Research on Far-ultraviolet Diffuse Standardization Device Technology for Spatial Calibration

With the rapid advancement of vacuum ultraviolet （VUV） space detection technology, the application of VUV optical payloads has become increasingly widespread. These instruments typically operate in orbit for several years or even decades, and regular calibration is performed during orbital operations to ensure the accuracy and reliability of measurement data. The calibration of VUV space payloads is divided into two main stages: laboratory calibration and on-orbit calibration. Laboratory calibration is conducted on the ground, and on-orbit calibration is performed when necessary after the payload is deployed into orbit.After prolonged orbital operation, the performance of optical components and detectors degrades due to various space environmental factors, such as solar radiation. Consequently, the original laboratory calibration coefficients become inapplicable, necessitating on-orbit calibration to provide updated coefficients. On-orbit calibration is crucial for the long-term operation and quantitative measurement of optical remote sensing payloads.In China, a common method for achieving on-orbit calibration involves combining the Sun and stars with a diffuse calibrator. The diffuse calibrator serves as a core component for the on-orbit calibration of VUV instruments. Solar spectral signals are relatively stable VUV sources. When reflected by a standard diffuse calibrator, these signals are converted into standard radiance for calibrating VUV space payloads. The reflection and radiation-resistant properties of the vacuum ultraviolet optical diffuse calibrator, as a core component, directly impact the accuracy of on-orbit calibration. Research on VUV optical diffuse calibrators in China started relatively late. This study aims to enhance the reflectance and radiation resistance of the diffuse calibrator through targeted design improvements, thereby ensuring the long-term effective operation of VUV space payloads. In this paper, a more efficient vacuum ultraviolet optical diffuse calibrator has been developed. It underwent space radiation tests to verify the relative attenuation rate and demonstrated relatively lower relative attenuation rates and ideal stability while ensuring coverage of the 120～200 nm wavelength band.