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US RE40,551 E1Granted
Device for measuring translation, rotation or velocity via light beam interference
OwnerOlivier M. Parriauxinventor
Life of this patent
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Abstract
The device for measuring translation, rotation or velocity includes at least a light source, a light detector, a first grating and a second grating, the first grating being mobile relative to the second grating. A incident beam reaches the first grating where it is diffracted in two beams whose directions are interchanged by the second grating, the resulting beams being then again diffracted by the first grating in an output diffraction direction where they interfere together. Both gratings are used in reflexion.
Claims41
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant portion of the incident light beam emitted from the light source interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a fixed first reflective grating assembly and a mobile second reflective grating assembly, ;
- wherein the mobile first grating assembly is mobile along a given displacement relative to the fixed second grating assembly;
- , wherein the fixed reflective grating assembly and the mobile reflective grating assembly diffract first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby producing interference and the resultant portion of the incident light beam detected by the at least one light detector forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction, and wherein the resultant interference beam is directed at a resultant angle in a plane perpendicular to lines along which the first grating assembly and the second grating assembly are formed, the resultant angle having a value substantially equal to an angle of incidence in this perpendicular plane of the incident light beam multiplied by <<−1>> relative to an axis perpendicular to the first grating assembly and the second grating assembly, said at least one detector being arranged such that light beams interfering along the resultant-angle are measured by the at least one detector for determining a relative displacement.
2 more elements
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly having a first reflective grating and a second reflective grating assembly having a second reflective grating;
- wherein the grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction, wherein the first grating and the second grating are formed of several longitudinal secondary gratings of close but different frequencies thereby allowing an absolute displacement measurement over at least one range of measurement.
1 more element
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly and a second reflective grating assembly;
- and
- at least one diffraction grating arranged beside at least one of the first grating assembly and the second grating assembly so as to define at least one reference position for the at least one detector;
- wherein the first grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction.
3 more elements
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly and a second reflective grating assembly;
- and
- at least one diffraction grating arranged beside at least one of the first grating assembly and the second grating assembly, said at least one diffraction grating having at least one offset or phase jump, incorporated with the lines of the at least one diffraction grating so as to define at least one reference position for the at least one detector;
- wherein the first grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction.
3 more elements
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly having a first reflective grating and a second reflective grating assembly having a second reflective grating;
- wherein the first grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction, wherein the light source emits the incident light beam so the incident light beam comprises a first partial beam incident upon the fixed grating assembly at a positive angle of incidence and a second partial beam incident upon the fixed grating assembly at a negative angle of incidence, the first grating assembly and the second grating assembly being arranged on either side of two regions of incidence respectively defined by the first partial beam and the second partial beam incident upon the first grating assembly so as to form first to fourth diffracted beams and then to generate at least two resultant interference beams which are detected on either side of the two regions by at least two light detectors arranged on either side of the two regions of incidence.
1 more element
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly having a first reflective grating and a second reflective grating assembly having a second reflective grating, wherein at least one of the first grating or the second grating defines a bi-directional diffraction grating having a same spatial period along two orthogonal axes;
- wherein the first grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction.
1 more element
A device utilizing light diffraction for measuring translation, rotation or velocity, the device comprising:
- a light source emitting an incident light beam;
- at least one light detector for detecting a resultant interference beam;
- a diffraction grating assembly located on a light path of the incident light beam between the light source and the at least one light detector, the diffraction grating assembly comprising a first reflective grating assembly having a first reflective grating and a second reflective grating assembly having a second reflective grating;
- and
- at least first and second reflective surfaces, the first reflective surface arranged to deviate a first beam originating from the source and propagating substantially along a displacement direction of the second reflective grating in order to provide the incident beam, and the second reflective surface arranged to reflect interfering light along the output direction substantially in a direction parallel to the displacement direction before being detected by the at least one detector;
- wherein the first grating assembly is mobile along a given displacement relative to the second grating assembly, wherein the first and second grating assemblies are arranged to diffract at least a portion of the incident light beam, the incident light beam reaching the first grating assembly where the incident light beam is partially diffracted along two different directions thereby forming two partial light beams which reach the second grating assembly, and, thereafter, the first grating assembly, thereby forming, after diffraction by the first grating assembly, the resultant interference beam resulting from interference of the two partial light beams along an output direction.
3 more elements
Dependencies are inferred from the claim text.