Patent ID: 7422988

Claim:
An apparatus for thermal processing of a substrate, comprising: a source of laser radiation emitting light at a laser wavelength; an optical system disposed between the source and the substrate to receive light from the source for thermal processing of the substrate, wherein the optical system comprises a plurality of optical elements; a housing for holding the optical system therein, wherein the laser light radiation is maintained therein at a predetermined level, and wherein deterioration of at least one optical element of the optical system causes the light radiation within the housing to exceed the predetermined level; a light detector disposed inside the housing for detecting the excessive laser light radiation within the housing by examining whether the radiation within the housing exceeds a predetermined reference level, and generating a control signal upon detection of the excessive laser light radiation; a power supply to generate power to the source of laser light radiation; a controller to control the power supply based on the control signal from the light detector; and a translation mechanism to move the light detector within the housing relative to the optical system.