Optical torque sensor utilizing change in reflectance grating line spacing
First Claim
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1. An apparatus for measuring torque on a rotating or stationary shaft under torsion, comprising:
- (a) a light source for emitting a light along a light path;
(b) a light detector having a plurality of light detecting elements; and
(c) a reflection grating provided with grating lines and grating spacing, said reflection grating being fixed to said shaft along said light path and said grating lines being fixed at an angle of 45°
to the length of said shaft, for diffracting said light onto said light detecting elements in an alternating pattern of minima and maxima,whereby said torque causes a change in said grating spacing, said change causes different light detecting elements of said light detector to receive said alternating pattern.
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Abstract
Torque on a rotating or stationary shaft is measured by an apparatus that includes a light source for emitting light along a light path; a reflection grating fixed to the shaft along the light path reflecting and diffracting the light; and a light detector having a plurality of light detecting elements for receiving the reflected and diffracted light. Torque on the shaft produces a change in the grating spacing of the grating, which in turn produces a change of diffraction angle of the reflected light, thereby causing a different element of the light detector to receive the light.
21 Citations
11 Claims
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1. An apparatus for measuring torque on a rotating or stationary shaft under torsion, comprising:
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(a) a light source for emitting a light along a light path; (b) a light detector having a plurality of light detecting elements; and (c) a reflection grating provided with grating lines and grating spacing, said reflection grating being fixed to said shaft along said light path and said grating lines being fixed at an angle of 45°
to the length of said shaft, for diffracting said light onto said light detecting elements in an alternating pattern of minima and maxima,whereby said torque causes a change in said grating spacing, said change causes different light detecting elements of said light detector to receive said alternating pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining the torque on a stationary or rotating shaft using a torque sensor having a light source, a reflection grating having a plurality of grating lines therein and two light detecting elements, said method comprising the steps of:
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(a) fixing said reflection grating to said shaft so that said grating lines are fixed at an angle of 45°
to the length thereof;(b) illuminating said reflection grating with a frequency of light from said light source; (c) recording the relative intensity of diffracted light impinging upon said light detecting elements; and (d) determining the angle of said diffracted light from the relative intensity thereof.
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11. A method for determining the torque on a stationary or rotating shaft using a torque sensor having a light source, a reflection grating having a plurality of grating lines therein, and a plurality of light detecting elements, said method comprising the steps of:
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(a) fixing said reflection grating to said shaft so that said grating lines are fixed at an angle of 45°
to the length thereof,(b) illuminating said reflection grating with a frequency of light; (c) selecting the individual light detecting element that receives the highest intensity of light diffracted from said reflection grating; and (d) determining the angle associated with said individual light detecting element.
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Specification