Light beam heating apparatus with optical energy correction compensating for lamp electrode wear and aging

Abstract

A photosensor arranged at the center of a light-receiving end of an optical fiber bundle detects an optical intensity which is converted by a photoelectric converter to an electric signal. Then, the optical energy provided at the optical fiber bundle is calculated based on the signal. On the other hand, a correction coefficient is calculated from optical intensity signals when the lamp is new and when the element in the lamp wears, and the setting value of the output optical intensity of the optical fiber bundle is corrected. Then, the current supplied to the lamp by a power supply is controlled according to a difference between the setting value and the measured optical energy. Thus, the optical energy to be received through the optical fiber bundle is controlled stably irrespective of the change of optical intensity distribution due to wear of the electrode of the lamp. Similarly, the correction coefficient is calculated from optical intensities measured with photodetectors arranged at and off the center of a light-receiving end of an optical fiber bundle.

Dependencies are inferred from the claim text.