| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact, inexpensive and highly efficient heterodyne interferometric displacement measurement apparatus. <P>SOLUTION: The heterodyne interferometric displacement measurement apparatus includes: a portion in which a diffraction grating rotating at a fixed speed is irradiated with a laser luminous flux to generate two diffracted luminous fluxes having orders different from each other and a first frequency difference, in which there is generated and output such a synthetic light that the obtained two diffracted luminous fluxes are in the same direction, on the same axis and with their planes of polarization being orthogonal to each other, and in which there is realized a function equivalent to a so-called two-frequency laser light source; a first interference optical system in which a first frequency difference signal is generated by interfering in the synthetic luminous flux with keeping the first frequency difference; and means in which there is generated two luminous fluxes that is made incident to the interference optical system configured such that a difference in an optical path length is in the vicinity of zero and that has a second frequency difference in accordance with a displacement amount of a measured object, in which a second frequency difference signal is generated by interfering the two luminous fluxes, and in which information on the displacement of the measured object is calculated on the basis of information on a difference between the first frequency difference signal and a reference frequency difference signal and output. <P>COPYRIGHT: (C)2012,JPO&INPIT |
