A method and apparatus for aligning optical components within an optical sensor. A mask with an elongate slot formed therethrough is placed optically between an optical emitter and an optical detector of the sensor. The mask is rotated 180 degrees while the detector output is measured. As the mask is rotated, the output varies. The longitudinal position of the slot that corresponds with the maximum detector output is indicative of the transverse direction that the optical emitter must be moved relative to the optical detector for optimal alignment. A controller may operate a first actuator for translating the optical emitter with respect to the optical detector and a second actuator for rotating the mask, thereby automating the alignment process.