レーザ干渉計を搭載した高精度表面粗さ測定機の開発

Abstract

Surface texture is one of the important standards for the industry. National Measurement Institute of Japan (NMIJ) currently provides surface texture calibration services. In this study, the authors developed a new instrument for traceable measurement of surface texture equipped with laser interferometer.The new surface texture measuring instrument directly measures displacement of stylus by using laser interferometer in order to make surface texture measurement traceable to the national standards. Measurement path of laser interferometer is kept in vacuum to eliminate effects of air fluctuation and stabilize measurement conditions. The main frame of the surface texture measuring instrument is made of ceramics and glass ceramics to protect the instrument from thermal effects. A calibration item is measured as a movable stage of this instrument moves along the horizontal plane. To validate calibration capability, the groove depth standard and the roughness standard were measured with both the new surface texture measuring instrument and the NMIJ's conventional calibration system, and the two measurement results were compared with each other. Uncertainties of depth and roughness measurements taken with the new surface texture measuring instrument are found smaller than those of the NMIJ's conventional system, which demonstrates calibration capability of the new surface texture measuring instrument.