An optical system particularly suited for non-linear fluorescence collecting includes a front lens system, a rear lens system, and a bulk, dichroic beam splitting component intermediate the front lens system and the rear lens system to direct the fluorescent emission from a target object to a photodetector. A lens housing may have a reflective coating on an interior surface thereof. The objective optical system is particularly advantageous for use in cases where large fields of view and high collection efficiencies are desirable.
