Laser profiling system for on-line measurement of superfine surfaces

A profiling system for on-line and noncontact measurement of superfine surfaces is described. The system uses the principle of a differential interferometer with coaxial interference arms. The measuring head (optical part) of this system is separable and can be installed on machine tools or in existing measuring instruments. It has excellent resistance to vibration and air turbulence; therefore it needs no damper or cover. This system scans sample surfaces to measure a microprofile with a vertical resolution of 0.08 nm rms.