Absolute angle measuring device and absolute angle measuring method

摘要

PROBLEM TO BE SOLVED: To provide a technique for accurately acquiring an absolute attitude angle of a measuring object in a non-contact manner.SOLUTION: An equal frequency interval multi-wavelength laser light source (namely, femtosecond laser) 1 is used as measuring light 3, and primary diffraction light 6 generated when the measuring light is incident on a diffraction grating 5 mounted on a measuring object 10 is condensed by a condenser lens 7, at the time, a condensing spot group obtained on a rear focal plane of the condenser lens 7 is used as an angle scale com, for acquiring an absolute attitude angle of the measuring object 10 mounting the diffraction grating 5. Intervals between spots of the condensing spot group are determined by a wavelength of flux corresponding to each spot, and the laser light source used herein can control the frequency accurately, so that the wavelength of each flux is stabilized, as the result, the angle scale com as the laser spot group having the stable spot intervals, is obtained.SELECTED DRAWING: Figure 1