Wyko, Inc.

Erik L Novak

Chiayu Ai

A broad-bandwidth interferometric system that produces irradiance signals at multiple vertical-scanning positions as a function of optical path differences between a test and a reference surface. The effective peak of the envelope defined by the modulation component of the irradiance signal is estimated by finding the scanning position corresponding to the centroid of a function substantially equal to the square of the first-order derivative of the measured irradiance. The surface height at each pixel is determined directly from digital irradiance signals, thereby greatly reducing the data-processing steps and associated costs taught by the prior art and correspondingly simplifying the hardware requirements of the system for rapid on-line display of height measurements. The approach is free of the ambiguities inherent in multi-peak modulation functions, thereby producing surface maps with reduced artifacts. This improved technique produces results otherwise comparable with those obtained by standard techniques and requires no dedicated hardware for rapid on-line applications.

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Tucson, AZ, United States of America

Erik L Novak