Zygo Corporation

Apre Instruments, Inc.

Robert Smythe

Peter J De Groot

Leslie Ludwig Deck

Artur Olszak

Piotr Szwaykowski

James F Biegen

Donald S Battistoni

A non-contact optical probe utilizes an optical reference surface that projects a curved test wavefront toward the test surface and detects it by creating curved interferometric fringes localized in space in front of the reference surface. When a point to be measured on the test surface intersects the location of the fringes, the condition is detected by the probe. Because the fringes are localized at a known position in space with respect to a reference system, the precise coordinate of the surface point can be established. Such localized fringes are preferably produced by a spectrally controllable light source. The curvature of the fringes ensures a sufficiently large angle of acceptance for the probe to capture light reflected from points of high surface slope. The probe is particularly suitable for coordinate measurement machines.

Interferometric non-contact optical probe and measurement

Apparatus and methods for generating an empirically determined mathematical model of wavefront error in an interferometer as a function of aperture misalignment and then applying the model to correct subsequent measurements. The methods are useful in Fizeau and other types of interferometers in which carrier fringe analysis may be used for reducing errors caused by environmental and vibration effects.

Method for calibration and removal of wavefront errors

Apparatus and means for calibrating optical gap-measuring instruments, including a preferred calibration standard (100) comprised of a substantially flat, transparent element (10) held in contact with the convex spherical surface (25) of a substantially opaque element (20) to provide an obvious and unambiguous region over which the gap is zero. The optical gap measuring tool that is to be calibrated is oriented so as to illuminate the interface. The calibration standard (100) is translated in position with respect the gap measuring tool in such a way as to vary the measured gap, while at the same time data storage means record the gap measurement as a function of relative position. This data is then compared to the predicted variation from the geometry of the calibration standard (100). Provided that the elements (10, 20) are of high optical quality, deviations of the measured data from an ideal parabolic curve are indicative of calibration errors.

Calibration standard for optical gap measuring tools

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Middletown, CT, United States of America

Robert Smythe