Abstract: A new method for improving the mechanical properties and nonlinear optical performance characteristics of gallium selenide crystals (GaSe) is disclosed. A charge of GaSe crystals was doped with indium before being made into a crystal. The indium-doped GaSe crystals have improved physical properties in that they can be cut along the cleave planes and the cleaved surfaces polished without the usual delaminations typically observed in prior art pure GaSe crystals. The indium-doped crystals were tested in a second harmonic generation (SHG) system and found to have nearly twice the SHG efficiency as pure, or undoped, GaSe crystals.

Abstract: An acousto-optic tunable filter (AOTF) has one or more optical wavelength passbands dependent on the frequency or frequencies of a radio frequency signal applied thereto. A radio frequency generator applies the radio frequency signal under computer control of the RF frequency so that the radio frequency signal has one or more preselected frequency components. An input optics system directs incident object or scene light to the AOTF. A first polarizing element passes to the AOTF only image light which is polarized in a first direction. A second polarizing element receives output image light from the AOTF and passes only image light which is polarized in a direction orthogonal to the first direction. The image light passed by the second polarizing element is detected by a camera. An output optics system focusses image light passed by the second polarizer on an image plane of the camera, and an image corresponding to the detected image light is recorded.

Abstract: An infrared laser energy generating apparatus, specifically a transverse excited atmospheric (TEA) laser generating apparatus incorporating a low pressure gain cell and tunable reflecting means to eliminate mode-beating and gain-spiking of the laser beam, to select a given lasing transition, and to accomplish this selection and filtering of a high power, large diameter laser beam using smaller diameter optical components.

Abstract: Multiple wavelengths are produced from a single laser gain medium by utilizing gain saturation effects within the laser cavity. Two or more partially reflecting mirrors are coupled to a totally reflecting mirror through the laser gain medium by a grating element. The optical path lengths defined by each of the partially reflecting mirrors are varied by the positioning of the partially reflecting mirrors. This permits a lower gain line to build up first, followed by a higher gain line, which then terminates the lower gain line through gain saturation. The frequency switching times and pulse intensities of the wavelengths can be varied by varying the optical path lengths.