Patent ID: 7138640

Claim:
An inspection system for detecting defects on a sample, the inspection system comprising: an optical subsystem configured to collect ultra violet light emanating from the sample, the optical subsystem including an optical component having an optical surface; a detector configured to receive the collected light from the optical subsystem and to generate an image of at least a portion of the sample with the received light; an analyzer configured to determine whether there are any defects present on the portion of the sample by analyzing the image generated by the detector; and a gas purge system configured to produce a gas stream that blocks contaminants from reaching the optical surface of the optical component and that transports the contaminants away from the optical surface of the optical component, the gas purge system including a substantially planar cover having an opening disposed in front of and along an optical axis of the optical component, the opening allowing light to pass for the purpose of inspecting the optical surface of the optical component, and the gas stream to pass for the purpose of preventing contaminants from reaching the optical surface of the optical component.