A device and method for operating a lighting system varies a characteristic of visible light emitted by a first lighthead according to a predefined profile, and fixes a characteristic of visible light emitted by a second lighthead. A light sensor configured to view a focal area of the second lighthead detects a characteristic of visible light on a target surface over a period of time, and the characteristic of the light detected by the light sensor over the period of time is compared to the characteristic of light defined in the predetermined profile. A mode of operation of the first and second lighthead is determined based on the comparison.