An optical unit includes a plurality of paraboloid mirrors configured to reflect light fluxes from a plurality of LDs and to guide them to a concave lens. The shock absorber body is mounted on the intermediate element of the hinge. A releasable attachment member can releasably secure the housing to the skin surface, for example, with an adhesive bond. In one embodiment, the interference detection module generates an interrupt for a processing system when the power level associated with the interference signal is greater than the threshold value. The same starter unit design is usable both in single-lamp fixtures and in multi-lamp fixtures where a mix of ballast types may be used.