X-ray beam expansion system based on an asymmetric cut crystal

Ground testing and calibration of X-ray telescope imaging optical systems are usually necessary to ensure the performance of detection equipment and the success of scientific missions. This requires X-ray beams with large dimensions that can cover the full aperture of the telescope while maintaining high collimation. This paper focuses on the application requirements of large-sized X-ray beams for ground testing and calibration of X-ray telescope imaging optical systems and conducts a study on X-ray beam expansion system based on an asymmetric cut crystal. X-rays from a Ti-target X-ray source are first diffracted by a symmetric cut crystal Si(220) to produce highly monochromatic X-rays, and then diffracted by an asymmetric cut crystal Si(220) to achieve one-dimensional beam expansion. The mounting position of the asymmetric cut crystal Si(220) was determined based on the optical path and beam size of the primary diffraction light. The rocking curve of the asymmetric cut crystal Si(220) was further tested, with a full width at half-maximum (FWHM) of 0.043°, which can determine the optimal rotation angle of the crystal. The test results of the beam expansion performance of the asymmetric cut crystal show that the width of the secondary diffraction beam expansion light can reach ∼30mm, the effective expansion ratio is b=41, and the maximum total count rate of the diffraction peak is 129 cps. These results can provide preliminary verification and technical support for the establishment of a ground testing and calibration device with large-sized X-ray beams for X-ray telescope imaging optical systems.