Satellite laser range system measures the distance between the satellite and the surface of the earth by figuring out the transit time of laser pulse. The beam is refracted when it goes through the atmosphere. The atmosphere refraction effect causes laser propagation delay and path bending, which is one of the key factors to restrict the accuracy of laser ranging. In order to improve the accuracy of atmospheric refraction delay correction, it is necessary to strengthen the study of atmospheric group refractivity models and atmospheric refraction delay correction method. According to the datum of Xuzhou upper air meteorological station, which are the monthly values of upper limit layers for 30 years (1981-2010) in China, three atmospheric group refractivity models were analyzed and compared. The atmospheric refraction delays to LiDAR were calculated by ray tracing method. The differences among the group refractivity models as a function of month and angle of direction were given, which lay the foundation for the practical application and precision evaluation of LiDAR.
The enhanced Raman spectroscopy (SERS) substrates were obtained using self-assembly Ag nanoparticles on the surface of glass modified with 3-aminopropyltrimethoxysilane (APTES), where the Ag nanoparticles were synthesized by aqueous reduction of AgNO3 with trisodium citrate. The surface morphology of thin films with assembled silver nanoparticles was studied with UV-Vis spectroscopy and SEM. With the probe molecule of Rhodamine 6G, the Raman spectra on self-assembled Ag nanoparticle substrates were detected, which showed a great increase of Raman signals for Rh6. The surface plasmon resonance (SPR) of the assembled silver nanoparticles depended on the distance between the particles, the adsorption of molecules, and the assembly structure. Experimental results indicated that he intensities of the Raman peaks increased concomitantly with the increase in the concentration of Rh 6G. The detection limit of the assembled Ag nanostructures was 10<sup>−8</sup>M. In this paper, the results further confirmed that the nanoparticles assembled method was an effective method for the increase the signal of SERS.