Abstract: A method of combining beams from a plurality of laser resonators includes frequency modulating the output of each of the lasers with one or more of the lasers frequency modulated out-of-phase with the others. The frequency modulated beams are directed along parallel spaced-apart paths and overlap in a plane along the paths to form a combined beam having a flat-topped intensity distribution.

Abstract: The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Abstract: The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Abstract: An output beam from a laser is directed into an acousto-optic cell. The acousto-optic cell is driven by RF voltages at four different frequencies. A portion of the laser output beam is diffracted by the acousto-optic cell at four different angles to the laser output beam. This provides four secondary beams. The magnitude of the RF voltages applied to the acousto-optic cell and the power in the laser output beam may be cooperatively varied to provide a predetermined power in each of the secondary beams. The four secondary beams are directed into four beam separating optical fibers connected to four transport optical fibers for transporting the secondary beams to a location remote from the laser. Power in the beams is monitored at the output ends of the four optical fibers for controlling the magnitude of the RF voltages. All four beams are focused into the beam-separating fibers by a single lens.

Abstract: An improved laser system includes a sealed-off, RF excited, diffusion cooled, high pressure, short pulsed, high peak power waveguide and slab CO2 laser that avoids problems typically associated with obtaining a diffused discharge at high gas pressures, without arcing and without corona, while maintaining the unsaturated gain and gas temperature experienced at low pressures and scaling to higher pressures. Such a system has a long operating life-time, and is capable of operation at high gas pressures to obtain relative fast rise and fall time pulses. The system emits relatively short pulse widths, with pulse energies up to and exceeding 30 mJ, with reasonably high pulse repetition rates. The system also has a low pulsed RF power duty cycle, thereby enabling the generation of high peak power pulses, as well as reasonable average power and reasonably high peak powers.

Abstract: Through the use of a relatively inexpensive third mirror on a novel folded hybrid unstable resonator configuration, the optimum output coupling for a given laser design can be explored quickly and easily with a minimum of intracavity mirror alignment. No changes in either the radii of curvature of the three cavity optics or their spacing are required for this exploration. In addition to providing techniques for purposefully and systematically introducing mirror edge effects or avoiding edges effects altogether, the invention provides that output beams of different width can be advantageously explored in a relatively simple and straightforward manner. The invention provides that higher geometric magnification cavity designs may be made compatible with low diffraction output coupling in a configuration that uses only three totally reflecting optics.

Abstract: A portal for security screening of transport passengers includes a THz trans-receiver. In one example of the portal, the trans-receiver includes a small-spot, reflective scanning arrangement including a single detector in a heterodyne receiver configuration. In another example, the trans-receiver includes a large-beam reflective scanning arrangement with the trans-receiver in a synthetic aperture radar (SAR) configuration.

Abstract: A method for inspecting a package to identify an object concealed in the package includes passing two beams of THz-radiation through the package. The frequency of THz radiation in one beam is different from that in the other, and the beams are at an angle to each other. Each of the transmitted beams is used to form an image of the package and the object. The absorption coefficient of the object is determined from the two images. The material of the object is determined from the absorption coefficients at the two frequencies. The method is useful for detecting explosive material concealed in baggage.

Abstract: A thin film polarizer (TFP) and a half-wave CdTe electro-optical crystal are utilized to achieve a higher damage threshold in Q-switching CO2 lasers for material processing applications. Half-wave CdTe electro-optical modulators can be used without the arcing and corona problems typically associated with the higher drive voltage by placing low dielectric constant insulators (such as BeO) around the CdTe crystal. Doubling the voltage placed across a CdTe crystal enables the crystal to function as a half-wave phase retarder EO switch with the same dimensions as a crystal functioning as a quarter-wave EO modulator. These half-wave EO switches can be used with TFPs to shape the output pulses, as well as to direct alternate pulses of repetitively pulsed super pulsed slab lasers to alternate scanners, thereby doubling the output of laser hole drilling systems.

Abstract: A laser output beam is directed into an acousto-optic cell. The acousto-optic cell is driven by RF voltages at a plurality of different frequencies. Portions of the laser output beam are diffracted by the acousto-optic cell at a plurality of different angles corresponding the different drive frequencies. The different portions of the output beam define a plurality of secondary beams. The magnitude of the RF voltages applied to the acousto-optic cell and the power in the laser output beam may be cooperatively varied to provide a predetermined power in each of the secondary beams.

Abstract: A laser includes an external modulation device including two spaced-apart wire-grids. The device has a reflectivity peak at a wavelength dependent on the spacing between the wire grids. The device is arranged to reflect and transmit radiation received from the laser. The reflected and transmitted radiation are modulated by varying the spacing between the wire-grid polarizers. The device may be used as an end mirror or a fold mirror of a laser resonator and operated as a Q-switch for the laser resonator. Q-switching is accomplished by varying the reflectivity of the device at the lasing wavelength from below to above a threshold reflectivity value for lasing.

Abstract: A communications transmission system and method modulates a radiation source at higher rates for either fiber optic telecommunication systems or for digital electrical or optical switches associated with computer routers or servers. A first source provides a carrier signal; a modulator receives the carrier signal and an information signal to generate a modulated carrier signal. A second source provides a transmission signal; and a signal mixer receives the modulated carrier signal and the transmission signal to generate a frequency shifted transmission signal. The transmission system increases the amount of analog or digital information that can be transmitted over a communications network. The modulated carrier signal and the frequency shifted transmission signal may be filtered.

Abstract: A communications transmission system which modulates a radiation source at higher rates for either fiber optic telecommunication systems or for digital electrical or optical switches associated with computer routers or servers is presented. The transmission system increases the amount of analog or digital information that can be transmitted over a communications network. The system comprises a first source for providing a carrier signal; a modulator receptive of the carrier signal and an information signal to generate thereby a modulated carrier signal; a second source for providing a transmission signal; and a signal mixer receptive of the modulated carrier signal and the transmission signal to generate a frequency shifted transmission signal.

Abstract: A clamping device for an RF excited laser is provided which reduces stress on ceramic components and also is less expensive than existing clamping devices. The RF excited laser lacking an electrode over the waveguide channel intersection regions. Ceramic covers are provided over a portion of these channel intersection regions to reduce plasma build up. Increased power is achieved by adding a fourth channel to a conventional waveguide to form a ring resonator. The optical component mount uses radial compressive forces to hold the optical component to a post, thereby preventing the face of the optical component from being distorted. Mirror mounts are also configured to allow more mirrors to be mounted at each end of the laser. The waveguide channel of the RF excited laser having a U-shaped cross section and an aspect ratio grater than one-to-one, which improves laser performance. A beam redirection device allows the laser head to serve as a mounting surface for other optical components.

Abstract: The present invention is a system for controlling the power level of a beam exiting an acousto-optic cell and/or a beam delivery device. A beam detector senses the power level of the beam and produces a power signal indicative thereof. An error detector compares the power signal to a predetermined power level. If the power signal and predetermined power level differ, the error amplifier emits a correction signal to a variable amplitude source, which adjusts the amplitude of the acoustic drive frequency such that the power level of the beam exiting the acousto-optic cell and/or the beam delivery device is substantially equal to the predetermined power level.