Abstract
(1) Background: The modeling, characterization, and mitigation of transient lasers, thermal stress, and thermo-optic effects (TOEs) occurring inside high energy lasers have become hot research topics in laser physics over the past few decades. The physical sources of TOEs are the un-avoidable residual absorption and scattering in the volume and on the surface of passive and active laser elements. Therefore, it is necessary to characterize and mitigate these effects in real laser systems under high-power operations. (2) Methods: The laboratory setup comprised a 10-kW continuous wave laser source with a changeable beam diameter, and dynamic registration of the transient temperature profiles was applied using an infrared camera. Modeling using COMSOL Multiphysics enabled matching of the surface and volume absorption coefficients to the experimental data of the temperature profiles. The beam quality was estimated from the known optical path differences (OPDs) occurring within the examined sample. (3) Results: The absorption loss coefficients of dielectric coatings were determined for the evaluation of several coating technologies. Additionally, OPDs for typical transmissive and reflective elements were determined. (4) Conclusions: The idea of dynamic self-compensation of transient TOEs using a tailored design of the considered transmissive and reflecting elements is proposed.
Highlights
High energy lasers (HELs) with an average power of 100 kW are required in the fields of science, technology, and the military [1,2,3,4,5,6,7,8]
We used a method based on the comparison of dynamically registered 2D temperature maps, via an infrared camera (IRC), with a model of a sample implemented in COMSOL Multiphysics
Transient 2D temperature distributions in laser optical elements under a 10-kW laser beam exposition were measured and compared to those obtained via numerical modeling in COMSOL
Summary
High energy lasers (HELs) with an average power of 100 kW are required in the fields of science, technology, and the military [1,2,3,4,5,6,7,8]. In the case of laser weapon (LaW) applications, such systems do not operate as steady-state, continuous-wave (CW) systems, as the required interaction time with a target is only a few seconds. The transient laser, thermal stress, and thermo-optic effects (TOEs) occurring inside a HEL and laser beam-forming tracking have to be characterized [9,10] and compensated. The characterization and mitigation of these effects are required in real laser systems operating under a high power [9]. Developing a technology for optical elements with such applications remains a great
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