| 摘要 |
PURPOSE: To improve the measuring accuracy of an optical measuring instrument for measuring the interval between two surfaces by providing light source means which output three light beams having different wavelengths, a reference beam/ output beam separating means having a deflecting means, a beam coupling means, and an optical path difference detecting means. CONSTITUTION: An optical fiber 16 spatially filtrates light rays emitted from laser diodes 12 and 14 and makes the fitting of the optical system 18 of an interferometer easier. The light from the fiber 16 is condensed on the surface of an object through an optical system 17 and separated into an object beam(OB) and reference beam(RB). The beam RB is directed to a mirror 18a connected to a piezoelectric transducer 18b through a reflecting mirror 19. The mirror 18a is vibrated by means of the transducer 18b and adjusts the phase of a beam R13. The light from the optical system 18 is analyzed after the light is reversely passed through the fiber 16 and further passed through a polarization beam splitter 30. The light is separated by means of a diffraction grating 20. Detectors 22, 24, and 26 are separately arranged to detect the intensities of three wavelengths.
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