Abstract: An acousto-optic tunable filter configuration and a method for the operation thereof, whereby the tuning range is extended. A non-collinear acousto-optic tunable filter crystal has a first transducer bonded to one transducer face of the crystal and a single transducer bonded on the opposite crystal face which crystal face is cut so as to be parallel to the first transducer. The first transducer operates at a center frequency f.sub.1 and the second transducer operates at a center frequency f.sub.2. By launching acoustic waves having a center frequency f.sub.1 into the crystal from the crystal's first side acoustic waves propagate in a first direction such that the interaction of the acoustic wave with the light results in the absorption of a phonon. Acoustic waves having a center frequency f.sub.

Abstract: Disclosed is a method of maintaining the power of the output of a xenon chloride laser. The gases in the lasing chamber are circulated between the lasing chamber and a reforming chamber. In the reforming chamber, the gases are contacted with at least one metal chloride which is chemically less stable than hydrogen chloride. The temperature of the metal chloride in the reforming chamber is maintained between the condensation temperature of hydrogen chloride and the dissociation temperature of the metal chloride used. Also disclosed is apparatus for performing this method.

Abstract: The invention provides an apparatus for the detection of a selected species in a gas sample and includes a photo-acoustic detector coupled to an infrared radiation source with an acousto-optic tunable filter disposed between the source of infrared radiation and photo-acoustic detector. This combination is capable of measuring concentrations of controlled vapors in the parts-per-million range. These measurements may be performed in a few seconds via the portable gas detection and measurement device of this invention.

Abstract: A double sealed technique in an evacuated quartz jacket produces an electrical feedthrough assembly suitable for use in sealed-off, pulse, longitudinal discharge lasers compatible with operating temperatures of up to 1100.degree. C. without oxidation and with a minimum of circuit inductance.

Abstract: Shifted Raman radiation for an all-hot Raman discharge cell is produced by external laser pumping of a metal halide medium in the cell during an afterglow period following dissociation of the metal halide medium into metal atoms and before recombination to form the original species of the metal halide medium.

Abstract: Incandescent source of visible radiations comprises a refractory support member having a thin, refractory material layer thereover, with both the support and the thin layer adapted to be heated to high temperatures. The material comprising the thin layer is highly absorptive for visible radiations and thus is a correspondingly good emitter for such visible radiations, and the material comprising the thin layer is highly transmissive for infrared radiations and a correspondingly poor emitter for such infrared radiations. Minute optical discontinuities in the thin layer act to scatter infrared radiations and the infrared radiations which are generated in the support member are scattered back to the support member in order to contribute to the heating of same. Visible radiations, in contrast, are absorbed and emitted by the thin layer so that this layer is a very selective radiator.