Abstract: The crystal is solid CdTe or GaAs for modulating a laser beam. The mount comprises Al.sub.2 O.sub.3 or BeO ceramic between the crystal and a U-shaped aluminum housing on three sides to provide low stray capacitance and high thermal conductivity to the cooled housing. A layer of lead between the ceramic and the housing enhances the acoustic damping of the structure. Electrodes are attached to the crystal, with lead used to enhance dissipation of acoustic energy. in contacting flexible tabs on the electrodes with terminals no pressure or stress is transmitted to the crystal, thereby eliminating a problem of stress-induced birefringence.

Abstract: The apparatus is part of an optical radar set and comprises a high powered O.sub.2 pulsed transmitter laser which is injection controlled to operate at a fixed frequency offset from a lower powered CO.sub.2 local oscillator laser. A portion of the output of the local oscillator laser is applied to an acousto-optic Bragg cell, together with an RF signal equal to the desired intermediate frequency of the radar set. The upshifted first order output of the Bragg cell is injected into the transmitter laser for stabilization purposes. This results in a stable intermediate frequency for the optical radar set.

Abstract: A frequency control system for a laser for compensating for thermally-induced laser resonator length changes. The frequency control loop comprises a frequency reference for producing an error signal and electrical means to move a length-controlling transducer in response thereto. The transducer has one of the laser mirrors attached thereto. The effective travel of the transducer is multiplied severalfold by circuitry for sensing when the transducer is running out of extension and in response thereto rapidly moving the transducer and its attached mirror toward its midrange position.

Abstract: This multi-format modulated laser may be programmed to produce a variety of utput waveforms by applying a different one of a plurality of modulating waveforms thereto. The outputs can include continuous waves, both modulated and unmodulated, Q-switched pulses, cavity dumped pulses, shaped pulses and mode locked pulses. The laser is provided with an intracavity electro-optic modulator and may comprise two coupled cavities with a gain cell in one cavity and the modulator in the other cavity.

Abstract: A passively Q-switched laser system uses a common Q-switch cell to control two lasers. The first laser to turn on Q-switches the other laser.

Abstract: The intracavity modulated laser includes a main cavity and an adjacent coed cavity with a gain cell in the main cavity and an electro-optic modulator in the coupled cavity, the cavities being coupled in such a way that the energy level in the coupled cavity during laser operation is much lower than that in the main cavity, and whereby the modulator can selectively affect the polarization of energy in accordance with a voltage applied thereto to selectively couple energy out of both cavities in a desired manner.

Abstract: A scanning and/or tracking mechanism for use in airborne obstacle avoidance ptical radars operating in the infrared region. The radar beam is scanned by passing it through a pair of in-line rotating optical wedges which rotate around the boresight axis and which are transparent to the infrared radiation. The wedges are separately driven by servo systems including hollow shaft torque motors with the wedges mounted in the hollow shafts thereof. A high resolution and low backlash shaft position encoder is utilized comprising encoding discs directly driven by the optical wedges and including a novel decoding system.

Abstract: A passively Q-switched laser system uses a common Q-switch cell to control two lasers. The first laser to turn on Q-switches the other laser.

Abstract: An RF-discharge waveguide laser incorporates two or more waveguides sharing a common set of discharge electrodes. The device may be used to provide two lasers operating on the same or different frequencies, or a single laser with two waveguides contributing to the power output.

Abstract: A homodyne laser of a first frequency is conically scanned on a surface from an elevated position and the beam is scattered by the surface. A return beam is formed from this scattered beam and is mixed with a single side band suppressed carrier laser beam at an offset frequency, producing an electrical signal whose frequency shifts from the offset frequency in proportion to the velocity relative to the surface. That shift is a function of the scan position and the direction of movement. Velocity components of the signal reflecting drift velocity and heading velocity are resolved from this signal by referencing it to the scan position at drift and heading positions. The signal component reflecting elevation velocity is resolved by removing those scan dependent components.

Abstract: A laser radar system and method for tracking speckle generated by the interaction of a beam of coherent electromagnetic radiation with a target to enhance the signal to noise ratio of a return signal is disclosed. The radar system is formed with a transceiver having a common transmit/receive optical path including beam steering mirrors capable of impressing a conical scan on a transmitted and received beam, a heterodyne circuit capable of sensing the position of a speckle maximum within the aperture of the transceiver, a peak detector capable of processing the output of the heterodyne circuit, a phase sensitive detector capable of producing a two axis discriminate proportional to the offset error of the speckle maximum and a transceiver control responsive to the two axis discriminate to provide transceiver pointing to maintain the speckle maximum within the aperture.

Abstract: A sensor for measuring the flux of a gas and some simple alternate embodiments are disclosed. The sensor employs charged particle techniques and includes provision for compensating for environmentally produced changes in the charged particle source. The basic device includes an active region containing the charged particle source located between two upstream charged particle collectors and two downstream charged particle collectors, means for maintaining suitable electric fields between the charged particle source and the collectors, and means for measuring the electric current flowing in each collector. In operation, the sensor is able to compensate for changes in the charged particle source characteristics which would otherwise result in a change of sensor calibration.

Abstract: The beam of a laser radar is moved over the field of view by means of a p of scanner/trackers arranged in cascade along the laser beam. One of the scanner/trackers operates at high speed, with high resolution and a narrow field and is located in the demagnified portion of the laser beam. The other scanner/tracker operates at low speed with low resolution and a wide field and is located in the magnified portion of the laser beam. The two scanner/trackers complement each other to achieve high speed, high resolution scanning as well as tracking of moving targets. A beam steering telescope for an airborne laser radar which incorporates the novel dual mode scanner/tracker is also shown.