High-power Laser Drive Target Surface Light Intensity Spatial And Temporal Coupling Control Technology

Beam quality control in high power solid state laser facility construction,especially beam intensity of target plane control,has been extremely required in precise physics experiments. To meet the requirements,the focal spot should be controlled.This dissertation focused on the focal spot needed in the inertial confinement fusion(ICF),based on spatial spectrum analysis, have studied some different ways to control focal spot,such as continuous phase plates(CPP), smoothed by spectral dispersion(SSD) and so on.The main research topics included:1.The ways of designing CPP used for focal spot shaping was researched and afterwards an improved G-S algorithm was put forward.It included some new features: introducing the spectrum function of focal spot that was related with temporal beam smoothing,applying the filtered random phase as initial phase and utilizing the unwrapping and filtering steps to meet CPP surface agreeing with the technique of production.With the designed CPP,the property and rules of focal spot was researched theoretically.The result was analyzed by numerical simulation to ensure the validity of the improved method.2.The error impacting CPP capability was analyzed,and so the error models of CPP that from manufacture to application was built.With the models some rules of impact factors was got in quantity.Then the frequency-tripled efficiency and beam quality affected by 1ωCPP was explored and so the applying condition was confirmed.With the CPP rules and measured results,the experiment program was proposed.3.The temporal beam smoothing technique was researched based on focal spot spatial spectrum analysis.Then the way of SSD by generalized phase modulation was researched theoretically more deeply and spatial frequency response function relating with smoothing essential property was thereby put forward.The influence laws of spatial frequency response function by SSD parameters were researched detailedly.Finally the application of multidimensional SSD and polarization smoothing(PS) together was researched to give the optimized coupled effect.4.The source of spatial frequency modulation by CPP was researched theoretically,and so CPP and temporal beam smoothing coupled effect problem was derived.The evaluation rule in different physics experiments was put forward for the first time by tracing to the sources. With the rule,the method of coupling CPP and temporal beam smoothing was put forward. Basing on the beam aberration model that meets experimental data,the tolerance capability of focal spot controlled by CPP and temporal beam smoothing was explored.