Development of laser mirrors of very high reflectivity using the cavity-attenuated phase-shift method.

It has been possible to obtain mirrors of very high reflectivity by following the simple four-step procedure described herein. The key to success is the ability to measure the scattering and other losses of the substrates and dielectric coatings to ensure that the specifications are being met. These measurements are especially critical in the important cleaning process. The cavity-attenuated phase-shift (CAPS) method is ideally suited for performing these important measurements, permitting us to obtain mirrors with reflectivities of R = 0.99975 +/- 0.00005.

Sensitive measurement of photon lifetime and true reflectances in an optical cavity by a phase-shift method.

A simplified method for measuring the effective photon lifetime in an optical resonator was developed. The technique requires the passage of a modulated cw laser beam through the resonator and the measurement of the resultant shift in the phase of the transmitted intensity. The method not only permits a quick and precise measurement of the mirror reflectances, but also permits these measurements to be in situ. Such an on-the-spot evaluation capability should be extremely useful in applications ranging from the investigation of new laser systems to the development of improved optical coatings. The method is also sensitive to the effects of absorption, scattering, and transmission from elements in the cavity. Cavity losses <100 ppm were detected.

Continuous-wave (F + H(2)) chemical lasers: a temperature-dependent analytical diffusion model.

The development of an analytical model for predicting the performance of HF lasers that result from the mixing of atomic fluorine with molecular hydrogen in continuously flowing systems is described. The model combines a temperature-dependent solution for a premixed laser system with laminar or turbulent flame-sheet mixing schemes to generate closed-form expressions for the two conditions of constant pressure (simulating a free jet) and constant density (simulating a partially confined flow). The various approximations, including a fully communicating cavity and characteristic reaction and deactivation lifetimes, are discussed. Scaling laws that relate power to the total pressure and nozzle parameters are developed. Comparison with exact numerical treatments for a wide range of conditions reveals that the model is consistently accurate to ~10%. Finally, the sensitivity of the predictions to the kinetic rate package and the utility of the model for performing parameter studies are indicated.