Theoretical Study Of Laser-plasma X-ray Imaging By Using A Novel Zone Plate

The thesis is devoted to soft x-ray single order focus zone plate and soft x-ray single order diffraction grating, and the specific work consist of two fields: 1. the design and simulation work of one new binary Gabor zone plate; 2. the simulation and experiment work of the diffraction patterns of the new soft x-ray spectroscopy photon sieves.The soft x-ray microfocus Fresnel zone plate and soft x-ray transmission grating spectrometer play important roles in the ICF research and diagnose on the laser-plasmas interaction. The former is a potential alternative applied in back imaging of targets in the ICF research and micro-spot, ultra-short-pulse K ray imaging from ultra-short, ultra-intense laser and target interaction, and the latter hasbeen widely used in the fields of spectrum diagnose in ICF and high-field physics research.The Fresnel zone plate behaves as a multi-order lens, which generates spectra in multiple orders. Most imaging applications use the first diffraction order; however, the high-order images may overlap on the first order image and make the imaging quality decline. The traditional soft x-ray diffraction grating generates spectra in multiple orders as the Fresnel zone plate. Most soft x-ray spectroscopies applications use only the first diffraction order, but the higher-order diffraction may overlap on the first order diffraction and introduce errors in unfold process.Based on the review of the scalar diffraction theory, a new design of the x-ray single focus zone plate is proposed which is made up of a number of annulus-sector-shaped elements quasi-random distributed on the zones. Every zone consists of a number of annulus-sector-shaped elements which obey sinusoidal distribution along the radial direction and random distribution along the azimuthaldirection. Many such zones form a binary Gabor zone plate. Its diffraction pattern is simulated using MATLAB and shows that the high orders are absolutely restrained and only 1st order appears on the optical axis which suggests it can get rid of the higher orders to improve the imaging quality. At last, the feasibility of its fabrication is discussed.And then, the principle of the new modified spectroscopy photon sieve designed by the Leifeng Cao team in the China Academy of Engineering Physics is represented in detail, a numerical program is developed to research the diffraction patterns of different pinhole arrays and different apertures, and the advantage of its diffraction pattern and the feasibility of its fabrication are discussed. The theoretical research and simulation results show that the quasi-random circular-aperture-array spectroscopy photon sieve and the sinusoidal-distributed square-aperture-array spectroscopy photon sieve can get rid of the inevitable higher-order diffraction in the traditional x-raydiffraction grating spectrometer.The visible light spectroscopy photon sieve is designed and fabricated. Its diffraction pattern is measured. The experimental results showed that: the spectroscopy photon sieve can restrain third order and higher orders, second order disappeared, and only 0^th, 1^st orders existed. It s proved that our design is proper and its diffraction pattern is much more excellent than that of the conventional black-white transmission grating.