A Large-Aperture Remote Sensing Camera Calibration Method Based on Stellar and Inner Blackbody

Radiometric calibration of satellites is one of the core technologies for analyzing satellite data quantitatively. For large-aperture remote sensing cameras, the blackbody is placed in the rear optical path due to its weight and size. As a result, the front optics’ self-emission cannot be evaluated when the inner blackbody is observed. To achieve full optical path calibrations, stars are used as radiation calibration sources for large-aperture cameras. In high-energy concentration detection systems, the point spread function (PSF), intrapixel sensitivity (IPS), capacitive coupling, and sampling phase may cause some energy of the point source to be lost, resulting in an energy difference between the extended and point sources. It is important to note that conventional aperture photometry is not always the ideal method for obtaining high-precision photometry. This article proposes a method for compensation of point-source signals based on capacitive coupling correction, PSF reconstruction, and IPS model, and establishes a response conversion model for stellar and inner blackbodies. According to calibration coefficients based on stars and inner blackbody, the error between the star calibration coefficient and the inner blackbody calibration coefficient is 0.18%, which is better than 59.4% before the proposed method was applied. The error between the two methods can be stabilized within 0.3% within 140 days of the launch of the satellite.