Short Wavelength Annular Field Optical System for Imaging Tenth Micron Features.

We have found that the 1:1 Offner annular-field system can provide high resolution imaging in the extreme-ultraviolet (XUV) when used at numerical apertures (NAs) around 0.1. For example, when illuminated with radiation at wavelengths shorter than 15 nm, a 0.0835 NA system with a 233.6 mm diameter primary mirror should be able to image 0.1micron lines and spaces in a 100micron wide 50 mm radius ring-shaped field at high contrast.