Application Of Artificial Neural Network To The Thermal-optical Performance Research Of The Space Optical Window

Optical window with strict optical index is one of important parts of optical imaging system of space camera. Because window is exposed directly to space thermal environment, it is affected strongly by alternant temperature loads, which cause large temperature gradient on the window, then produce aberrance and refractive index change of window glass, finally affect optical performances of window. Fields of window temperature must be effectively controlled in order to meet window optical requirements in space environment. Namely windows temperature level and distribution asymmetry are ensured by thermal control system within allowable range. Difficulties of thermal control are rigorous thermal control index based on strict optical criterion of optical window7. So research on experiments of the window thermal-optical performance, thermal compensation mechanism and thermal control strategy has been carried out.In this paper, firstly Thermal-optical analysis method and experiment way arentroduced. It is pointed out that establishing thermal -optical performance model is very essential and the artificial neural network can be applied to set up thermal-optical model. After analyzing the thermal environment of windows, related active and passive thermal control way and its work principle are introduced.It is acquired by experiment that is relating to camera optical resolution and temperature field of window glass. Camera optical resolution corresponding to different temperature distribution obtained by the window active thermal control system, is got by taking pictures.A artificial neural network model concerning window glass temperature distribution and camera resolution is constituted, building a three-layer BP network model in which windows glass three point temperature value is considered as network input, camera resolution as network output. Trained BP neural network can better simulate window thermal梠ptical performance.For farther knowing the relation between windows outer surface film heater electric field and temperature distribution relation, the working capability of film heater is obtained through experiment.It may be improved to keep temperature level of window to great extent by using passive thermal control way, but asymmetry of window temperature fieldIt may be improved to keep temperature level of window to great extent by using passive thermal control way. but asymmetry of window temperature field must be compensated by window frame heater and film heater. Based on thermal analysis of window component, relevant strategy of thermal control is put forward.