Abstract: In one aspect, frequency fluctuations are stabilized in a laser beam using a frequency stabilization stage that includes a modulator for dithering (i.e., periodically scanning) the frequency of the laser beam, and absorption resonance cell that has a resonance at a predetermined linewidth to which the dithered beam is applied. The output of the cell is synchronously demodulated with respect to the dithering to produce a correction signal that represents the frequency fluctuations with respect to a reference frequency within the absorption linewidth, and the correction signal is used in a configuration which corrects for the frequency fluctuations and produces from the stage a non-dithered, frequency stabilized output. In another aspect, the frequency of the laser beam is controlled using the molecular or atomic resonances of a plurality of successive frequency stabilization stages.

Abstract: A coherent laser radar system in which a number of individual receiver modules are deployed in an area relatively near the targets to receive signals originating at a transmitter located at a much greater distance from the target area. The radar is particularly adapted for the midcource detection and tracking of missiles in space and differentiating between reentry vehicles and decoys. This permits a number of receivers to be positioned at separate points, each capable of receiving and analyzing reflected signals originating from a single transmitter. Direct communication between the transmitter and each receiver permits the transmitter to know at all times the location, velocity and direction of each receiver thus permitting the receivers to be positioned near the targets relative to the position of the transmitter.

Abstract: A pulsed gas laser having two spaced optical resonators each associated with a pair of high voltage electrodes. The first and second pairs of electrodes are positioned within a common plasma chamber including means for circulating a laser gas successively between the two pairs of electrodes. A common heat exchanger removes the heat energy from the two regions of plasma excitation. A high voltage pulse generator connected to the electrodes includes timing means for delaying the application of high voltage pulses to the second pair of electrodes, the delay being either (a) less than the time required for an acoustic shock wave to travel through the lasing gas from the first to the second pair of electrodes or (b) longer than the time required for the shock wave created by the discharge of the first pair of electrodes to die out. Each optical resonator is provided with an adjustable mirror arranged to reflect laser pulses to and from a mirror grating.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from an injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiment, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHz. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a difference frequency in the microwave range, say, above 5,000 MHz. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from a injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiment, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHz. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a different frequency in the micorwave range, say, above 5,000 MHz. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: The invention is described as embodied in a plasma chamber for use in gas lasers. A sealed nitrogen gas laser is provided with a pair of capacitance coupled, symmetrically positioned pre-ionizer elements in the form of a pair of insulated wire loops extending from one electrode to the region adjacent the other electrode. All parts of the plasma chamber accessible to ultraviolet radiation or ionized gases and are formed entirely of inorganic materials, such as ceramic and quartz, eliminating previously unrecognized difficulties resulting from the use of plastic or other organic materials in the chamber construction, thus making possible a sealed low-power nitrogen laser having a relatively long life.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from an injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiement, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHZ. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a difference frequency in the microwave range, say, above 5,000 MHZ. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: A gas laser is provided in which a replaceable module, comprising a plasma chamber and the associated high voltage components and circuitry, can be quickly and easily replaced by relatively unskilled personnel without any need for optical realignment. Each high voltage electrode of the plasma chamber includes a connector plate that extends through the envelope and engages a support plate of the module containing the high voltage pulse circuitry. These support plates are precisely positioned with respect to two resonator mirrors mounted permanently on a base structure, while the connector plates are precisely positioned with respect to the electrodes and windows of the plasma chamber. The positioning of the connector plates with respect to the electrodes, the windows and the optical axis is identical for each of the replaceable modules.

Abstract: A sensing system for the detection of trace gases in the atmosphere or contaminates on a surface. Particular chemical substances are detected at remote points by placing a sensor unit in the vicinity of the area to be examined and illuminating the area with a laser beam generated by the sensor unit. An optical detector, also carried by the sensor unit, registers the fluorescence produced by the substance illuminated and relays this information by a telemetry link back to the base site. The utility of the system is broadened by providing a chemical reactant selected to react with the substance to be detected to produce a reaction product that fluoresces strongly at the wavelength of the laser light. The chemical reactant is carried by the sensor unit and is sprayed into the area to be examined.

Abstract: A gas laser having an outer conductive shell and two axially displaced spaced plastic cylinders mounted within the shell. The inner plastic cylinder supports the high voltage components to produce a transverse electrical discharge. The outer plastic cylinder is spaced from the outer shell by rubber feet and forms an acoustic baffle to decrease the noise radiated during operation. High speed fans circulate the laser gas around the annular path between the two cylinders and between the high voltage electrodes. The inner plastic cylinder is manually removable for repair or other reason and carries with it all of the electrical components within the outer shell. High voltage is fed to the high voltage electrodes by means of a circuit that does not include the outer shell. This arrangement minimizes operating noise, provides maximum safety for operating personnel, and minimizes electrical interference.

Abstract: A pulsed laser system capable of producing pulses of radiation at relatively high peak power at a single resonator mode, said system comprisinga master laser oscillator capable of producing a beam of radiation at a desired frequency to be introduced to a power laser,a radiation-responsive pulsed power laser oscillator including an optical resonator formed by a set of reflectors, said laser adapted to receive periodic application of a voltage pulse, said optical resonator arranged to receive said introduced beam at least during the periodic application of said voltage pulse to said power laser whereby the frequency of radiation emitted by said power laser can be determined by the frequency of said introduced beam,monitoring means acting between pulses of said power laser to optically monitor the resonator cavity of said power laser to determine the frequency of the resonator mode of said power laser and produce a signal dependent upon said frequency,and stabilizing means responsive to said signal of said monit