Wavefront and Pointing Transmission Modeling and Optomechanical Coupling Analysis for the Target-Area Section of Picosecond Petawatt Laser Facility

To meet the analysis requirements of large-aperture back-supported optical elements in the target area of picosecond petawatt laser facilities under multi-attitude installation, multi-element cascaded transmission, and stringent wavefront constraints, this paper establishes an optomechanical transmission analysis model. To address the high computational cost of existing full-scale finite element methods and the difficulty of ideal system-level optical models in accurately reflecting the effects of back-supported structures and alignment boundary conditions, a rapid prediction model for additional surface figure is developed at the element level, and a wavefront and pointing analysis model considering the cumulative effects of non-ideal surface figures is established at the transmission level. In this way, a continuous analysis from alignment input and installation attitude to system transmission performance is achieved. The model is validated through subcomponent experiments and multi-element transmission simulations. The results show that the proposed model can effectively capture the dominant characteristics of the additional surface figure and its evolution, and can also accurately describe the cumulative propagation of wavefront distortion along the transmission chain. Specifically, in the subcomponent experiments, the maximum PV deviation is controlled within 47 nm, and the maximum GRMS deviation does not exceed 0.92 nm/cm. In the transmission analysis, the absolute wavefront PV error is controlled within 30 nm. Overall, the proposed method maintains good prediction accuracy while retaining computational efficiency, and can provide effective support for the rapid engineering evaluation of large-aperture back-supported optical elements and the performance analysis of multi-element transmission chains.