Asteroid detection radar provides scientific data support for inversion of internal address structure and material composition by obtaining the reflection echo of strange medium on the surface and inside of the star. The detection method of asteroid companion determines that radar system can’t extract target echo form strong surface clutter without Doppler information in the detection process. At the same time, compared with Mars radar detection, resource constraints are more stringent, and the resolution are required higher. In this paper, a multi-point and multi-angle long time stepped frequency broadband synthetic detection scheme is creatively proposed, which effectively solves the contradiction between penetration depth and resolution, the SNR is not enough of sigle-pluse, and the extraction of target echo form strong clutter, etc., providing theoretical basis for the design of asteroid detection radar system.
The simultaneous imaging polarization camera (SIPC) is an instrument for simultaneous polarization measurement using a three-beam splitter prism. Due to the large number of polarizing devices in the SIPC, the parameters and responses of the polarizing devices are different, which causes the measurement matrix of the instrument to deviate from the ideal value. In order to ensure the polarization measurement accuracy of the SIPC, effective polarization calibration is required. In this paper, a standard linearly polarized light source is used to calibrate the SIPC. Firstly, the measurement matrix of the instrument is calibrated by using the linear polarization calibration source, and then the calibration parameters are obtained by fitting Fourier coefficients with least squares. Finally, the polarization measurement accuracy of the SIPC is verified by calibration experiments. The results show that the polarization measurement accuracy of the SIPC is better than 4% after polarization calibration.
To obtain high accuracy polarization observation information is highly expecting in aerosol parameter retrieval and atmosphere environment research. In this paper, we described a space-borne multispectral polarized scanning atmospheric corrector (PSAC), which can provide extremely high polarimetric accuracy. And we use wavelet-based denoising method to improve the stability of PSAC measurement results by reducing internal noise. The result shows that the STD of DOLP difference between PSAC measurement value and theoretical value is significantly reduced, reached 5%~10% in the requirement DOLP difference accuracy 0.5%, the proposed threshold function can increase the evaluation accuracy stability of instrument polarization and reduce the uncertainty, also, the measurement results of PSAC inflight improved as well.
In order to meet the application requirements of a space borne polarizing radiometer infrared band, a high-precision on-orbit temperature control scheme for the infrared detector combining active temperature control and passive temperature control is proposed. The infrared detector is installed on the heat sink copper block, and the temperature of heat sink copper block is controlled at -20°C~-30°C through the method of auxiliary cold plate + heat pipe thermal conduction. Combined with the infrared detector built-in three-level thermoelectric cooler, the photosensitive surface temperature of the infrared detector is cooled to below -60°C by a method of constant current driving. In order to ensure the measurement accuracy of infrared radiation polarization, the short-term temperature fluctuation of the photosensitive surface of the infrared detector is required to be less than 0.03°C/s. This article has designed the infrared detector temperature control scheme verification test, and actually measured the stability of infrared detector temperature and dark current. The results of the simulation and tests show that the range of infrared detector heat sink temperature is - 25±5°C, the range of infrared detector photosensitive surface temperature is -65°C ~ -75°C,the rate of short-term temperature change of the infrared detector photo-sensitive surface is better than 0.01°C/s, and the dark current fluctuation is less than 1.3pA. Satisfying the on-orbit high-precision polarization measurement requirements.
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