ILLUMINATING SYSTEM, ALIGNER AND DEVICE MANUFACTURE

PROBLEM TO BE SOLVED: To constantly illuminate a plane to be illuminated with a stable illuminance, by detecting the temperature of a illuminance sensor, and cooling the illuminance sensor based on the detected temperature so as to maintain the temperature of the illuminance sensor at a prescribed value. SOLUTION: A differential amplifier 32 amplifies a signal provided based on a difference between a signal from an illuminance sensor 1 and an instruction signal from an illuminance instruction part 33, which outputs the signal for previously setting the illuminance on the plane of a subject to be illuminated, and outputs it as a power control signal. The power control signal from the differential amplifier 32 is converted into power by a lighting device 31, and the light emitting quantity of a lamp 11 is controlled. A heat dissipating tin 2 is mounted on the rear plane of the illuminance sensor 1, and temperature increase of the illuminance sensor 1 is suppressed. The illuminance sensor 1 is provided with a temperature sensor 4, and temperature change is fetched to a temperature control part 5. The temperature control part 5 controls the rotating speed of a fan 3 through a rotating speed control part 6 so as to have the temperature of the illuminance sensor 1 within a set range.