Status and Possible Improvement of Lunar Laser Ranging

Lunar Laser Ranging (LLR) is a great goal in the world and it represents the height of the single photon detection. The status of the lunar laser ranging and its difficulties are introduced in this paper. We also introduce some possible improvement methods that we proposed for increasing returned photon numbers on the LLR. A new idea is introduced especially that uses a small area near the retroreflector array on the moon surface as an extended source to detect and calculate the wavefront tilt, and then carry on the real-time tilt compensation for the laser beam on the LLR. Finally, Yunnan Observatory Laser Ranging System and its goal are introduced.