Beam Control And Diagnostic Assistant Technical Research On High-Power Laser System

The drive facility is the key technical step for controlling the inertial confinement fusion(ICF).The high power laser facility is selected as the ideal ICF drive device for the reason that the laser can produce the high power intensity and spatial interference which meet the temporal pulse length and shape requirements for physical experiments.The assistant optical issue and key technique of beam control and parameter diagnostic in high power laser system are discussed in this paper.1.The shear interferometer method is used in evaluating installing status of the beam image-relaying test system.In the distribution measurement image-relaying system of high power laser,the phase modulate is produced by the laser converge point diverged from the lens focus in axis between two lens in 4-f system as the test system installed.First the interference pattern in the image plane of the 4-fsystem was measured using sheared interference laterally experiment.And the academic relationship between the off-focus values and interferential fringe interval using lateral sheared interference test method was deduced by the matrix optic theory and Collins diffraction equation. The laser transmission relationship in space and frequency are also derived in the condition of where having no off-focus values.The interference pattern gray-level curve was fitted using minimum mean-square error method,and the off-focus values was calculated by the interferential fringe interval which is received using curve fitting.The installing states of the test system are quantity expressed using the off-focus values.This interference algorithm can be used for quantitative describing the in-line working status of beam near-field measurement image-relaying system.2.The algorithm for aligning cavity mirror which applied in off-axis four-pass amplifier high power laser facility is detailed analyzed in this paper.The beam automatic alignment is the key technique of high power laser system. Aiming at the scheme of using image-relaying of pinholes in multi-pass amplifier, the laser field distribution was deduced using Collins diffraction theory based on matrix optic method.The measurement optical system was designed for test the alignment of the cavity mirror,and this test system is also applied in the simulation physical experiment.The physical character describing of measurement optical system designing for aligning cavity mirror and algorithm study of far-field image processing in aligning cavity mirror based on edge curve characters are developed in this paper.Based on the ICF prototype facility requirement for aligning the cavity mirror,aiming at the laser image in aligning cavity mirror of high power laser system,the edge characters of light are quantitative analyzed by image processing. Combining the light transfer qualitatively analysis of measurement optical system for aligning cavity mirror,the consistency of different curve edge and the circular degree of the laser image are used for quantitative estimated the azimuth of cavity mirror.3.The light modulating in laser near-field beam imagery was studied in this paper,which is caused by the optical component flaw mainly in the near/far laser field distribution measurement system.Near field diagnostic is an important parameter for ICF laser performance.The reason which causes dark spots fringes in laser near field distribution are qualitative analyzed from physical optics viewpoint.The light modulation is the associated effect between laser distribution,optical aperture and laser diffractive phenomenon. A series academic calculation was done in this paper to simulate this physical phenomenon.As the influence of the flaw in optical component,the laser induced damage is potential exist the place where the laser energy density is very high. Aiming at the engineering requirements,an assistant measurement optical lens was designed for online inspecting optical flaw using in laser parameter sensor packages in this paper.According to the requirement of limited working space,the structure of lenses is a stop iris postposition which field nearly views telecentric,and optical image is obtained directly with CCD cameras.Finally,the working emphasis in this paper is summarized,and some advice is also put forward to the potential assistant technical research areas in the beam control and parameter measurement system.