Construction and Validation of a Geometry-based Mathematical Model for the Hard X-ray Imager

TL;DR

This paper develops and validates a geometry-based mathematical model for the modulation function of the Hard X-ray Imager, aiding in solar flare imaging and improving image reconstruction accuracy.

Contribution

It introduces a comprehensive mathematical model for HXI modulation functions, incorporating six degrees of freedom and validation through simulations and experiments.

Findings

Model accurately predicts modulation functions under various conditions.

Validation confirms the model's effectiveness with Geant4 simulations.

Application improves image reconstruction for solar flare analysis.

Abstract

Quantitative and analytical analysis of modulation process of the collimator is a great challenge, and is also of great value to the design and development of Fourier transform imaging telescopes. The Hard X-ray Imager (HXI), as one of the three payloads onboard the Advanced Space-based Solar Observatory(ASO-S) mission, adopts modulating Fourier-Transformation imaging technique and will be used to explore mechanism of energy release and transmission in solar flare activities. As an important step to reconstruct the images of solar flares, accurate modulation functions of HXI are needed. In this paper, a mathematical model is developed to analyze the modulation function under a simplified condition first. Then its behavior under six degrees of freedom is calculated after adding the rotation matrix and translation change to the model. In addition, unparalleled light and extended sources also are considered so that our model can be used to analyze the X-ray beam experiment. Next, applied to the practical HXI conditions, the model has been confirmed not only by Geant4 simulations but also by some verification experiments. Furthermore, how this model helps to improve the image reconstruction process after the launch of ASO-S is also presented.