Dual-wavelength Satellite Laser Ranging

Satellite Laser Ranging(SLR)is a technique with the highest precision for asingle—shot measurement of satellites.It has achieved a ranging precision ofsub—centimeter.Due to the uncertainty of the existing atmospheric dispersion models,atmosphere correction has become one of the main obstacles to upgrade the laserranging accuracy.Two—wavelength laser ranging system that is independent ofatmospheric models can be used to determine the atmospheric delay by measuringthe differences in propagation time between two wavelengths.It may contribute torefinement of the existing models.The ranging precision of the 4'"generationsatellite laser ranging system is expected to be millimeter level.In order to reach aranging precision of millimeter,two·wavelength laser ranging technique can beemployed to calibrate the atmospheric delay correction with a higher precision.Upto now,such satellite ranging systems are still under developing. In this dissertation,Raman laser for multi—wavelength satellite laser ranging hasbeen developed.Combined with the existing SLR system at Shanghai AstronomicalObservatory,a novel design for laser transmitter has been used.An operationalsystem for two—wavelength SLR,including a dual—transmitting—channel and adual—receiving—channel,was established recently.We have carried out someexperimental ranging tests with a pair of 0.532um/0.683um to satellites Beacon.C.Ajisai,Topex,Starlette etc.Furthermore,preliminary analysis of the ranging data of two—wavelength satellite returns was performed.It shows no significant differencebetween the measured delay and the calculated one from Marini—Murray model. The two—wavelength satellite laser ranging system that developed in ShanghaiAstronomical Observatory is the first attempt in China.This system will play animportant role in domestic studying on two—wavelength satellite laser ranging.Some better technical details for this system iS still in consideration.and somesuggestions are proposed.