Multidirectional retroreflector assembly with a common virtual reflection point using four-mirror retroreflectors

A brief survey of retroreflector designs and applications is presented. A novel multidirectional (as opposed to omnidirectional) retroreflector concept is proposed by the author. A practical four-mirror retroreflector subassembly with a common virtual reflection point (thus eliminating the Abbe error), is described. Applications include: multilateration with interferometers, laser trackers, and electronic distance measurement surveying instruments; hidden point measurements to inaccessible locations; an extension of the concept to include optical targets for theodolite work; and an extension to other radiation sources, e.g., microwaves and acoustics. Example configurations are given.