• THE GERMAN LIDAR PROJECT

  • ASA Mirror mount for high precision laser measurements in the atmosphere


    The company ASA Astrosysteme is specialized in manufacturing high precision optical guidance systems and also engages in custom made projects for scientific applications. In collaboration with the Karlsruher Institute of Technology (Institute of Meteorology and Climate Research – Research of the Atmosphere – IMK-IFU) ASA has implemented a software controlled and highly precise mirror mount for a rerouting mirror for the new LIDAR project on the Zugspitze (Mountain with 2962 Meters) in Germany. The diameter of the mirror is close to 0,5 Meters (20 inches) in order to accommodate and redirect loss-free and at a 90 degree angle a high performance laser beam (350 W at 208 nm wavelength) bloated to approx. 0,3 Meters diameter (12 inches) vertically into the atmosphere.

    Lidar (Light detection and ranging) is a method to determine distance- and speed measurements with a strong laser, but is also a method to detect atmospheric parameters from a distance. The instrument sends out laser impulses and detects the returning straight light in the air. Judging from the duration of the signals and the speed of light the distance to the object can be accurately measured.

    ASA Astrosysteme contributed to the project with the construction of a Mirror mount featuring the possibility of angular adjustments: The mount allows a motorized movement of the heavy 500mm flat mirror for about +/- 3 degrees in Azimuth and Elevation. The movement can either be controlled via Software (developed by Phys. Philipp Keller) or through the input of a hand panel. The program allows for individual parameterizations of different settings such as: speed, resolution, angle and end stop.

    Based on these controllable parameters, a laser beam directed into the atmosphere can be directed precisely parallel to the vertically aligned axis of the receiving telescope. The telescope on the Zugspitze has a particular large main mirror with a diameter of 1.5 m (Keller). In combination with a high performance laser very sensitive measurements of water vapor (the primary greenhouse gas) can be measured for the first time up to 30km and temperature readings can be conducted up to 100km into the atmosphere.

    The project was funded through resources allocated by the Bavarian Agency for the Environment.

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