Diffraction grating interferometer of large equivalent wavelength for flatness testing of rough surfaces

거친 표면 형상측정을 위한 큰 등가파장 회절격자 간섭계

  • 황태준 (한국과학기술원 기계공학과 BUPE연구단) ;
  • 김승우 (한국과학기술원 기계공학과 BUPE연구단)
  • Published : 2004.02.01


We present a diffraction grating interferometer of large equivalent wavelength specially designed for flatness testing of rough surfaces. Two transmission diffraction gratings are illuminated on the object under test by use of two measurement beams with different angles of incidence, which yields a large equivalent wavelength. This interferometer design minimizes unnecessary diffraction rays and the systematic error caused by the diffraction gratings, and provides a large working distance and easy alignment. To improve the measurement accuracy, phase shifting technique is applied and the equivalent wavelength error caused by defocus is calibrated. Test results obtained from mirror surfaces and machined rough surfaces are discussed.


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