Patent ID: 7502100
Filing Date: 2009-03-10
Classification: G01B

Abstract:
1. A three-dimensional position measurement method for specifying a position of a part irradiated with measurement light of an object to be measured, based on a projection angle of the measurement light projected onto the object and an acceptance angle of the measurement light reflected from the object, the method comprising: projecting, as the measurement light, circular polarized light or elliptical polarized light onto the object; photoelectrically converting a first portion of reflected light from the object to obtain a first signal; allowing a second portion of the reflected light from the object to enter a quarter wavelength plate; allowing reflected light that has passed through the quarter wavelength plate to enter a polarizing device attenuating secondary reflected light that is light reflected from the object twice; photoelectrically converting reflected light that has passed through the polarizing device to obtain a second signal; performing signal processing, for the first signal or the second signal, of removing secondary reflected light components by using a difference between the first signal and the second signal; and determining a set of the projection angle and the acceptance angle based on a third signal obtained by the signal processing.