METHOD AND APPARATUS FOR MEASURING NANOMETER DISPLACEMENT BY LASER SPECKLE

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring nanometer displacements by laser speckle and having high measurement accuracy, and is capable of facilitating processing by using a simple optical system and a simple apparatus.;SOLUTION: The apparatus for measuring nanometer displacements by laser speckle comprises a semiconductor laser 12; a lens 14 for making light from the semiconductor laser 12 converge into a single spot; a beam splitter 16 for branching a leaser beam from the semiconductor laser 12; a reference rough surface 18 to be irradiated with one laser beam branched from the beam splitter 16; and a measuring rough surface 20, to be irradiated with the other laser beam branched from the semiconductor laser 12. The apparatus for measuring the nanometer displacements by laser speckle is provided with both an optical sensor 22 for receiving light produced by superposition via the beam splitter 16 of the laser beams, each being reflected at the reference rough surface 18 and the measuring rough surface 20 and their speckle interference and a computer 26 for determining the displacements of the measuring rough surface 20, on the basis of changes in an output voltage of the optical sensor 22 within a voltage range as a measuring range, in which the output values change substantially linearly between the maximum value and the minimum value of the output of the optical sensor 22 due to the incidence of speckle interference light.;COPYRIGHT: (C)2008,JPO&INPIT