Patent ID: 8514382

Claim:
An optical device ( 20 ) for measuring rotation of an object ( 2 ), comprising: a light source ( 4 ) emitting a collimated incident light beam ( 8 ) propagating in an incident direction; a reflecting plane optical interface ( 13 , 23 ) fastened to the object ( 2 ), the rotation of which is desired to measure, and capable of forming a first reflected beam ( 15 ); a cube-corner retroreflector ( 12 ) fastened to the object ( 2 ), said cube corner ( 12 ) comprising reflecting plane faces ( 14 , 14 ′, 14 ″) forming a second reflected beam ( 16 ) in a direction parallel to the incident direction; a source-sensor unit comprising the light source ( 4 ) and a sensing system ( 17 ), the sensing system ( 17 ) measuring, a displacement Δ 1 of the first reflected beam ( 15 ), reflected by the reflecting plane optical interface ( 13 , 23 ) and a displacement Δ 2 of the second reflected beam ( 16 ), reflected by the reflecting faces ( 14 , 14 ′, 14 ″) of the cube corner ( 12 ), the displacements Δ 1 and Δ 2 being respectively measured with respect to an initial position of the first reflected beam ( 15 ) and of the second reflected beam ( 16 ); and a processing system calculating, as a function of the measurement of the displacement Δ 1 and of a distance D 1 between the sensing system ( 17 ) and the reflecting plane optical interface ( 13 , 23 ) and of the measurement of the displacement Δ 1 and of a distance D 2 between the sensing system ( 17 ) and the cube corner ( 12 ), a measurement of the rotation α of the object ( 2 ) between an initial position and a measurement position, the processing system configured to calculate said measurement of the rotation α as a function of an arithmetic sum of Δ 1 and Δ 2 divided by the distance D 2 between the sensing system ( 17 ) and the cube corner ( 12 ) so that said measurement of the rotation α eliminates parasitic rotation β from the source-sensor unit.