A phase-compensating cube comer retroreflector includes three rear reflecting surfaces. All three rear reflecting surfaces can be coated with a phase-compensating film stack that induces 2n.pi. phase difference when handling polarized light. So coated, the phase-compensating cube comer preserves the polarization orientation and ellipticity of the incident light. Such a phase-compensating cube comer can be used to improve the accuracy of distance-measuring interferometers. The cube corner directs light to and from other optical elements, including a polarizing beam-splitters, mirrors, and quarter-wave plates.