The effective area calibration precision analysis of grazing incidence soft x-ray optical system

The grazing incidence soft X-ray optical system is the core equipment of future space science missions. The optical system expands the collecting area of x-ray photos and improves the SNR. The effective area calibration is the key indicator for testing and verifying the performance of the grazing incidence optical system. One of the traditional calibration methods uses the wide x-ray beam as the calibration x-ray source. This calibration method requires large ground equipment, high environmental conditions while the x-ray beam is not so parallel that the calibration accuracy is limited. Another effective area calibration method uses the narrow x-ray beam scan the optical system. In this paper, the above two effective area calibration methods of the grazing incidence optical system are modeled mathematically. The factors such as the parallelism of the beam, the uniformity of the beam and the characteristics of optical system are absorbed into the unified mathematical model for describing the effective area. The key factors which affect the effective area calibration accuracy are extracted, and their influences on the calibration result are analyzed. Eventually the two calibration methods accuracy is evaluated and the ways for improving the calibration accuracy are given. The effective area calibration is able to test and verify the collecting ability of x-ray photons of the grazing incidence optical system, which is the basis for the development of soft x-ray optics.