Patent ID: 7646472
Filing Date: 2010-01-12
Classification: G03F

Abstract:
1. An off-axis illumination apparatus, comprising: a mask stage configured to support a mask including a transparent substrate, formed of a transparent material, and a plurality of opaque layers disposed on the transparent substrate to be mounted to the mask stage; a light source configured to emit light to the mask; an incident angle varying section configured to move at least one of the light source and the mask stage to vary an incident angle of the light on the mask; a first driver configured to rotate the mask stage to vary the incident angle of the light on the mask; a second driver configured to move the light source to vary the incident angle of the light on the mask; a selector configured to select one of the first and second drivers; an optical detector configured to detect an amount of light transmitted through a rear surface of the mask; and a controller configured to control an operation of one of the first and second drivers selected by the selector, and to receive the detected amount of light from the optical detector in order to determine whether the detected amount of light is equal to a preset amount of light.