Study Of Long Focal Depth Optical Elements Applied In The Diagnosis For Inertial Confinement Fusion Plasmas

In the shooting experiment of inertial confinement fusion (1CF), in order to monitor coupling efficiency between the laser and target, Thomson scattering is generally used to diagnose the parameters of the laser-produced plasmas, such as the electron density, electron and ion temperatures. For the sake of improving the spatial resolution so as to measure the parameters of plasmas in the different area, the probe laser beam is supposed to has long focal depth, small focal spot and side lobe. However, neither of the usual focusing elements, such as lens, refract ion-diffraction hybrid element, diffractive optical element, can satisfy all these requirements. A new technique that can meet all these requirements is desiderated for the plasma measurements.Motivated by the establishment of prototype of laser facility and targeted for developing focusing technique for satisfying the instant requirements of 1CF. a logarithmic axicon integrated with optical information processing technique such as edge smoothing, apodization, is first used to the diagnosis system in 1CF divers. So the axicon has been optimized , and the application of axicon is also expanded. It shows that the optimized axicon can meet the requirements of the diagnosis through theoretical analysis and numerical simulation.In this dissertation we demonstrate that a simple lens or a composite lens, which are both spherical surfaces and designed by nonlinear fitting of phase, can be used in place of the axicon. The long-focal-depth lens utilizes two or more spherical surfaces only to duplicate the performance of a logarithmic axicon and to create an extended focal line. The advantage is that spherical surfaces are routinely produced in any optical workshop, so the lens axicon is easy and inexpensive to manufacture. The nonlinear fitting of phase use in this dissertation can give a new method for the design of optical elements.Finally, according to the practical application of the logarithmic axicon and long focal lens in the 1CF system, the influence caused by low frequency and median high frequency disordered...