Precision measurement of micro-lens profile by using a force-controlled diamond cutting tool on an ultra-precision lathe

Abstract

This paper describes surface profile measurement of micro-lenses cut on a cylinder workpiece by a force sensor integrated fast tool control unit (FS-FTC), which consists of a single point diamond cutting tool, a PZT actuator to move the tool, a capacitive displacement sensor to measure the tool displacement, and a piezoelectric force sensor to detect the cutting force along the in-feed direction. After the fabrication, the cutting tool is then employed as a stylus probe for measurement of the micro-lens profile, without removing the workpiece and the cutting tool from the ultra-precision lathe. During the surface profile measurement, the contact force between the cutting tool edge and the micro-lens surface, which is detected by the force sensor of the FS-FTC, is kept constant by servo control of the tool position with the PZT actuator when the scanning motions are generated by the spindle and the slide of the ultra-precision lathe. The measurement principle and measurement results are presented.