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Research on the characteristics, mechanism, and compensation method of the temperature-induced surface distortion of deformable mirrors
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Paper Abstract

We investigate the distortion caused by the differences between the working environment and the mounting temperature in the surface shape of the deformable mirror (DM) used in the National Ignition Facility. The characteristics of the surface distortion appeared on the DM under different temperature fields, such as the uniform and gradient working environment temperature, are studied in theory and experiments. Under the uniform working environment temperature, the distorted surface shape reveals the high-frequency and actuator-corresponding characteristics. The distorted surface shapes and their dependence on the actuators’ distribution and structural parameters of the DM are analyzed by using the finite element method. The analysis on the distorted surface shape under the gradient working environment temperature indicates that the changes of the peak and valley (PV) or root-mean-square (RMS) value rely on the temperature gradient as well as the difference between the mirror and the environment with a certain rule. To compensate the temperature induced surface shape distortion (TID), its essential mechanism is analyzed systematically based on the thermal stress characteristics, which shows that the actuators’ tilt caused by the thermal expansion coefficient difference between the mirror and the steel base is the essential reason. An efficient method based on an auxiliary temperature compensation module (TCM) and a hybrid closed-loop control algorithm (HCLA) are presented accordingly. In the simulation and the experiment, the DM’s TID could be effectively depressed and a well-compensated DM surface shape is finally achieved.

Paper Details

Date Published: 9 September 2019
PDF: 13 pages
Proc. SPIE 11107, Laser Beam Shaping XIX, 111070D (9 September 2019); doi: 10.1117/12.2525360
Show Author Affiliations
Chuang Sun Sr., Tsinghua Univ. (China)
Licheng Sun, Tsinghua Univ. (China)
Yamin Zheng, Tsinghua Univ. (China)
Shibing Lin, Tsinghua Univ. (China)
Huang Lei, Tsinghua Univ. (China)


Published in SPIE Proceedings Vol. 11107:
Laser Beam Shaping XIX
Angela Dudley; Alexander V. Laskin, Editor(s)

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