Distortion Measurements on Antenna Dishes Under Space Simulation Conditions

Two methods for measuring thermal distortion of antenna dishes under simulated space conditions are described:

Photogrammetry

Holography

With modern photogrammetry an absolute resolution of 20 μm at 1 σ for antenna dishes with a diameter of 1 to 3 m can be achieved. Statistical methods are used to evaluate the 10 to 30 pictures of the test item which are taken from different positions.

Double exposure holography has as an interferometric method a much higher resolution in the order of 20 nm to 100μm. But only differences between two shapes will be measured and only in one direction.

Both methods are used in our space simulation facility WSA/TVA and several tests are successfully performed.