Transportable lunar-ranging system

Ruby lasers in large, fixed installations are being used by groups in France, Japan, the Soviet Union, and the U.S. for measuring distances to retroreflectors on the moon. This paper describes a transportable transmitting unit that can be installed at any astronomical observatory where a large telescope is available to detect the received signal. The transmitter consists of a high radiance, frequency-doubled, neodymium-glass laser and a coudé optical system of moderate size. It has been installed, but is not yet in operation, at the Agassiz Observatory, Harvard, Massachusetts.