Calculations of the Frequency Dependence of Elasto-optic Constants of Infrared Laser Window Materials


Book Description

Stress-induced birefringence may severely degrade or limit the optical performance of infrared transmitting materials, especially in high power laser applications, Thus, prediction of this phenomenon is essential for the appropriate selection of high power IR laser window materials for numerous applications. In this report a detailed first-principles calculation of the elasto-optic, or strain-optic, constants p sub ij is carried out for the first time throughout infrared frequencies, employing a recent theory of Humphreys and Maradudin. For ionic crystals, a Born-Mayer interatomic potential is used, while for semiconductors a Morse potential is used. Two methods for obtaining the p sub ij are applied: one incorporates parameters based on standard thermodynamic prescriptions, the other combines these same parameters with additional ones derived from pressure-dependent data. For both cases, the dispersions in the p sub ij, as well as in the thermal lensing parameters, are calculated throughout the IR regime for a wide variety of rocksalt- and zinc blende-structure compounds.




Laser Window and Mirror Materials


Book Description

Charles S. Sahagian Chief, Electromagnetic Materials Technology Branch Deputy for Electronic Technology Hanscom AFB, MA 01731 I t should not be surprising that an event as significant as the discovery of the laser has had some con comitant impact on other areas of science and technology, but the extent of the impact was grossly unpredicted. Upon perusal of this bibliography, devoted to the subject of laser window and mirror materials, it becomes very apparent that the effect of the laser on materials R&D has been enormous. Several hundred papers and reports, representing millions of dollars of effort, have been promulgated over the past decade; and as new frequencies, improved tunability, higher power, and other charac teristics are achieved, we can expect even greater demands and requirements on the materials com munity. What are some of the highlights disclosec by this bibliography with regard to work already ac complished? First, one can note the extensive investigations into developing new materials while at the same time improving old ones. Among the latter, alkali halides, for example, have essentially had a rebirth. I n the past five years more progress has been achieved in the chemical and structural perfec tion of this class of materials than in the entire preceding century. Also carried along in the surge for improved laser materials have been the alkaline earth fluorides (prime candidates for 3-to 5-J,Lm ap plications), chalcogenides, semiconductors, oxides, and others.










Photoelastic and Electro-Optic Properties of Crystals


Book Description

This comprehensive treatise reviews, for the first time, all the essential work over the past 160 years on the photoelastic and the closely related linear and quadratic electro-optic effects in isotropic and crystalline mate rials. Emphasis is placed on the phenomenal growth of the subject during the past decade and a half with the advent of the laser, with the use of high-frequency acousto-optic and electro-optic techniques, and with the discovery of new piezoelectric materials, all of which have offered a feedback to the wide interest in these two areas of solid-state physics. The first of these subjects, the photoelastic effect, was discovered by Sir David Brewster in 1815. He first found the effect in gels and subsequently found it in glasses and crystals. While the effect remained of academic interest for nearly a hundred years, it became of practical value when Coker and Filon applied it to measuring stresses in machine parts. With one photograph and subsequent analysis, the stress in any planar model can be determined. By taking sections of a three-dimensional model, complete three-dimensional stresses can be found. Hence this effect is widely applied in industry.













R & D Abstracts


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Report on Research at AFCRL.


Book Description