reflector 53 3 being located at unity focal length f1 like the first embodiment each reflector 53 may comprise a plane mirror 52 mounted on an adjustable mirror mount 54 after being directed by rotary actuator scanner mirror 43 onto a selected one of the three mirrors 53 1 53 2 53 3 and an associated one of the reflectors 63 1 63 2 63 3 of reflector array 63 the beam is reflected from the back side 44 of rotary actuator mirror 43 through second focussing lens 52 as described above focussing lenses 51 and 52 provide a matched entrance and exit lens pair that focus and collimate the beam in operation similar to the first embodiment if the total distance from lens 51 along the triangular beam travel path to lens 52 is unity focal length there is no change in the diameter of the beam and is the beam simply recollimated by lens 52 however any other triangular travel path distance will cause lens 52 to produce a diverging beam advantages of the embodiment of fig2 include the elimination of broadband optical isolators which are costly and a potential increase in efficiency however because of the additional geometry path considerations the triangular arrangement of fig2 is optically more complex than the embodiment of fig1 and requires more alignment the embodiment of fig2 may be modified by replacing the plane mirrors 53 and 63 used in the offset triangular path with spherical mirrors thereby.