Abstract
A high resolution optical non-contact sensor for surface roughness has been developed. The principle of the sensor is based on astigmatic focus error detection which has been employed in the pick-up for optical disk player. At first the measuring principle of the method, basic analysis for obtaining a guiding principle of the design and optical system arrangement have been described. Then the results obtained by this method have been compared with that obtained by precise diamond stylus method on several different types of surfaces. The light source of the newly developed apparatus is a diode laser which has output power of 2 mW and wave length 790 nm. The object lens of the sensor is a standard microscope objective and it can be interchageable with other objectives. The size of the sensor is small enough for using on-machine condition. The sensor has demonstrated sensitivities of the order of nanometers on diamond turned metal mirrors. It also permits on-machine measurement of surface profiles in the condition where the object surface is mounted on a machine tool.
