High Ultraviolet, Through The Preparation And Performance Of High-energy Laser Window Materials

The development of high energy lasers(HELs),especially the airborne laser (ABL) system set a higher standard for materials of optical windows.It requires optical windows capable of handling mega joule beam energies without inducing significant wave front distortions when it goes through the window which will degrade the system's ability to hold a diffraction-limited focus on target.Such distortions mainly result from deposition of laser energy on the surface and in the bulk of the optical windows and the following thermal lensing problem(the progress of beam defocusing and beam distortion caused by thermally induced phase aberrations) due to the windows' absorption of laser energy.This energy deposition will not only affect the optical quality of the beam but also the mechanical performance of the optical window.In order to resolve such a problem,many methods are used,one of the most important ways is to select a proper material with negative thermo-optic coefficient that can efficiently avoid the threaten of thermal lensing.Such a material may help to fabricate"athermal windows"that can meet people's requirement.Among this kind of materials,□xyfluoride glass(OFG) and fusion-cast CaF2 have stimulated great expectation for creating such an athermal window.A method of evaluating performance of materials for large-scale laser window is established and is used to compare the performance of two materials that have good prospect as candidates for athermal laser window—Oxyfluoride Glass(OFG) and fused CaF₂.The compare between OFG and CaF₂ include two main aspects:their optical performance and their mechanical strength.According to the result of the compare,OFG perform better in resistance of optical distortion,and the mechanical properties of both OFG and CaF₂ should be well strengthened.Because of its great stability,machinability and adjustability in composition,OFG is recommended as having better prospect of creating an athermal laser window.Haven decides to take OFG as the proper material for athermal laser window,in order to get proper OFG,first of all we throughout investigate all the factors that may affect the property of OFG On this basis,we designed a new fluorophosphates glass system P₂O₅-(AlF₃+ZrF₄)-(CaF₂+SrF₂+BaF₂)-YF₃,and stable glass samples are produced successfully.