Abstract
For the on-machine roughness measurement it is desirable that the sensor is not easily affected by circumferential noise and datum errors due to the scanning motion. An optical stylus with an optical skid made by a new design concept is proposed to satisfy these necessities. In the developed sensor, a set of an optical source and an adjusting lens is added simply to the optical system of the usual critical angle type optical stylus. The optical beam from the added source is arranged to make another diplacement-sensitive range which is known as the wide range in the stylus of this type. The spot at the wide range is so large that it can smooth the profile of high spatial frequency components to serve for the optical skid. Influence of the thermal drift and other circumferential noises in the optical stylus is reduced to about 1/10 in the difference between the stylus and the skid. Profiles of ground surfaces are smoothed to almost flat planes in the output of the optical skid. Thus the developed sensor is confirmed to be very promising for the application to roughness measurements under on-machine or in-process conditions.
