The Research On Design Methods And Fabricating Technology Of Varied Line-Space Holographic Plane Grating

Varied line-space(VLS) plane grating has the ability of focusing, reducing aberration and flat field, which means that VLS plane gratings are well applied for monochromator of high resolution and grazing incidence in the soft X-ray and extreme ultraviolet(EUV) region. However, adjacent grating lattice spacing is at the nanoscale, the fabrication of VLS plane grating is extremely difficult. In this paper, the research is mostly focused on design methods and fabricating technologies of VLS holographic plane grating. Firstly, based on the relationship between the ability of focusing and grooving function, and the principle of aberration of VLS plane grating, the design method of grating groove function coefficient is proposed. The spectral resolution of VLS plane grating is also discussed. Secondly, single objective function is built based on the groove density function of the first generation spherical wave-front recording system, which is transformed from groove function. The improved local optimization algorithm which combines the advantages of local optimization algorithm and global optimization algorithm is proposed to be used in the optimization design of the recording parameters. The recording parameters of the VLS plane grating used in soft X-ray are calculated by three different optimization algorithm, the conventional local optimization algorithm, genetic optimization algorithm and the improved optimization algorithm. The analyses of the optimization results show that grating designed by the improved local optimization algorithm has better groove density and spectral resolution than the gratings design by the other two conventional optimization algorithm. The improved local optimization algorithm is more suitable in the spherical wave-front recording parameters design. Thirdly, considering fabrication of the VLS plane grating, studies the influence of the recording parameters error of spherical wave-front on grating groove density, focal curve and image width. Find out the main error affect the VLS plane grating imaging and propose the compensation method of the recording parameters error. Fourthly, the local optimization algorithm of the spherical wave-front recording parameters design and the compensation method of the recording parameters error are used in the design and fabrication of the VLS plane grating applied to an online grazing incidence spectrometer which covers the EUV region of 50 nm-150 nm. The groove density and spectral resolution of the designed VLS plane grating are analyzed. Based on the designed recording parameters, give the debugging method of the approximate grazing incidence recording system. The fabrication and test of the VLS plane grating are accomplished. The test results show that the groove density and spectral resolution of the fabricated VLS plane grating are similar with designed grating, which give guidelines for the design fabrication of the VLS holographic plane grating. Fifthly, analyzed the influence the groove curve of the VLS plane grating fabricated in the spherical wave-front recording system on the groove density and spectral resolution, the greater grating width, the lower spectral resolution. The VLS plane grating with greater width can’t be fabricated in the spherical wave-front recording system. Cylindrical wave-front recording system is put forward to fabricate straight groove VLS plane grating. Analyze and build the mathematical model of the groove density in the cylindrical wave-front recording system. Design the recording system used cylindrical mirror and slit as key component, provide theoretical guidance for the fabrication of straight groove VLS plane grating.