Patent ID: 6124961
Filing Date: 2000-09-26
Classification: G03B

Abstract:
A scanner comprising:a rotatably movable member for rotatably moving on a predetermined rotation axis;a rotary mechanism for causing said rotatably movable member to rotatably move on the rotation axis; andangle detection means for detecting a rotation angle of said rotatably movable member on the rotation axis, said angle detection means comprising an interference optical system for generating an interference light, and a light receiver for receiving the interference light generated by said interference optical system,wherein said interference optical system comprises a light source for emitting a coherent light, and two reflection optical members fixed to said rotatably movable member in such a manner that said two reflection optical members are arranged in a direction intersecting a direction of the rotation axis so as to be placed in alignment at a regular interval, each of said reflection optical members reflecting an incident light and emitting a reflected light toward an opposite direction to an incident direction of the incident light independently of a rotary position of said rotatably movable member, and said interference optical system divides the coherent light emanated from said light source into two parts to be introduced to the respective said two reflection optical members, and superposes coherent lights reflected from said two reflection optical members on each other, by generating the interference light caused by the coherent lights, andwherein each of said reflection optical members includes three mutually perpendicular intersecting reflecting surfaces; andwherein a distance of each said reflective optical member from said light source varies in accordance with a rotation of said rotatably movable member.