Abstract: An irradiator includes an elongated housing having an interior recess opening outwardly along a longitudinal length of the housing. A plurality of generally planar relatively thin ribs are supported within the recess substantially transverse to the longitudinal axis of the housing and define laterally spaced substantially symmetrical contour surfaces operative to support reflector members. The ribs are readily interchangeable to support reflector members so as to establish generally parabolic, semi-circular or elliptical reflector profiles. A pair of lamp holder assemblies are supported within the housing recess for supporting a source of light energy, such as an elongated ultraviolet light bulb, intermediate the contour surfaces to enable focused or nonfocused irradiation of energy. In one embodiment, shutters as provided to substantially preclude irradiation when in closed positions.