Frank C. Demarest

High-resolution, high-speed, low data age uncertainty, heterodyne displacement measuring interferometer electronics

An advanced displacement measuring interferometer system has been developed to satisfy the needs of semiconductor manufacturing and lithography. The system electronics provides a position resolution of 0.31 nm at velocities up to 2.1 m when the system is used with a double-pass interferometer. Output data rates up to samples per second are available. The data age, which is the delay from the interferometer optics to the measurement sample, can be adjusted to equalize differences between axes to within 1 ns. This low data age uncertainty is necessary for high-resolution, high-speed, multiple-axis measurements.

Laser Doppler velocimeter for velocity and length measurements of moving surfaces.

An industrial laser Doppler velocimeter has been developed for accurately measuring the velocity and length of moving surfaces. The instrument’s advanced optical and electronic design provides a large depth of field, high SNR, and large dynamic range making it very suitable to industrial process control applications.