Abstract: An improved, low-cost optical transmitter and method useful in a three-dimensional measurement system wherein a plurality of operational parameters of said transmitter are calibrated during manufacture/assembly process to generate unique calibration data for each optical transmitter including data defining angles of each transmitter's first and second radiant fan beams and the angle between the beams when the transmitter is leveled for operation in the system and wherein a detector/receiver in the system distinguishes between radiant beams from a plurality of individual transmitters operable within a given measurement field as a function of the selectively alterable rotational velocity calibration data for each of said transmitters and wherein said angular calibration data for each transmitter is operationally available to each detector/receiver operable in the system.