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The earth’s gravity field reflects the spatial distribution, movement and change of the earth’s mass. High precision gravity field is one of the main tasks of geodesy. The feasibility research of future China's satellite gravity mission(CSGM) were carried out, the satellite to satellite tracking in the low low mode was selected in the future satellite gravity measure. A precise laser ranging system is a key component to CSGM. In this paper, a laboratory breadboard heterodyne laser interferometer was built, experimental result demonstrated that laser ranging performance in laboratory distances was 1 nm@0.01Hz and below1nm@1Hz in translation measurement, and can meet the demand of CSGM mission.

Space gravitational wave detection, extraterrestrial life exploration and high-precision measurement of earth's gravity field have great scientific significance and wide application value. Inter satellite long baseline high-precision laser interferometry ranging technology can obtain high-precision inter satellite displacement variation, which is the key technology of the above space-based scientific engineering. The laser interference system transforms the inter satellite displacement into corresponding interference signals. The above-mentioned scientific plan has put forward extremely high precision, stability and wide bandwidth requirements for laser interference phase measurement. It can be seen that the high-precision laser phase measurement technology has become the bottleneck to further improve the ranging accuracy and stability. This paper researches the progress of high-precision laser phase measurement technology for space-based precision ranging at home and abroad, analyzes the demand of this technology in space-related fields and proposes the key technologies and preliminary schemes to be solved in the research.

Terahertz imaging is new trend of space optical remote sensing detection field. However, the resolution of Terahertz imaging is limited by the manufacture level of the Terahertz detector. In this paper we present the image processing method based Terahertz oversampling system. The multi-frames of observing same region are collected by our Terahertz imaging system. The shift displacement between adjacent frames is sub-pixel on the horizontal and vertical direction. The multi-frames are filtered by the norm constraint and enhancement. The higher resolution grid is reconstructed after the staggered frames are achieved. It shows that background noise is constrained and target edge is more continuous by the proposed method. The evaluation index of image quality is raised, which means that proposed method is better than other conventional method. The detail information of processed image is enhanced. The proposed oversampling method is special for dim target and background clutter data such as terahertz and infrared image, combining with the p2 norm optimization and bilateral filtering.

Aims Studies on the influences of forest succession on soil respiration (Rs) and its temperature sensitivity (Q10) are controversial, leading to uncertainties in the accuracy of global carbon budget. Our objectives were to deter- mine: (1) changes of Rs and Q10 in a succession series of mid-subtropical forests, (2) seasonal variations of Rs and its relationships with temperature and water content, and (3) the underlying mechanism of changes in Rs with suc- cession. Methods We selected stands of an evergreen broadleaved forest at the early successional stage (15 years), mid- dle successional stage (47 years), and late successional stage (110 years) under similar site conditions in Jian'ou, Fujian. Monthly Rs was measured by using an infrared gas exchange system from September 2009 through August 2010. Soil temperature and moisture were measured concurrently. The relationships of Rs with annual litterfall, fine root biomass, contents of soil organic carbon (SOC) and total nitrogen (TN) in the 0-20 cm soil layer were tested by linear regression analysis Important findings The average values of Rs were 2.38, 3.32 and 3.91 µmol·m -2 ·s -1 , and the average values of Q10 were 2.64, 1.97 and 1.79, respectively, in the early, middle, and late successional stages. Compared to in the early successional stage, Rs was increased significantly by 64.29% while Q10 was decreased by 32.30% in the late successional stage. The seasonal patterns of Rs were similar among the three successional stages; soil temperature and water content explained 69.5%, 81.9% and 61.3% of the seasonal variations. According to regression analysis, soil respiration was positively correlated with annual litterfall, fine root biomass, and contents of SOC and TN in the 0-20 cm soil layer. Succession promoted carbon emission and reduced soil respiration sensitivity in our study, which might be related to the increases in fine root biomass, carbon input and soil nutrient with forest succession.

In this paper, a modified Michelson interferometer is designed to measure Terahertz spectrum. Compared with normal Michelson interferometer, hollow retroreflectors are used instead of flat mirrors as reflective mirrors. The theory analysis and some measurement are given.

The main disadvantages of traditional spectral polarization imaging system are: complex structure, with moving parts, low throughput. A novel method of spectral polarization imaging system is discussed, which is based on static polarization intensity modulation combined with Savart polariscope interference imaging. The imaging system can obtain real-time information of spectral and four Stokes polarization messages. Compared with the conventional methods, the advantages of the imaging system are compactness, low mass and no moving parts, no electrical control, no slit and big throughput. The system structure and the basic theory are introduced. The experimental system is established in the laboratory. The experimental system consists of reimaging optics, polarization intensity module, interference imaging module, and CCD data collecting and processing module. The spectral range is visible and near-infrared (480-950 nm). The white board and the plane toy are imaged by using the experimental system. The ability of obtaining spectral polarization imaging information is verified. The calibration system of static polarization modulation is set up. The statistical error of polarization degree detection is less than 5%. The validity and feasibility of the basic principle is proved by the experimental result. The spectral polarization data captured by the system can be applied to object identification, object classification and remote sensing detection.