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Photodissociation of TlBr and CsBr by the 1850-Å mercury resonance line could lead to laser transitions at 5350 Å and 2.93 μ in Tl and Cs, respectively. The transition probabilities of Cs are such that radiative decay will maintain a population inversion between the 7^2P_3/2 and 7^2S_½ levels. Calculations indicate that a gain of 4% per m is expected at a temperature of 890° for photodissociation into the 7^2P_3/2, ½ Cs levels. In Tl, however, the 6^2P_3/2 level is metastable. A suitable quenching gas must be found before oscillation is possible at 5350 Å from photodissociation into the 7^2S_½ level. Nitrogen and CO_2 have been tried thus far without success.

Reliable estimates of alkali vapor densities in the absorption cells used in optical pumping experiments have usually been quite difficult to obtain. In the present work, a pressure-scanned Fabry–Perot etalon has been used as a high-resolution device to obtain absorption profiles from which the alkali vapor density can be directly derived. The measurements have been made with sodium only, and the results of these experiments are graphs of the optical-pumping signal strength in a Dehmelt transmission arrangement as a function of the alkali vapor density. These graphs may be useful in estimating vapor densities in those optical-pumping experiments for which construction of the requisite spectroscopic equipment is not feasible.

Reliable estimates of alkali vapor densities in the absorption cells used in optical pumping experiments have usually been quite difficult to obtain. In the present work, a pressure-scanned Fabry—Perot etalon has been used as a high-resolution device to obtain absorption profiles from which the alkali vapor densitys can be directly derived. The measurements have been made with sodium only, and the results of these experiments are graphs of the optical-pumping signal strength in a Dehmelt transmission arrangement as a function of the alkali vapor density. These graphs may be useful in estimating vapor densities in those optical-pumping experiments for which construction of the requisite spectroscopic equipment is not feasible.

Holograms were made with millisecond pulses from argon-ion lasers of 5-mm, 8-mm, and 15-mm bore diam operating in either the fundamental or higher order modes. The temporal coherence of the lasers was improved by an order of magnitude through use of an intracavity etalon.

A cw dye laser is described that provides tunable, high-power single-frequency radiation over the entire visible spectrum. Central to the design is the elimination of spatial hole burning and the enhancement of mode competition through the use of a ring resonator and a very-low-loss Faraday-effect device to select a single traveling-wave direction. As much as 0.9 W of single-frequency 580-nm radiation is available from rhodamine 6G using a 4-W 514.5-nm argon-ion laser pump. Intracavity second-harmonic generation has produced over 20 mW of tunable single-frequency ultraviolet radiation under the same conditions.