Aimed at key problems the system of 1:5000 scale space stereo mapping and the shortage of the surveying capability of urban area, in regard of the performance index and the surveying systems of the existing domestic optical mapping satellites are unable to meet the demand of the large scale stereo mapping, it is urgent to develop the very high accuracy space photogrammetric satellite system which has a 1:5000 scale (or larger).The new surveying systems of double baseline stereo photogrammetric mode with combined of linear array sensor and area array sensor was proposed, which aims at solving the problems of barriers, distortions and radiation differences in complex ground object mapping for the existing space stereo mapping technology. Based on collinearity equation, double baseline stereo photogrammetric method and the model of combined adjustment were presented, systematic error compensation for this model was analyzed, position precision of double baseline stereo photogrammetry based on both simulated images and images acquired under lab conditions was studied. The laboratory tests showed that camera geometric calibration accuracy is better than 1μm, the height positioning accuracy is better than 1.5GSD with GCPs. The results showed that the mode of combined of one linear array sensor and one plane array sensor had higher positioning precision. Explore the new system of 1:5000 scale very high accuracy space stereo mapping can provide available new technologies and strategies for achieving demotic very high accuracy space stereo mapping.
The image space scanning system is widely used for multichannel infrared imaging to overcome the absence of large infrared focal plane array. The field of view of afocal system directly influences the time resolution of the image space scanning system. The field of view of afocal system is generally less than 7°. Therefore, it is significant to design larger field of view of afocal system for increasing time resolution. The method of four-mirror afocal system design based on primary aberration is explored. The structural parameters are calculated according to magnification and obscuration ratio of each mirror. The conic parameters are calculated according to primary aberration coefficients. The procedure for calculating initial structural parameters is programmed. Then a four-mirror afocal system is designed with an entrance pupil diameter of 200mm, a field of view of 20°×1°, the operating wave band of 3~12μm, compression ratio of 2.5 times and the distance of exit pupil of 620mm. The results indicate that the maximum root mean square (RMS) wavefront error is less than 0.042λ(λ=7.5μm), the maximum optical path difference(OPD) is less than λ/4(λ=3~12μm). It has high imaging quality and the modulation transfer function (MTF) is approached to the diffraction limit. The method of afocal system design can be widely used for wide field multichannel infrared imaging.
Along with the further application of optical remote sensing, it becomes main trend to realize high spatial resolution, high time resolution, high spectrum resolution and high irradiance sensitivity simultaneously. We present a new satellite-based imaging system that will provide images with these high performances. The structure of the system is compact with small size and light weight. The IR imager, a new generation of high resolution optical remote sensing, is universally acknowledged as the most effective approach to surveil dynamic changes in the environment on the earth. Pushbroom imaging fashion with high efficiency and long-array focal plane detector with passive cooling are adopted to realize area imaging relevant to the flight direction of satellite. The instrument is a dual-optical-path system with long-wave infrared (LWIR) and mid-short-wave infrared (MW-SWIR) bands，which has 4 narrow spectrum bands respectively. An IR dichroic beam-splitter is use to divide wideband incident infrared into LWIR and MW-SWIR. Then two pieces of joint filters, which are integrated in front of detectors and then enveloped by IR Dewars, are used to divide the LWIR and MWIR into 4 spectral bands separately. The focal plane arrays (FPA) are fixed on the optical imaging plane of the lens. The LWIR and MW-SWIR FPA are cooled around 80K or even below. For cooled FPA, optical system must provide a real, accessible exit pupil coupled with a fast f/number refractive component in a Dewar and very close to the FPA. Compared to traditional infrared instruments, high spatial resolution and spectrum resolution can be obtained simultaneously within mass, volume and performance constraints.