Precision Phase Active Control Technology

There are a lot of factors leading to wavefront distortion, and influencing beam quality. In order to achieve high coupling efficiency between laser beam and target, the phase must be precisely controlled to achieve the special focal irradiance profile. This article is based on the idea of full frequency wavefront control, and proposes the concept of active precise phase control. The main contents are as follows:Firstly, basing on the phase spectrum method, we studied the influence of precise phase to the far-filed energy concentration. Then, we give the spectrum evaluation method of deformable mirror. The control results of DMs with different actuators are compared, and there are some advantages of high order DM:frequency expansion of control, and increasing of peak power. The coupling relation between DM and pin-hole is also studied.Secondly, the optimum study of piezoelectric film deformable mirror (PFDM) is done. We build a mathematical model of this DM, and the coupling coefficient and beam aperture are discussed based this model. Then, the finite element model is build, and the main material parameters are studied and optimized. The griping method is also studied based finite element model, and some improving methods are proposed and demonstrated.Thirdly, the method of focal irradiance profile control with high order DM is proposed. The influencing of coupling coefficient and wavefront distortion is discussed. Then a method to achieve high spatial frequency with dual-deformable mirror is proposed. The main questions of its application are discussed.Finally, some other technical approaches are studied. Firstly, from the ICF laser beam smoothing of physical requirements, analyzes the focal spot uniformity of defocus shooting; secondly, analyzes and compares a wide range of focal spot active control algorithms. The SPGD algorithm, SA algorithm are studied in detail. The main control parameters are optimized and a common improving method is proposed.