Determination of Sampling Distance for Areal Surface Form Measurement using Electric Capacitance Displacement Sensor

Abstract

This paper describes the method of determining the sampling distance using electric capacitance type of displacement sensor for areal surface form measurement. Amplitude transmission characteristic of the sensor was disclosed and analytical simulation was carried out. Its inconvenient sensor output signal was functionally compensated with Spline low pass filter. From the sampling condition for the Spline filtration, the necessary minimum sampling distance was determined while the maximum sampling distance was introduced from auto-correlation curve of filtered profile. Macroscopically similar surface profiles were obtained at the sampling distances determined by the two methods.