Patent ID: 7049578
Filing Date: 2006-05-23
Classification: G01F,G01P

Abstract:
1. An optical movement information detector comprising: a semiconductor light-emitting device which emits coherent light; an optical branching device which splits the coherent light emitted from the semiconductor light-emitting device into a first light flux and a second light flux; a first optical system which applies at least one of the first and second light fluxes split by the optical branching device to a moving object to be measured; a phase changing section which is arranged on an optical axis of either one of the first and second light fluxes of the first optical system and changes a phase of light; a second optical system which guides to a first photodetector and a second photodetector, interference light caused by scattered light from the object to be measured when both the first and second light fluxes are applied to the object to be measured or interference light caused by interference of one of the first and second light fluxes with scattered light from the object to be measured when the other of the first and second light fluxes is applied to the object to be measured; an interference light splitting section for splitting the interference light caused by the scattered light from the object to be measured of the second optical system into two different phase components having two different phases defined by the phase changing section and making the first and second photodetectors receive the split two different phase components; a first signal processing circuit section which receives a light reception signal from the first photodetector and outputs a first signal that represents one phase component of the interference light; a second signal processing circuit section which receives a light reception signal from the second photodetector and outputs a second signal that represents the other phase component of the interference light; a third signal processing circuit section which outputs a third signal of an interference light signal whose noise component is removed by using the first signal from the first signal processing circuit section and the second signal from the second signal processing circuit section; and a movement velocity detection section which detects a frequency of the third signal from the third signal processing circuit section and detects a movement velocity of the object to be measured on the basis of the frequency.