Alexander Stein

Efficient tunable H2 Raman laser

We have obtained 85% quantum conversion by stimulated rotational Raman scattering of CO2 laser radiation in para H2. An output energy in excess of 1 J and a peak power of ∼20 MW was measured at 623 cm−1. The prelimininary measurements suggest that the temporal and spatial coherence of the generated Stokes wave are close to the ideal theoretical limitation.

Controllable pulse compression in a multiple-pass-cell Raman laser

Pulse compression has been observed with the 16-microm multiple-pass-cell hydrogen Raman laser. The effect, which also leads to high quantum conversion of the pump radiation, has been analyzed and is a result of beam crossings inherent in the geometry of the device.

Stimulated rotational Raman scattering from para-H 2 pumped by a CO 2 TEA laser

We have observed stimulated rotational Raman scattering (SRRS) from para-H(2) pumped by a CO(2) TEA laser operating on the strong P- and R-branch transitions of both the 9.4- and 10.6-microm bands. Small signal gain for the Stokes wave in excess of 80 dB has been obtained for TEM(00) pump powers of 8.5 MW in a multiple-pass gain cell cooled to liquid-nitrogen temperatures.

Radiance enhancement of the 16-μm CF 4 laser

The spectral radiance and quantum yield of the CF/sub 4/ laser operating at 16 ..mu..m have been increased more than an order of magnitude by narrowing the frequency bandwidth of the CO/sub 2/ pump laser and by telescopically mathcing the pump radiation to the lowest-order mode of the 16..mu..m resonator. The temporal and spectral characteristics of the radiation, as well as the optical gain of the laser, have been determined.

Infrared multiphoton dissociation of UF6

Abstract Infrared multiphoton dissociation of UF 6 has been demonstrated with a 16μm CF 4 laser. The process has been detected by Mie scattering from dissociated particulates and by infrared fluorescence from the HF produced in the exothermic reaction of one of the dissociation products, fluorine, with added hydrogen buffer gas. A threshold and dissociation yield similar to that reported for SF 6 has been found.

Carbon dioxide laser monitor for NH 3 in flue gas

An instrument was developed for the detection of NH3 in flue gas, exploiting a fortuitous spectral overlap between the ν2aQ(6,6) absorption line of NH3 and the R (18) emission line of the isotopic 13C16O2 laser. The system was developed for use with De–NOx processes, which convert harmful nitric oxides generated in utility and industrial furnaces into harmless nitrogen and water vapor by injection of NH3. The instrument detects unreacted NH3 in the flue gas down to concentrations of a few ppm with an accuracy of ∼10%. It can serve as an environmental monitor and as part of a feedback control system to adjust the upstream NH3 injection to the desired rate.

Heterodyne pyrometry in furnaces.

A new procedure for determining the temperature of flue gas inside a large industrial furnace is considered. The hot furnace wall is used as a background of arbitrary radiance. (AIP)