An apparatus has a rangefinder portion that includes: a radiation generator which emits radiation having a selected wavelength; a radiation detector which detects radiation having the selected wavelength; and an optical portion which includes a non-reciprocal optical part. The optical portion routes radiation emitted by the radiation generator at the selected wavelength through the non-reciprocal optical part and then through an aperture toward a location remote from the apparatus, and also routes radiation received via the aperture at the selected wavelength through the non-reciprocal optical part and then to the radiation detector.