Collimators enable long-range testing to be performed in a compact environment.  The relay lens elements produce a virtual image of a target focused at a long distance. Typically these are focused around the hyperfocal distance or up to infinity.

Collimator lenses require a test chart and light source in order to make a complete target projection systems. Target projection collimators include these targets in the form of high-precision circular reticles and light sources.

These assemblies need to be aligned precisely with the entrance pupil of the camera under test in order to produce an appropriate image for testing.