A retroreflector (a device that reflects an incident beam of light through exactly 180 degrees ) constructed from a primary concave mirror and a small secondary mirror near its paraxial focus, the so-called cat's-eye retroreflector, has been investigated. Ray-tracing of systems with both spherical and parabolic primaries suggests that the latter are considerably superior to the former and comparable to a cube-corner retroreflector. The investigation has also enabled mechanical tolerances for the construction of a cat's-eye retroreflector to be deduced. The predicted tolerances may be much easier to attain than those for a cube-corner retroreflector.
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Beer et al. (1966) studied this question.