Long-range Non-cooperative Target Laser Altimeter Performance Verification

Laser ranging was one of the first applications of laser technology. Due to the uncertainty of factors such as far- range, atmospheric attenuation and operated target, a steady and reliable method and setting to characterize laser altimeter's performance is an important and difficult technology.The maximum range is the most important specification for a laser altimeter and 200km is the required level for the spaceborne laser altimeter in the lunar resources survey. In the paper, one kind of method and setting characterizing the laser altimeter's performance aiming at the specification of maximum range -noncooperative regulable attenuation was put forward and founded.Range-finding equations are the theoretical base for laser ranging. On the basis of the range-finding equations for target with different property, including cooperative and noncooperative object, and the properties of lunar surface, the equation for moon-ranging from satellite was deduced. Based on the analysis of the effect on the maximum range of the equation's each parameter and the traditional method of extinction ratio, the noncooperative regulable attenuation-measure the minimum detectable power of laser altimeter on the condition of constant miss probability by attenuating the laser power transmitting to the diffuse reflected simulant target-was put forward. According to the parameters such as minimum detectable power, range and reflectivity of simulant target, meteorological visibility and optical efficiency, the maximum range of laser altimeter was figured out by the range-finding equation.According to the minimum detectable power required by the spaceborne laser altimeter for 200km maximum range and the analysis result of the effect between the maximum range and the equation's each parameter, the specifications for noncooperative regulable attenuation setting were fixed on. Based on the model of resource survey spaceborne laser altimeter, the noncooperative regulable attenuation module, including angular measure setting, beam splitter, energy meter, attenuator and simulant target, was designed and founded.The analysis of data and uncertainty of the test upon different simulant target properties and atmospheric condition has proved that noncooperative regulable attenuation method and setting described in the paper can achieve a quantitative output. The accuracy can be better than ?0% with relative fine atmospheric condition. The method and setting has been adopted by the spaceborne laser altimeter for 200km maximum range and the result is about 100km. Based on the analysis of each parameter's effect, the reason for the altimeter's not satisfying the requirement was analyzed.