Jia-Wei Li

We developed a new source, having uniform spectral radiance, for a large-aperture UV integrating sphere with pressed polytetrafluoroethylene coating. Since lamp panel systems have high uncertainty due to a low signal-to-noise ratio at 250 nm, to transfer the spectral radiance scale from 250 nm to 350 nm to the source, we developed and calibrated a filter radiometer based on a solar blind phototube. The spectral radiance was obtained via a model of the source and a recursive estimation of the model parameters. A standard FEL lamp validated the usage of the filter radiometer. Finally, the filter radiometer to calibrate the new source. The results show that the radiance of the source at 250 nm is five times the top-of-the-atmosphere spectral irradiance, and the expanded uncertainty is 4.7%.

To realize high-precision and high-frequency unattended site calibration and detection of satellites, automatic direction adjustment must be implemented in mirror arrays. This paper proposes a high-precision automatic calibration model based on a novel point light source tracking system for mirror arrays. A camera automatically observes the solar vector, and an observation equation coupling the image space and local coordinate systems is established. High-precision calibration of the system is realized through geometric error calculation of multipoint observation data. Moreover, model error analysis and solar tracking verification experiments are conducted. The standard deviations of the pitch angle and azimuth angle errors are 0.0176° and 0.0305°, respectively. The root mean square errors of the image centroid contrast are 2.0995 and 0.8689 pixels along the x- and y-axes, respectively. The corresponding pixel angular resolution errors are 0.0377° and 0.0144°, and the comprehensive angle resolution error is 0.0403°. The calculated model values are consistent with the measured data, validating the model. The proposed point light source tracking system can satisfy the requirements of high-resolution, high-precision, high-frequency on-orbit satellite radiometric calibration and modulation transfer function detection.