| ICF high power laser driver system is a complicated large project. Technology of such project can be classified to two main categories: first is the research of energy conversion, which mainly focuses on the conversion and transfer of the 'energy stream', determines the efficiency and output of the laser system and mainly solves the problem to distribute the 'quantity' of the energy. Second is the research of laser beam, which mainly focuses on the 'parameter stream'- the technology to control the aberration of parameters in the transmission, determines the spatial output of the laser system and mainly solves the problem to improve the 'quality' of the laser beam.In this paper, the light beam condition of high power laser system has been discussed. Creative research has been carried in the technologies of temporal pulse shaping, spatial intensity shaping, angular spectrum dispersion, and wave front control, which cover four parameters of time, amplitude, spectrum and phase that describe the characteristics of a laser beam. We firstly bring forward and realize technologies of arbitrarily shaping laser pulse in the time domain by chirped pulse stacking, programmablely shaping spatial intensity by crystal liquid diaphragm, focused spot smoothing using angular spectrum dispersion by special gratings and detecting and compensating the small patch wave front aberration. Precise, programmable, efficient and 'all parameters' condition of high power laser system has been obtained. It provides a good way to improve the technology and performance of the next generation high power laser system. The research work has produced 10 papers and 1 patentThe content of this paper are:1. Temporal pulse shaping by optical pulse stacking:Precisely temporal shaping of optical pulse by chirped pulse stacking was brought forward. Feasibility, technique and relative technology of pulse stacking has been studied and stable precisely programmable shaped pulse was obtained. To suppress the noise of the stacked pulse, temporal pulse smoothing by spectrum filtering has also been studied. The stacked pulse has been injected to the front end of the laser driver, and experiments were carried.The research work has reached an international advanced level in the capability of precisely condition the temporal shape of optical pulse. It may be selected as the injection laser system of the ShengGuang III, which is the new generation high powerlaser system of our country.2. Near field beam condition:Programmable, feedback condition of near field beam by crystal liquid diaphragm was brought forward. The thesis of shaping spatial intensity of high power laser beam by crystal liquid diaphragm was studied. Experiments have been carried to study the amplitude, additive phase, and additive high spatial frequency modulation characteristics of the crystal liquid diaphragm. The transparence stability and transmission characteristic of the spatially shaped beam was also experimentally studied. Software for automatic feedback was developed. The crystal liquid diaphragm has been successfully applied to the 1CF high power laser system (the prototype of ShengGuang III) for the first time in the world.3. Spectrum control technology and its application researchBasic theory of smoothing by spectral dispersion in high-power laser system was studied. Periodical frequency modulation was obtained by chirped pulse stacking, and novel special gratings were proposed here to obtain angular spectral dispersion and temporal smoothing of focal spot. Spectrum modulation model of the stacked chirped pulse was established and its dispersion representation was deduced. Circular grating, star grating and grating array were proposed and designed. Smoothing characteristics of these special gratings were simulated. Results indicate some of the special gratings could obtain very good smoothing effects and have the potential for application. Besides, the problem of spectrum unbalance induced by phase modulation was studied and experimentally validated, which has been applied in the engineering practice.4. Investigation of wavefront control technologyCascade liquid-crystal diaphragm spatial light modulator and Fresnel zone plate array detecting technology were proposed to control the small-scale wavefront aberration. The principle, method and technology were given in the thesis.The propagation characteristics and influence of small-scale wavefront aberration on high-power laser system were studied. The feasibility using liquid-crystal spatial light modulator to control the small-scale wavefront aberration was analyzed. Radial shearing interferograms and Fresnel zone plate array wavefront cutting method was proposed to detect the small-scale wavefront aberration. Experiments have validated the feasibility of these methods, and the aim to effectively control the small-scale wavefront aberration is attained.The main innovation points are summarized as following:1. Based on all-optics method and the chirped pulse stacking technology, the principal, method and technology of high precision laser pulse shaping method was proposed and realized for the first time;2. The principal, method and technology of programmable and automatic feedback condition of near-field with liquid crystal spatial light modulator in high power laser system was proposed and realized for the first time;3. The principal of realizing temporal focal spot smoothing with one dimensional angular spectral dispersion of periodically chirped pulse by novel special gratings were proposed for the first time, The effects were very good, and some results were comparable with the three dimensional angular spectral dispersion;4. The principal, method and technology were proposed and realized for the first time to control small-scale wave-front distortion, using cascade liquid-crystal diaphragm spatial light modulator and Fresnel zone plate array wave-front detecting technology.
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