Patent ID: 9658054
Date: 2017-05-23
CPC Classifications: G01B

Claim:
1. An optical measuring apparatus comprising: a light source configured to emit a laser beam; an optical splitter configured to split the laser beam into a first beam and a second beam; a lens configured to focus the first beam as a signal beam onto a target to be measured to irradiate the target to be measured with the signal beam; a light reflector configured to reflect the second beam as a reference beam without irradiating the target to be measured; a lens actuator configured to move the lens; a control unit configured to control the lens actuator to move a focus position of the first beam by moving the lens at least in an optical axis direction during measurement; interference optics configured to multiplex a signal beam reflected by or scattered by the target to be measured with the reference beam, thereby generating three or more interference beams with different phases; and a plurality of photodetectors configured to detect the interference beams, wherein the control unit is further configured to control the lens actuator to move the focus position of the first beam in the optical axis direction within a scanning range such that a coherence length of the laser beam is greater than or equal to a change in an optical path length of the signal beam.