Research on the design and characteristics of multi-grating modulation screen for tabletop Xray system

The desktop X-ray system has the limitations of low flux and poor coherence. It faces great challenges in application scenarios such as microscopic imaging and high-precision measurement. Fourier-transform ghost imaging (FGI) has low requirements on the coherence of the light source. Based on this principle, multi-angle FGI based on spatial correlation can effectively improve the imaging efficiency and is suitable for desktop X-ray systems. However, this technology is still in the theoretical stage, and there is a lack of effective devices to modulate Xrays and form focused multiple beams. To this end, a multi-grating modulation method is proposed in this paper. The partially coherent radiation of the X-ray source is modulated by arranging multiple subgratings in a specific direction. The X-ray emitted by a single sub-grating is spatially coherent light, and the X-rays between the sub-gratings are incoherently superimposed at the sample position to form a focused multiangle beam. This effectively improves the flux utilization of the desktop system. The modulation principle of multi-grating is described theoretically, and the key design parameters and their selection basis are clarified. Through numerical simulation, the modulation characteristics of partially coherent X-rays in the propagation process behind the modulation screen are systematically analyzed. By optimizing the parameters such as the size, material and thickness of the sub-grating, the influence of the sub-grating on the size, uniformity and diffraction efficiency of the focused spot is studied. The results show that when the sub-grating size matches the spatial coherence size of the X-ray source, the focusing effect of the beam can be significantly improved, and a smaller and uniform focal spot can be obtained. Based on the theoretical and simulation results, a gold multi-grating modulation screen is designed and fabricated for the liquid target X-ray source. Experimental validation of the simulation and theoretical predictions will be conducted once the experimental conditions are met. Once the experimental conditions are fulfilled, the focusing performance of the modulation screen will be further verified. The design and implementation of the modulation screen provide effective support and feasible path for multi-angle diffraction imaging and related applications in miniaturized X-ray systems.