REFLECTIVE PRISM DEVICE

PROBLEM TO BE SOLVED: To allow good data communication between a measuring device and a reflective prism device even with a measurement at such near distance as no expansion of optical flux takes place, related to a measuring device comprising a function wherein information is optically transferred using optical modulation, etc. SOLUTION: A prism part 3 and data communication part 4 are provided, and a communication beam is irradiated from a measuring device toward the prism part 3. Here, a light guide 26 which guides a part of the communication light incident on the prism part 3 to a data communication part 4 is provided, so even when the data communication part 4 cannot receive the communication light as the expansion of a range finding optical flux is not sufficient with the measuring device close to the reflective prism device, the communication light is guided to the data communication part 4 by the light guide 26 for optical information transfer.