Fundamental study of surface topography measurement by broadband optical frequency comb scattering spectroscopy - Basic study of diffraction pattern spectroscopy by VIPA Spectrometer –

Abstract

Recently, high-precision and in-process surface topography measurement methods are required in the field of precision machining. Laser inverse scattering has been reported as a method satisfying these characteristics. However, the dynamic range and spatial resolution of this method depend on the wavelength of the light source, which limits the surface topography that can be measured when using a single-wavelength light source. This limitation can be removed by using multi-wavelength laser. When a multi-wavelength laser is used as a light source, a method to spectrally disperse surface image of the sample and Fraunhofer diffraction pattern is necessary.In this paper, we propose a method for spectroscopy of surface image and diffraction pattern using VIPA spectroscopy. Then, the diffraction pattern using the optical frequency comb as a light source was spectrally analyzed with the proposed method and it was confirmed that the diffraction pattern of each wavelength can be measured.

Keywords

• Laser inverse scattering
• Surface topography measurement
• Optical frequency comb
• VIPA spectroscopy