GB2138588A - Optical Grating for Displacement Sensor - Google Patents
Optical Grating for Displacement Sensor Download PDFInfo
- Publication number
- GB2138588A GB2138588A GB08327702A GB8327702A GB2138588A GB 2138588 A GB2138588 A GB 2138588A GB 08327702 A GB08327702 A GB 08327702A GB 8327702 A GB8327702 A GB 8327702A GB 2138588 A GB2138588 A GB 2138588A
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- reflectance
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- 238000006073 displacement reaction Methods 0.000 title claims abstract description 36
- 230000003287 optical effect Effects 0.000 title claims abstract description 36
- 239000000758 substrate Substances 0.000 claims abstract description 44
- 230000005540 biological transmission Effects 0.000 claims abstract description 21
- 230000005855 radiation Effects 0.000 claims abstract description 16
- 230000001419 dependent effect Effects 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 16
- 239000011248 coating agent Substances 0.000 claims description 15
- 238000000576 coating method Methods 0.000 claims description 15
- 230000001464 adherent effect Effects 0.000 claims description 14
- 238000013500 data storage Methods 0.000 claims description 3
- 231100001261 hazardous Toxicity 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 239000011521 glass Substances 0.000 description 6
- 230000007704 transition Effects 0.000 description 5
- 230000033001 locomotion Effects 0.000 description 4
- 239000013307 optical fiber Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 229920002120 photoresistant polymer Polymers 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
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
- G01D5/32—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 attenuation or whole or partial obturation of beams of light
- G01D5/34—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 attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/36—Forming the light into pulses
- G01D5/38—Forming the light into pulses by diffraction gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1866—Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Optical Transform (AREA)
Abstract
An optical grating comprises an ordered array of first and second sets of stripe members, respective members of the first and second sets being alternately disposed in the array. The members (13) of the first set have an optical characteristic whereby the transmission reflectance of the members is substantially independent of the wavelength of radiation incident thereon and may be uncoated substrate (11). The members (12) of the second set have a corresponding optical characteristic which is dependent upon the wavelength of incident radiation and in a first waveband the members (12) of the second set have the same transmission or reflectance as that of the members (13) of the first set whilst in a second wavelength band the members (12) of the second set have a different transmission or reflectance from that of the members (13) of the first set. Displacement sensors incorporating gratings (10) are also disclosed in forming part of displacement transducers. <IMAGE>
Description
SPECIFICATION
Optical Gratings
This invention relates to optical gratings and to displacement sensors and transducers incorporating such gratings.
A known form of optical grating comprises an optically transparent substrate, such as glass, on which is located a set of opaque lines arranged parallel to one another and mutually separated by a predetermined distance.These known gratings have a variety of uses and, in particular, when used as a pair and illuminated by a beam of light they function as a displacement sensor because relative motion of the two gratings provides intensity modulation of the transmitted light beam. The extent of this modulation as measured by a detector forming part of a transducer provides a measure of the displacement.However any variation in the characteristics of the gratings or the illuminating light beam or the detector such as may arise from variations in the electrical supply voltage to the detector and to the light source or due to ageing of the components, gives rise to errors in the displacement measure.
It is an object of the present invention to provide an improved form of optical grating which when used in an optical grating displacement sensor forming part of a transducer permits the foregoing disadvantages to be obviated or mitigated.
According to the present invention there is provided an optical grating comprising an ordered array of first and second sets of stripe members, respective members of the first and second sets being alternately disposed in the array, wherein the members of the first set have an optical characteristic whereby the transmission or reflectance of the members is substantially independent of the wavelength of radiation incident thereon, and the members of the second set have a corresponding optical characteristic which is dependent upon the wavelength of incident radiation such that in a first wavelength band the members of the second set have the same transmission or reflectance as that of the members of the first set and in a second wavelength band the members of the second set have a different transmission or reflectance from that of the members of the first set.
In one form of the grating the first and second sets of the array are carried by a transparent substrate and the second set is formed by a coating adherent to said substrate, said coating being material forming an interference cut-off filter and said first set is formed by uncoated parts of the substrate.
In another form of the grating a substrate made of material forming an interference cut-off filter is provided, and said first set is formed by a coating adherent to said substrate and defining highreflectance first members, said second set being formed by uncoated parts of said substate.
In a still further form of the grating a substrate made of material forming an absorption filter and adherent to a high-reflectance layer is provided, and said first set is formed by a coating adherent to said substrate and defining high-reflectance first members, said second set being formed by uncoated parts of said substrate.
Optical gratings in accordance with the present invention may form a part of or the whole of a displacement sensor having first and second optical gratings. Such sensors find utility in displacement transducers which comprise lightbeam-delivery means arranged to deliver a first beam of light in said first wavelength band to the sensor, and to deliver a second beam of light in said second wavelength band to the sensor, lightbeam-collection means arranged to collect said first and second beams from the sensor, and detector means at the output of the collection means for measuring the ratio of intensities of the first and second beams thereat.
According to the type of optical grating in accordance with the present invention which is utilised in the displacement sensor the sensor may operate either in a transmission mode or in a reflection mode. In any event it will be appreciated that the sensors provide intensity modulation of one of the two light beams as a result of movement of one of the two gratings of the sensor whilst the other of the two light beams is not subjected at all to intensity modulation or is only so subjected to a small extent despite the grating movement and this beam therefore functions as a reference light beam. If the reference beam is subjected to a small degree of intensity modulation by grating movement this can be calibrated out electronically.In consequence any variation of intensity arising from ageing or any variation in the characteristics of the components of the transducer is detected by the detector means and because the output thereof is in the form of a ratio of intensities the displacement measure is rendered independent of the characteristics of the components used in the transducer.
The light beam delivery means may comprise a single light source emitting a broad band of light, a first part of that band forming the first beam of light and a second part of that band forming the second beam of light as determined by the transition wavelength of the second set of members of the grating according to the present invention. Alternatively, the light beam delivery means may comprise a first light source emitting only the first beam of light and a second light source emitting only the second beam of light.
It will be appreciated that if only one broad band light source is used the transition wavelength must be sufficiently sharp to eliminate ambiguity between the first and second beams whereas if two separate light sources are used the precise nature of the transition wavelength need not be critical. However the wavelengths of the first and second beams should preferably be sufficiently close as to avoid or minimise divergence of effects such as Raleigh scattering.
The light-beam-collection means may incorporate a beam splitter for separately delivering the first and second light beams to the detector means. In this arrangement the detector means comprises separate detector components respectively for detecting the intensities of the first and second light beams. Alternatively only a single detector element may be used and the transducer arranged to provide the first and second beams separated in time. In this arrangement the detector means may incorporate a data storage facility and this arrangement has the advantage that any deterioration or variation in the characteristics of the single detector element will not affect the displacement measurement.
The detector means may incorporate any known arrangement for providing the required ratio, such as a voltage divider. The light source or sources previously referred to may be in the form of laser diodes in which case feedback systems could be used to keep the output intensity stable with time. Alternatively the light source may be in the form of a light emitting diode in which case a measure of the output intensity is directly delivered to the detector means and the pulsing rate of the light emitting diode arranged so that the detector means separately receives signals from the sensor and directly from the light emitting diode, the intensity ratio of which signals eliminates dependence on variation of the intensity of the light emitting diode.
Preferably the light-beam-delivery means and the light-beam-collection means each incorporate optical fibres in order to render the transducer suitable for use in hazardous environments.
The embodiments of the present invention will now be described by way of example with reference to the accompanying schematic drawings in which:
Fig. 1 illustrates an optical grating according to the present invention;
Fig. 2 illustrates a first embodiment of displacement transducer according to the present
invention;
Fig. 3 illustrates a second embodiment of displacement transducer according to the present
invention; and
Fig. 4 illustrates a third embodiment of optical
transducer according to the present invention.
The grating 10 illustrated in Fig. 1 comprises a
glass substrate 11 having a front surface 1 A on which are located a set of lines 12 which extend
parallel to one another adjacent lines being
separated by stripes 1 3. The stripes 1 3 are formed by uncoated regions of the substrate 11
and therefore have the transmission
characteristics of the substrate 11 which are
independent of the wavelength of incident
radiation. The lines 12 however are each formed
by a coating adherent to surface 1 A and made of
a material which exhibits selective transmissivity
according to the wavelength band of incident
radiation.By way of example the lines 12 may be
formed by a coating having one or more layers functioning as an interference filter which is transmissive below a predetermined wavelength (the transition wavelength) and non-transmissive at wavelengths above the predetermined wavelength.
Fig. 2 illustrates a sensor 50 formed by a pair of gratings 10 each as described with reference to Fig. 1. This sensor 50 is operable in the transmission mode so that incident light is transmitted through the sensor 50 being intensity modulated or unmoduiated according to whether the wavelength band is above or below the transition or predetermined wavelength of the lines 12.
In the sensor 50 the lines 12 of the gratings 10 have the characteristic of being transmissive to wavelengths below the predetermined wavelength and non-transmissive to wavelengths above the predetermined wavelength. It will however be appreciated that the inverse arrangement could be utilised in which case the lines 1 2 would be non-transmissive below the predetermined wavelength and transmissive above the predetermined wavelength. In either case the incident beam of light which is at a wavelength to which the lines 1 2 are transmissive functions as a reference beam and accordingly the precise transmission characteristic of the lines 1 2 together with that part of the substrate 11 on which the lines 12 are located must be equal to that of the stripes 1 3.Furthermore, the incident beam of light which is at a wavelength to which the lines 12 are non-transmissive functions as a signal beam, being intensity-modulated by the displacement of one grating 10 relative to the other grating 10 in the sensor 50.
Fig. 3 illustrates a sensor 54 incorporating a grating 55 having a glass substrate 56 on which are located non-transmissive lines 57 which may be either mirror lines or opaque lines and which
remain non-transmissive irrespective of the wavelength of the incident radiation (i.e. grating
55 is a standard known grating). Sensor 54 also
includes a grating 10 as described with reference to Fig. 1. This sensor is operable in the transmission mode in that both signal and
reference beams are transmitted through the
sensor 54 but in this case the reference beam is
subjected to an intensity attenuation (of the order of 50%) caused by the presence of lines 57.
Fig. 4 illustrates a sensor 60 incorporating a standard or known grating 61 having opaque
lines 63 on a glass substrate 62. The second grating 66 of sensor 60 is formed by mirror lines
65 mounted on a substrate 64 made of material forming an interference filter. Accordingly this sensor 60 operates in the reflectance mode and the reference beam caused by the presence of
lines 63 is subjected to an intensity attenuation when substrate 64 is non-transmissive (and non
reflective). Likewise the signal beam in addition to being modulated is intensity attenuated by the presence of the substrate 64 when in its transmissive form.
Fig. 5 illustrates a sensor 70 incorporating a standard or known grating 71 having opaque lines 72 on a glass substrate 73. The second grating 76 is formed by high-reflectance or mirror lines 75 on a substrate 74 formed by an absorbing filter material 77 adherent to a highreflectance or mirror coating 78. Accordingly sensor 70 operates in the reflectance mode and the reference beam, although subject to intensity attenuation is formed by material 77 in its fully transmissive mode whereby the entirety of grating 76 is highly reflective and simply acts as a mirror. The signal beam, of course, is formed by reflectance from lines 75 when filter material 77 is in its opaque or absorbing mode.
By way of example various embodiments of displacement transducers will now be described by way of example utilising the sensor 50 of Fig. 2 i.e. a transmissive-mode transducer but it will be understood that the other sensors 54, 60, 70, previously described may be substituted for sensor 50 with appropriate allowance being made in collection of the light beams from the sensor where the sensor operates in the reflectance mode.
In the transducer 20 illustrated in Fig. 6 the sensor 50 is interrogated with light delivered along optical fibre 22 and the transmitted light is collected by optical fibre 23, fibres 22 and 23 together forming a duplex optical fibre cable.
Light is fed into fibre 22 by a self-focussing lens 24 from a broad band source 25 which in this instance is formed by a light emitting diode having a centre wavelength of 820 nm. The lines 12 of each grating 10 of the sensor 50 have a transmission cut-off wavelength of 830 nm so that source 25 simultaneously provides the first light beam formed by wavelengths below 830 nm and the second light beam formed by those wavelengths above 830 nm. Fibre 23 delivers the collected light beams to a self-focussing lens 26 the output of which is incident on a beam splitter 27 so that those frequencies which form the first light beam are transmitted through the beam splitter 27 to a first photodiode 28 and those frequencies forming the second light beam are reflected from the beam splitter 27 onto a second photodiode 29.Each photodiode 28, 29 measures the intensity of the light beam delivered thereto and the electrical outputs from the photodiodes 28, 29 are delivered to a voltage divider 30 which provides at its output 31 the ratio of intensities. It will be appreciated that the characteristics of the beam splitter 27 require to
be pre-arranged to be comparable with those of the lines 12 of the gratings 10 insofar as beam splitter 27 transmits the first beam substantially without loss and reflects the second beam substantially without loss.
In the second transducer illustrated in Fig. 7 the light source 25 comprises a first laser diode 35 having a narrow bandwidth at 840 nm, a second laser diode 36 having a narrow bandwidth at 904 nm and a beam splitter 37 arranged to be transmissive to the light beam from laser diode 35 and reflective to the beam from laser diode 36.
Beam splitter 37 is arranged to reflect a small percentage of the light from diode 35 and to transmit the same small percentage of light from laser diode 36, these being detected by a photodiode 38 the output of which is delivered as a feedback signal to the pulsing circuit and power supply 39 which alternately drives the diodes 35, 36 so that their output beams are time interlaced.
The optical fibre 23 delivers the two time interlaced light beams to a single photodiode 41 the electrical output of which is delivered to processing circuitry 42 which incorporates a data store and a data ratioing device.
In the second transducer the transmission cutoff wavelength of the lines 12 of the gratings 10 is 870 nm.
It will be appreciated that the two laser diodes 35, 36 of the Fig. 7 embodiment could be respectively replaced by light emitting diodes in combination with narrow band filters. For example a light emitting diode having a centre wavelength of 820 nm in combination with an
Ealing narrow band filter having a centre wavelength of 820 nm on the one hand and a light emitting diode having a centre wavelength of 900 nm in combination with an Ealing narrow band filter having a center wavelength of 900 nm on the other hand.
If will also be appreciated that beam splitter 37 which functions as a device for combining the two beams of light could be replaced by an optical four-point coupler.
In the transducer illustrated in Fig. 8 fluctuation in intensity of the light beams emitted by the two light sources 35, 36 is monitored by sampling the light output therefrom and coupling the sampled light onto the photodiode 41 by means of beam splitters 45, 46.
By way of example the gratings 10 of Fig. 1 can be manufactured by photolithographic techniques. First, the glass substrate is coated with the material from which the lines are to be formed and then the material is overlaid with a layer of photoresist which is exposed to ultra violet light through a master diffraction grating.
The photoresist is then developed and suitably etched using a silicon dioxide etch.
Although each transducer described forms a single transducer system it may be utilised in a passively multiplexed system by using a range of source wavelength pairs.
It will also be appreciated that to provide simultaneous signal and reference beams at the detector, two separate light beam sources may be used each beam being frequency modulated and being separated at the detector by demodulation.
This arrangement eiiminates the need to store data in the manner previously discussed.
Claims (11)
1. An optical grating comprising an ordered array of first and second sets of stripe members, respective members of the first and second sets being alternately disposed in the array, wherein the members of the first set have an optical characteristic whereby the transmission or reflectance of the members is substantially independent of the wavelength of radiation incident thereon, and the members of the second set have a corresponding optical characteristic which is dependent upon the wavelength of incident radiation such that in a first wavelength band the members of the second set have the same transmission or reflectance as that of the members of the first set and in a second wavelength band the members of the second set have a different transmission or reflectance from that of the members of the first set.
2. An optical grating as claimed in claim 1, wherein the first and second sets of the array are carried by a transparent substrate and the second set is formed by a coating adherent to said substrate, said coating being material forming an interference cut-off filter, and said first set is formed by uncoated parts of the substrate.
3. An optical grating as claimed in claim 1, comprising a substrate made of material forming an interference cut-off filter, and said first set is formed by a coating adherent to said substrate and defining high-reflectance first members, said second set being formed by uncoated parts of said substrate.
4. An optical grating as claimed in claim 1,
comprising a substrate made of material forming
an absoprtion filter and adherent to a high
reflectance layer, and said first set is formed by a coating adherent to said substrate and defining
high-reflectance first members, said second set
being formed by uncoated parts of said substrate.
5. A displacement sensor comprising first and second optical gratings, each of which gratings is
as claimed in claim 2.
6. A displacement sensor comprising first and
second optical gratings, wherein said first grating
comprises a transmissive substrate carrying lines
having an optical characteristic whereby the
transmission or reflectance of the lines is
independent of the wavelength of radiation
incident thereon, and said second grating is as
claimed in claim 2.
7. A displacement sensor comprising first and
second optical gratings, wherein said first grating
comprises a transmissive substrate carrying lines
which are non-transmissive and non-reflective
independently of the wavelength of radiation
incident thereon, and said second grating is as
claimed in either claim 3 or claim 4.
8. A displacement transducer comprising a
displacement sensor as claimed in any one of
claims 5-7, in combination with light-beam
delivery means arranged to deliver a first beam of
light in said first wavelength band to the sensor,
and to deliver a second beam of light in said
second wavelength band to the sensor, light
beam-collection means arranged to collect said
first and second beams from the sensor, and
detector means at the output of the collection
means for measuring the ratio of intensities of the
first and second beams thereat.
9. A displacement transducer as claimed in claim 8, wherein the light-beam delivery means and the light-beam collection means each incorporate optical fibres in order to render the transducer suitable for use in hazardous environments.
10. A displacement transducer as claimed in claim 8 or claim 9, wherein the detector means comprises first and second detector components and the light beam collection means incorporates a beam splitter for separately delivering the first and second light beams to the respective detector components of the detector means.
11. A displacement transducer as claimed in claim 10, wherein said detector means further comprises a data storage device for storing the intensity data of one beam until the intensity of the other beam is detected to permit measurement of said intensity ratio.
1 2. A displacement sensor substantially as hereinbefore described with reference to any one of the embodiments illustrated in the accompanying drawings.
1 3. A displacement transducer substantially as hereinbefore described with reference to any one of the embodiments illustrated in the accompanying drawings.
11. A displacement transducer as claimed in claim 8 or claim 9, wherein the detector means comprises a single detector component and the light-beam delivery means is arranged to provide the first and second beams separated in time.
1 2. A displacement transducer as claimed in claim 11, wherein said detector means further comprises a data storage device for storing the intensity data of one beam until the intensity of the other beam is detected to permit measurement of said intensity ratio.
1 3. A displacement transducer substantially as hereinbefore described with reference to any one of the embodiments illustrated in the accompanying drawing.
New Claims or Amendments to Claims Filed on 4
April 1984.
Superseded Claims 1-13.
New or Amended Claims.
1. A displacement sensor comprising first and second optical gratings of which said first grating is movable relative to said second grating to provide intensity modulation of an interrogating radiation beam, each said grating comprising an ordered array of first and second sets of stripe members, respective members of the first and second sets being alternately disposed in the array, the stripe members of the first and second gratings being parallel, wherein one of said first and second optical gratings incorporates stripe members of the first set having an optical characteristic whereby the transmission or reflectance of the members is substantially independent of the wavelength of radiation incident thereon, and the stripe members of the second set have a corresponding optical characteristic which is dependent upon the wavelength of incident radiation such that in a first wavelength band the members of the second set have the same transmission or reflectance as that of the members of the first set and in a second wavelength band the members of the second set have a different transmission or reflectance from that of the members of the first set.
2. A sensor as claimed in claim 1, wherein in said one grating the first and second sets of the array are carried by a transparent substrate and the second set is formed by a coating adherent to said substrate, said coating being material forming an interference cut-off filter, and said first set is formed by uncoated parts of the substrate.
3. A sensor as claimed in claim 1, wherein said one grating comprises a substrate made of material forming an interference cut-off filter, and said first set is formed by a coating adherent to said substrate and defining high-reflectance first members, said second set being formed by uncoated parts of said substrate.
4. A sensor as claimed in claim 1, wherein said one grating comprises a substrate made of material forming an absorption filter and adherent to a high-reflectance layer, and said first set is formed by a coating adherent to said substrate and defining high-reflectance first members, said second set being formed by uncoated parts of said substrate.
5. A sensor as claimed in claim 2, wherein the other of said first and second gratings comprises a transmissive substrate carrying lines having an optical characteristic whereby the transmission or reflectance of the lines is independent of the wavelength of radiation incident thereon.
6. A sensor as claimed in either of claims 3 and 4, wherein the other of said first and second gratings comprises a transmissive substrate carrying lines which are non-transmissive and non-reflective independently of the wavelength of radiation incident thereon.
7. A displacement transducer comprising a displacement sensor as claimed in any one of claims 1-6, in combination with light-beamdelivery means arranged to deliver a first beam of light in said first wavelength band to the sensor, and to deliver a second beam of light in said second wavelength band to the sensor, lightbeam-collection means arranged to collect said first and second beams from the sensor, and detector means at the output of the collection means for measuring the ratio of intensities of the first and second beams thereat.
8. A displacement transducer as claimed in claim 7, wherein the light-beam delivery means and the light-beam collection means each incorporate optical fibres in order to render the transducer suitable for use in hazardous environments.
9. A displacement transducer as claimed in claim 7 or claim 8, wherein the detector means comprises first and second detector components and the light beam collection means incorporates a beam splitter for separately delivering the first and second light beams to the respective detector components of the detector means.
10. A displacement transducer as claimed in claim 7 or claim 8, wherein the detector means comprises a single detector component and the light-beam delivery means is arranged to provide the first and second beams separated in time.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08327702A GB2138588B (en) | 1983-04-19 | 1983-10-17 | Optical grating for displacement sensor |
| DE19843414590 DE3414590A1 (en) | 1983-04-19 | 1984-04-18 | OPTICAL SENSOR SENSOR AND THE SENSOR THEREFORE |
| FR8406229A FR2544875B1 (en) | 1983-04-19 | 1984-04-19 | OPTICAL DISPLACEMENT SENSOR |
| NL8401284A NL8401284A (en) | 1983-04-19 | 1984-04-19 | OPTICAL MOVEMENT SCAN. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB838310567A GB8310567D0 (en) | 1983-04-19 | 1983-04-19 | Optical gratings |
| GB08327702A GB2138588B (en) | 1983-04-19 | 1983-10-17 | Optical grating for displacement sensor |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8327702D0 GB8327702D0 (en) | 1983-11-16 |
| GB2138588A true GB2138588A (en) | 1984-10-24 |
| GB2138588B GB2138588B (en) | 1987-07-29 |
Family
ID=26285867
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08327702A Expired GB2138588B (en) | 1983-04-19 | 1983-10-17 | Optical grating for displacement sensor |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3414590A1 (en) |
| FR (1) | FR2544875B1 (en) |
| GB (1) | GB2138588B (en) |
| NL (1) | NL8401284A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0231538A1 (en) * | 1985-12-06 | 1987-08-12 | Philips Patentverwaltung GmbH | Optical path sensor with a filter |
| EP0626563A1 (en) * | 1993-05-21 | 1994-11-30 | Robert Bosch Gmbh | Position measuring device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB356430A (en) * | 1929-08-14 | 1931-09-10 | Stanley Bernard Freiberg | Loose leaf binders |
| GB506667A (en) * | 1936-12-07 | 1939-06-01 | Virgil Bernard Sease | Improvements in or relating to the production of diffration gratings and of multi-colour screens for use in colour photography |
| GB1092882A (en) * | 1963-01-31 | 1967-11-29 | Emi Ltd | Improvements relating to the generation of electrical signals representing colour components of an image |
| GB1352001A (en) * | 1970-08-05 | 1974-05-15 | Balzers Patent Beteilig Ag | Optical diffraction filters |
| GB1591644A (en) * | 1976-10-06 | 1981-06-24 | Philips Nv | Arrangement including a diffraction grating for the formation of colour components |
| GB1592902A (en) * | 1978-01-17 | 1981-07-08 | Rca Corp | Diffractive-subtractive light filter blank |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE411955B (en) * | 1978-06-02 | 1980-02-11 | Asea Ab | FIBEROPTICAL METDON WITH MOST TWO FIBERS |
-
1983
- 1983-10-17 GB GB08327702A patent/GB2138588B/en not_active Expired
-
1984
- 1984-04-18 DE DE19843414590 patent/DE3414590A1/en not_active Withdrawn
- 1984-04-19 FR FR8406229A patent/FR2544875B1/en not_active Expired - Fee Related
- 1984-04-19 NL NL8401284A patent/NL8401284A/en not_active Application Discontinuation
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB356430A (en) * | 1929-08-14 | 1931-09-10 | Stanley Bernard Freiberg | Loose leaf binders |
| GB506667A (en) * | 1936-12-07 | 1939-06-01 | Virgil Bernard Sease | Improvements in or relating to the production of diffration gratings and of multi-colour screens for use in colour photography |
| GB1092882A (en) * | 1963-01-31 | 1967-11-29 | Emi Ltd | Improvements relating to the generation of electrical signals representing colour components of an image |
| GB1352001A (en) * | 1970-08-05 | 1974-05-15 | Balzers Patent Beteilig Ag | Optical diffraction filters |
| GB1591644A (en) * | 1976-10-06 | 1981-06-24 | Philips Nv | Arrangement including a diffraction grating for the formation of colour components |
| GB1592902A (en) * | 1978-01-17 | 1981-07-08 | Rca Corp | Diffractive-subtractive light filter blank |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0231538A1 (en) * | 1985-12-06 | 1987-08-12 | Philips Patentverwaltung GmbH | Optical path sensor with a filter |
| EP0626563A1 (en) * | 1993-05-21 | 1994-11-30 | Robert Bosch Gmbh | Position measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2138588B (en) | 1987-07-29 |
| GB8327702D0 (en) | 1983-11-16 |
| DE3414590A1 (en) | 1984-10-25 |
| FR2544875B1 (en) | 1990-03-02 |
| FR2544875A1 (en) | 1984-10-26 |
| NL8401284A (en) | 1984-11-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |