Veeco Instruments Inc.

Wyko, Inc.

Robert E Knowlden

David J Aziz

Matthew P Abbene

A pulsed light source in used conjunction with a ramping scanning mechanism for phase-shift and vertical-scanning interferometry. The pulse length and the scanning velocity are selected such that a minimal change in OPD occurs during the pulse. As long as the duration of the pulse is shorter than the detector's integration time, the effective integration time and the corresponding phase shift are determined by the length of the pulse, rather than the detector's characteristics. The resulting minimal phase shift produces negligible loss of fringe modulation, thereby greatly improving signal utilization during phase-shifting and vertical-scanning interferometry.

Pulsed source scanning interferometer

Structural components are added to an interferometric objective to offset the effects of temperature variations. The components are mounted between the sleeve housing the optics of the objective and the collar housing the optics of the interferometer. Each component is coupled sequentially, such that the thermal response of the assembly is substantially the linear combination of the response of each component and is designed to cause a shift in the opposite direction to the shift produced by a temperature change in the unmodified device. The thermal characteristics and dimensions of the components are chosen empirically to provide a minimum shift between the reference mirror and focal point in the interferometric objective as a function of temperature.

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Tucson, AZ, United States of America

Robert E Knowlden