Patent ID: 7333185
Filing Date: 2008-02-19
Classification: G01P,G01S

Abstract:
1. An optical velocimeter comprising: a light-emitting element for emitting coherent light; a light branch section for branching light emitted from the light-emitting element into at least three light fluxes; an optical system for intersecting on a measured object optical axes of the respective light fluxes branched by the light branch section one another to form one detection point; at least two light-receiving sections for receiving scattered light frequency-shifted by travel of the measured object from the detection point, wherein the number of light-receiving sections is greater than the number of light-emitting elements; and a signal processing circuit for processing light-reception signals outputted from the at least two light-receiving sections to detect at least two directions of traveling velocity of the measured object, wherein: the light fluxes for forming the detection point are three light fluxes which are a first light flux, a second light flux and a third light flux; the optical system includes a deflection section for deflecting optical axes of the second light flux and the third light flux, and a polarization state change section for changing polarization state so that at least a polarization state of the first light flux is different from polarization states of the second and third light fluxes; the light-receiving section has a first light-receiving section for receiving scattered light of the first light flux and scattered light of the second light flux which are different from each other in polarization state, and a second light-receiving section for receiving scattered light of the first light flux and scattered light of the third light flux which are different from each other in polarization state; the first light-receiving section and the second light-receiving section respectively include a dividing section for dividing incident scattered light into two, and two photodetectors for respectively receiving the divided scattered lights divided by the dividing section through mutually orthogonal polarizers; and the signal processing circuit determines travel direction of the measured object and detects two-dimensional travel velocity of the measured object based on two light-reception signals having difference in phase caused by difference of polarization states obtained by the two photodetectors of the respective light-receiving sections.