Do you mean sweeping a laser across the moon to try and get a topographic map that would show a lander? If so, I don't think a laser would provide that kind of detail. Check out the following site about measuring the distance to the moon using a laser.

http://www.lpi.usra.edu/expmoon/Apol...ents_LRRR.html

Particulary this paragraph.

"Laser beams are used because they remain tightly focused for large distances. Nevertheless, there is enough dispersion of the beam that it is about 7 kilometers in diameter when it reaches the Moon and 20 kilometers in diameter when it returns to Earth. Because of this very weak signal, observations are made for several hours at a time. By averaging the signal for this period, the distance to the Moon can be measured to an accuracy of about 3 centimeters (the average distance from the Earth to the Moon is about 385,000 kilometers)."

There is also a neat pic of the laser at the top of the page.

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