| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive apparatus which does not use a high-stability laser, on the occasion of the interferometric measurement of a geometric distance which reduces an influence of the refractive index of air. SOLUTION: When a geometric distance L from a body of an interferometer to a target 110 is accurately measured from distance measurement values D<SB>1</SB>, D<SB>2</SB>obtained by an optical wave interferometric measurement using laser beams of a plurality of wavelengthsλ<SB>1</SB>,λ<SB>2</SB>, while correcting the refractive index of air, the wavelengths of the plurality of laser beams are measured by using an optical comb 104. In that case, the oscillation wavelength of a variable wavelength laser 101 is measured by using the optical comb, and feedback control is performed, whereby laser beams of a plurality of predetermined wavelengths are obtained, or the variable wavelength laser is caused to oscillate at a plurality of arbitrary wavelengths to obtain a plurality of distance measurement values. The wavelengths (frequencies) of laser beams when the respective distance measurement values are obtained are measured by the optical comb, and used in the calculation of the geometric distance. A plurality of lasers 416, 417 are used, and the distance measurement values are obtained while measuring the wavelengths of laser beams oscillated from the respective lasers with the optical comb. COPYRIGHT: (C)2010,JPO&INPIT |
