A light sensor for an ultraviolet lamp system of the type having an electrodeless lamp excited by microwave energy includes a detector configured to detect light generated by the electrodeless lamp. An elongated channel is configured to be interposed between the detector and the electrodeless lamp. The elongated channel has a first aperture and a second aperture defined at opposing ends thereof. The first aperture is configured to receive light generated by the electrodeless lamp. The second aperture is positioned proximate the detector to transmit at least a portion of light received in the first aperture to the detector.