Retroreflector Cube

A retroreflector cube is a special optical component composed of three mutually perpendicular reflecting surfaces. Its core characteristic is that regardless of the angle of incident light, it can return the light along the original incident direction through three reflections, achieving a 'retroreflection' effect. This property makes it widely used in scenarios requiring precise light path control or target positioning, such as laser ranging, astronomical observation (e.g., measuring Earth-Moon distance in the Apollo program), optical communication, calibration of measuring instruments, and some optical sensing and imaging systems.