Wyko, Inc.

4d Technology Corporation

Larry Denneau, Jr

James E Millerd

Neal Brock

A multi-channel imaging system is calibrated by measuring the geometric distortion in each sub-image, generating corresponding correction factors, and applying such factors to correct subsequent image data. In addition, intensity transfer-function arrays are measured at each pixel, and further used to correct for system and detector nonlinearities and nonuniformity between images. The procedure is repeated over a range of wavelengths to produce a complete set of correction coefficients and transfer functions. When the system is used for interferometric phase measurements, multiple measurements are preferably taken and a random phase offset in the reference path length is introduced at each measurement. The multiple phase data so derived are then averaged to reduce phase-dependent systematic measurement errors.

Calibration and error correction in multi-channel imaging

A method for correcting a height map produced by an optical height profiler while scanning a target surface. Regions of bad data are identified and erroneous height values are replaced with provisional height values based selected from neighboring valid height values. Each provisional height value is also assigned a position index corresponding to its proximity to the boundary of the region. Starting from the interior of the region, the technique then replaces each provisional height value with a corrected height value calculated by interpolation of valid height values as a function of distance from the boundary as represented by the position indices. The resulting corrected height map is suitable for on-line visual display.

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Tucson, AZ, United States of America

Larry Denneau, Jr