An apparatus for concentrating light and associated method of use is disclosed. This apparatus includes a first outer wall having an anterior end, a posterior end, an inner surface and an outer surface, the inner surface defining an interior portion, the interior portion having an anterior end and a posterior end, and a light source disposed within the interior portion. The first outer wall has an opening in the posterior end, the opening having an opening diameter. The interior portion has a substantially frusto-conical shape and has a cross-sectional diameter at the opening equal to the opening diameter and a second cross-sectional diameter near the anterior end that is less than the opening diameter and the inner surface is photo-reflective. The light passes through a sample through an aperture and a collector lens or a second outer wall. A transmission diffraction grating may be utilized.