Dynetics, Inc.

Robert J Berinato

Christopher Scott Anderson

Michael C Zari

Anthony F Zwilling

James M Stanfield

Larry M Foster

W Neil Mohon

Joseph F Fikes

Franklin H Perkins

A scanner and a method for scanning a beam along a path employs a housing tint defines a first cylindrical cavity. A ring gear is disposed within the cylindrical cavity and affixed to the housing. A beam is generated from a fixed location relative to the housing. A drive disk is disposed within the first cylindrical cavity. The drive disk defines a second cylindrical cavity and has a first axis of rotation. The drive disk defines a first channel in communication with the beam. The first channel has a first proximal end pivotally rotatable about an axis adjacent the fixed location. A scan disk is disposed within the second cylindrical cavity and has a second axis of rotation offset from the first axis of rotation. The scan disk defines a second channel. The second channel has a second proximal end in communication with the first distal opening. The second proximal end pivotally rotates about an axis adjacent the first distal end. A ring motor causes the drive disk to rotate about the first axis in a first direction. A spur gear, affixed to the scan disk, engages the ring gear so that as the drive disk rotates in the first direction, the spur gear is displaced along the ring gear thus causing the scan disk to rotate in a second direction opposite the first direction causing the second distal end to reciprocate. The beam is coupled through the first channel and the second channel and out of the second distal opening toward the path, thereby causing the beam to scan along the path as the second distal end reciprocates.

Counter-rotating scanner

An acousto-optic apparatus is described that varies the time delay of electrical signals over a continuum of delays. In the preferred embodiment, a light source, which can be either coherent or incoherent, emits an optical beam that is focused into an acousto-optic cell. An input electrical signal is used to drive the acousto-optic cell which, in turn, modulates the focused optical beam. Portions of the input optical beam are modulated and diffracted at angles proportional to the frequencies and phases contained in the input electrical signal. By appropriately choosing the cone of angles at which the light is focused into the acousto-optic cell, the diffracted optical beam can be made to overlap with portions of the undiffracted, unmodulated optical beam. All of the light exiting the acousto-optic cell is then collected onto a device for detection. Optical photomixing of the diffracted beam and the undiffracted beam is performed in order to derive the input electrical signal with a time delay. The approach to generating a continuously variable delay maintains a true time delay of the input electrical signal on its electrical carrier frequency, and does not suffer the limitations imposed by only time delaying the modulation envelope of the input electrical signal. Since all optical beams travel exactly the same physical path, the present invention is robust to mechanical or thermal variations unlike inferior acousto-optic approaches for implementing time delay.

Continuously variable delay lines

An acousto-optic correlator for wideband signals. The invention is defined by and relates to device in which a laser beam is split into two paths of a Mach-Zehnder interferometer arrangement. A first Bragg cell of which, modulated with a signal Re{S.sub.1 (t)exp(jw.sub.o t)}, receives the first beam that is reflected off a first flat mirror. A second Bragg cell of which, modulated with a signal Re{S.sub.2 (t)exp(jw.sub.o t)}, receives a beam that is reflected off a second flat mirror. The undiffracted light from both of the modulators is blocked. The diffracted light emitted from the first and second Bragg cells passes through first and second imaging lenses respectively. The two diffracted light beams are then combined with an angular separation between beams. The combined beam is incident upon a square-law detector array which is at the image plane of the imaging lenses. Due to the square-law detection process, terms of low frequency biases and complex correlation on a spatial carrier develop. This output is filtered to remove the low frequency component. The remaining signal being demodulated by in-phase and quadrature detection techniques. The correlation magnitude and the phase are calculated. This provides for precise temporal resolution.

Acousto-optic time-integrating signal processor

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Huntsville, AL, United States of America

Robert J Berinato