US Government As Represented by the Secretary of the Army

Exotech Limited

Weiser, Sidney

Sidney Weiser

A specific small area of a crystal sample is scanned by a laser beam which rotates about an axis substantially perpendicular to the sample surface such that the intersection of the beam with a plane above and parallel to the surface describes a true spiral or a stepwise spiral pattern. The laser beam is reflected different amounts for different beam positions to produce a reflectance pattern indicative of crystallographic orientation.

Method of and apparatus for real-time crystallographic axis orientation

The invention is an apparatus for determining the quality of optical equipment through measurement of the modulation transfer function of the equipment. The apparatus includes an elongated, opaque sheet member or reticle, uniformly curved about an axis substantially perpendicular to the longitudinal centerline thereof, which has a data pattern comprising at least one bar pattern of discrete spatial frequency positioned longitudinally thereon. Each of the data patterns has optical transmission characteristics that vary periodically along its length according to a predetermined spatial frequency distribution. A rotatable mirror with its axis of rotation coincident with the center of curvature of the reticle is mounted so that it reflects an incident image onto the stationary reticle. An illuminated image producing source projects a slit image through optical equipment whose quality is to be determined to produce a spread function response of the optical equipment and the response is projected onto the rotatable mirror. The mirror is rotated to cause the spread function response to be reflected therefrom and sweep the data pattern so that the light transmitted through the data pattern is modulated by the interaction of the data pattern with the spread function response. The intensity of the transmitted, modulated light from the slit image is converted into an electrical data signal and the amplitude of the fundamental frequency components of the electrical data signal is determined. These measurements determine the modulation transfer function of the optical equipment under test.

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Silver Spring, MD, United States of America

Sidney Weiser