An analogue contact probe using a compact 3D optical sensor for micro/nano coordinate measuring machines

This paper presents a new analogue contact probe based on a compact 3D optical sensor with high precision. The sensor comprises an autocollimator and a polarizing Michelson interferometer, which can detect two angles and one displacement of the plane mirror at the same time. In this probe system, a tungsten stylus with a ruby tip-ball is attached to a floating plate, which is supported by four V-shape leaf springs fixed to the outer case. When a contact force is applied to the tip, the leaf springs will experience elastic deformation and the plane mirror mounted on the floating plate will be displaced. The force-motion characteristics of this probe were investigated and optimum parameters were obtained with the constraint of allowable physical size of the probe. Simulation results show that the probe is uniform in 3D and its contacting force gradient is within 1 mN mu m(-1). Experimental results indicate that the probe has 1 nm resolution, +/- 10 mu m measuring range in X -Y plane, 10 mu m measuring range in Z direction and within 30 nm measuring standard deviation. The feasibility of the probe has been preliminarily verified by testing the flatness and step height of high precision gauge blocks.