Investigation vignetting beams in optoelectronic autocollimation angle measurement system

Autocollimation systems are widely used to measure angular values, in particular, angular deformations in the critical points of large objects, angles of optical components, and for controlling the straightness and parallelism. Autocollimator measures the rotation angle of the mirror as the sensitive element at angular deformation point with a potential accuracy up to 0.005 ''. In fact, the error may significantly exceed the specified value because of systematic error existence, one of which main components is the error due to vignetting of working beam. The reason of vignetting error is changing of irradiance distribution of the image on the autocollimator analyzer due to cutting of a bundle of optical beams at a mirror deviation in case of angular deformation. On the basis of a computer simulation image model was investigated the influence of vignetting error and was found compensation algorithm of this error