinges on the zone plate 3. CLAIMS
1. An optical position sensing arrangement comprising two optical fibres and a holographic zone plate which are relatively movable, in which lens means is interposed between the co-terminous ends of said optical fibres, along one of which (i.e.
lighttransmission fibre) light is conveyed from a remote white light source, and the zone plate, whereby all ofthe light emerging from the end ofthe light transmission fibre is focused by the lens means on to the zone plate and in which the co-terminous end ofthe otheroptical fibre (i.e. light coliecting fibre) collects all of the light which is reflected from the zone plate and conveys itto a wavelength analyser for determining the wavelength of the collected light which is indicative of the distance between the zone plate and the co-terminous ends of the said one fibre.
2. An optical position sensing arrangement substantially as hereinbefore described with reference to Figure 2.
GB8606550A 1986-03-17 1986-03-17 Improvements relating to optical position sensing arrangements Expired GB2188143B (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB8606550A GB2188143B (en) 1986-03-17 1986-03-17 Improvements relating to optical position sensing arrangements
JP62501799A JPS63502852A (en) 1986-03-17 1987-03-17 Improvements related to optical position sensing devices
PCT/GB1987/000182 WO1987005689A1 (en) 1986-03-17 1987-03-17 Improvements relating to optical position sensing arrangements
EP19870901593 EP0273918A1 (en) 1986-03-17 1987-03-17 Improvements relating to optical position sensing arrangements

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8606550A GB2188143B (en) 1986-03-17 1986-03-17 Improvements relating to optical position sensing arrangements

Publications (3)

Publication Number Publication Date
GB8606550D0 GB8606550D0 (en) 1986-04-23
GB2188143A true GB2188143A (en) 1987-09-23
GB2188143B GB2188143B (en) 1989-12-20

Family

ID=10594739

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8606550A Expired GB2188143B (en) 1986-03-17 1986-03-17 Improvements relating to optical position sensing arrangements

Country Status (4)

Country Link
EP (1) EP0273918A1 (en)
JP (1) JPS63502852A (en)
GB (1) GB2188143B (en)
WO (1) WO1987005689A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110705689B (en) * 2019-09-11 2021-09-24 清华大学 Continuous learning method and device for distinguishing features

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2115139A (en) * 1982-02-10 1983-09-01 Marconi Co Ltd Remote monitoring of the position of a member
GB2129930A (en) * 1982-10-23 1984-05-23 Plessey Co Plc Improvements relating to optical detecting monitoring or measuring arrangements
GB2141541A (en) * 1983-06-14 1984-12-19 British Petroleum Co Plc Optical transducers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2115139A (en) * 1982-02-10 1983-09-01 Marconi Co Ltd Remote monitoring of the position of a member
GB2129930A (en) * 1982-10-23 1984-05-23 Plessey Co Plc Improvements relating to optical detecting monitoring or measuring arrangements
GB2141541A (en) * 1983-06-14 1984-12-19 British Petroleum Co Plc Optical transducers

Also Published As

Publication number Publication date
EP0273918A1 (en) 1988-07-13
WO1987005689A1 (en) 1987-09-24
GB2188143B (en) 1989-12-20
GB8606550D0 (en) 1986-04-23
JPS63502852A (en) 1988-10-20

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930317