Patent ID: 7050223

Claim:
A DUV-capable microscope objective, comprising: a plurality of lens elements, on an object side, to generate convergent light; a penultimate lens element which receives the convergent light from the plurality of lens elements; and a further lens element, on an image side, which receives light from the penultimate lens element; wherein the plurality of lens elements and the further lens element are made of quartz glass and fluorite and the penultimate lens element is made either of quartz glass and fluorite or of quartz glass and lithium fluoride, the objective has a DUV focus at a DUV wavelength λ DUV , wherein λ DUV is one wavelength in the deep ultraviolet region between 200 nm and 300 nm, the objective has an IR focus for an IR wavelength λ IR , wherein λ IR is one wavelength in the infrared region greater than or equal to 760 nm, at the same focal point as the DUV focus at λ DUV , and the penultimate lens element comprises a concave configuration on both sides, wherein an object-side radius of curvature of the penultimate lens element is smaller than its image-side radius of curvature.