Method for reducing the resolution of an aerial image of a photolithography mask without reducing a signal-to-noise ratio and corresponding optical system

Abstract

The invention relates to an optical system and a method for reducing the resolution of an aerial image of a photolithography mask without reducing a signal-to-noise ratio, the method comprising: acquiring an aerial image of the photolithography mask using an optical system, in which structures of the photolithography mask are illuminated by a light source and projected onto an image sensor of a camera by use of projection optics, thereby generating an aerial image, wherein a pixel size of the image sensor of the camera is below a Nyquist limit defined by the resolution limit of the optical system; applying an anti-aliasing filter to the acquired aerial image; and downsampling the filtered aerial image to obtain an aerial image of reduced resolution.

Dependencies are inferred from the claim text.