Optical profilometer: a new method for high sensitivity and wide dynamic range

The noncontact optical measuring method is based on the focusing properties of simple optical elements. High sensitivity is achieved by the utilization of differential detection and electronic feedback systems. Preliminary measurements indicate that height sensitivities of the order of 0.1 microm with spatial resolution of better than 2 microm are easily obtained, while measurements in the millimeter range are also feasible. For optimization purposes, a mathematical analysis has been performed using operator algebra and the characteristics of the Wigner distribution function.