Design studies for nonimaging light concentrators to be used in very high-energy gamma-ray astronomy

Light concentrators to be used by the camera of a telescope to view gamma-ray-induced Cherenkov light, are analyzed from the point of view of optical efficiency, background rejection capability and manufacturability. A small decrease in the optical efficiency due to multiple reflections undergone by rays incident at small angles in a compound parabolic concentrator is observed. The influence of the angle of incidence on the reflectivity of the wall is analyzed and found to be inconsequential. A closed-packed matrix of concentrators with hexagonal entrance apertures is considered and the light spread in the adjacent pixels introduced by the removal of portions of the surface of concentrators is evaluated.