Optical window characterization experiment with laser-induced gradients

Stuart A. Jackson; Raymond M. Sova; Michael E. Thomas

doi:10.1117/12.2598137

12 September 2021 Optical window characterization experiment with laser-induced gradients

Stuart A. Jackson, Raymond M. Sova, Michael E. Thomas

Proceedings Volume 11866, Electro-Optical and Infrared Systems: Technology and Applications XVIII and Electro-Optical Remote Sensing XV; 118660K (2021) https://doi.org/10.1117/12.2598137
Event: SPIE Security + Defence, 2021, Online Only

Abstract

Optical window characterization is performed with a CO2 laser heating the material to understand the optical effects, thermal effects, and temperature dependence of the index of refraction. Distortions in the optical window caused by operating in challenging aerothermal environments can impact an imager’s performance. Uneven heating of the window will induce a temperature gradient, which when coupled with the temperature dependence of the refractive index, causes a flat sapphire window to act as an imperfect lens. Experimental capability allows multiple sensors and diagnostic equipment to collect synchronized data. A long-wave infrared (LWIR) camera images the sample’s front and back surfaces to measure temperatures and temperature gradients. A transmitted laser probe beam is captured simultaneously by a visible imager and wavefront sensor. The visible imager captures how a point source appears observed through the window. A transmitted wavefront is reconstructed from the wavefront sensor. The reconstructed wavefront includes effects from both dn/dT and mechanical deformation of the window. Using the reconstructed wavefront and imager optics in Zemax, the point spread function (PSF) of the imager looking through the heated window is generated and compared with the experimentally measured PSF.

Conference Presentation

Citation Download Citation

Stuart A. Jackson, Raymond M. Sova, and Michael E. Thomas "Optical window characterization experiment with laser-induced gradients", Proc. SPIE 11866, Electro-Optical and Infrared Systems: Technology and Applications XVIII and Electro-Optical Remote Sensing XV, 118660K (12 September 2021); https://doi.org/10.1117/12.2598137

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