Image magnification and distortion

A collimator is like a telescope in reverse. So rather than looking at or taking an image in the focal plane, a collimator has a light source there which is projected into the far-field and acts like an artificial star. In this way a camera or optical system illuminated by the plane wave emitted from our 30 cm diameter collimator can be accurately checked for its image quality. In addition to point sources we also have geometrically calibrated patterns. The wavefront quality of the output beam from the collimator is lambda/50 at 633 nm.