Laser reflector
As a laser reflector , a is an optical system referred to, the incident laser beam reflects the light source. The reflections from laser reflectors are mainly used to measure the transit time and distance.
The laser reflectors are usually composed of numerous small triple mirrors - optical prisms that reflect each incident beam in themselves. They have a similar principle as the cat's eyes - reflectors in traffic engineering, but are much more accurate ground (to a few arcseconds exactly or better) to the close bundling obtain the laser beam.
In geodesy , laser reflectors have been used since the 1980s instead of the previously common measuring rods and, with modern total stations, allow automatic targeting of the measuring points and distance measurements accurate to the millimeter . The standard reflectors are a few centimeters in size and reach several hundred meters. Several prisms can be stacked on top of one another for greater distances.
In satellite geodesy , reflection technology is used for time of flight measurements by means of satellite laser ranging (SLR for short), with which high-precision satellite orbits can be determined. SLR is the most accurate method for global surveying networks , such as monitoring the earth's rotation and gravity .
The first satellites equipped with reflectors were Explorer 19 and Diadems, the cut angles of which even included the aberration of the light. Among the 20 or so active SLR satellites, the two American LAGEOS satellites are the largest, with 426 reflectors embedded in their spherical surface. The French Starlette satellite is also important .
For purposes of astronomy were from 1969 to 1972 by the Apollo missions some laser reflectors on the US Moon sold to the lunar laser ranging to enable and fine changes in the moon's orbit to capture. They are about 0.5 meters in size, five of them still give sufficient light echoes. Between 1970 and 1973, the USSR brought Lunochod 1 and Lunochod 2 equipped with laser reflectors to the moon, which in 2010 still reflected light echoes.