Patent ID: 7388652
Filing Date: 2008-06-17
Classification: G03F

Abstract:
1. A radiation distribution measurement system configured to measure a phase distribution of a beam of radiation and/or a pupil distribution of a projection system, the measurement system comprising: a transparent carrier plate; a grating and/or a pinhole configured at a first side of the transparent carrier plate; a camera having a sensitive element configured at a second side opposite the first side of the transparent carrier plate; and a radiation filter configured between the transparent carrier plate and the camera, the radiation filter having a transmissivity that is lowest at the center of the filter and gradually and concentrically increases towards the outside of the filter, and the radiation filter is arranged to transmit toward the sensitive element radiation from an optical system having a numerical aperture of about 1 or greater, and to achieve approximately uniform signal to noise ratio for substantially all portions of the sensitive element of the camera.