JPL self-pulsed laser surface measurement system development

Distances from a fixed reference or scan postion to several locations on the surface of an antenna reflector can be measured by using a self pulsed laser ranging system. Processing the information thus obtained is used to define the shape of the surface upon which antenna operational efficiency is directly dependent. Operation of the system consists of initiating a pulse from the laser emitter which is pointed at the scan mirror. The emitted pulse strikes the scan mirror, is reflected and sent to one of several targets on the surface of the antenna. Upon reflection from the target, the pulse returns to a detector via the scan mirror. The detected pulse is amplified and used to trigger the next emitted pulse. After the first pulse is emitted, received and used to trigger another pulse the process becomes repetitive with a repitition rate uniquely determined by the distance traveled to the target and back. A measure of the repetition rate or frequency thus created provides the means required for determining range since the total distance traveled is inversely proportional to the frequency.