Similarity of laser window thermal effects

Abstract

We are concerned with the similarity and scaling law of the thermal effects of windows subjected to laser propagation and influences on laser beam quality. Using characteristic physical quantities and dimensionless equations, appropriate similarity relations are derived, independent of the specific properties of the materials and beams. As an example, a full-scale and a half-scale window are numerically analyzed to verify the relations. It is concluded that the phase aberration resulting from thermal deformation and thermo-optic effects comply completely with similarity-based scaling, while the phase aberration resulting from elasto-optic effects scales approximately. From the results of a model window, the performances of a full-scale window can be obtained using the similarity relations.