An optical system is adapted to produce reduced back reflection from a receiving detector back to a light source for increased system performance. The system may optically condition light signals from the light source for projection onto the detector. The conditioning may result in a light spot on the detector that has an annular intensity distribution or profile. The annular distribution may be attained in any number of ways including providing a slope discontinuity in the lens surface, providing an ax icon lens function, and/or providing a defocused light spot on the detector surface.