Patent ID: 8345350
Filing Date: 2013-01-01
Classification: G02B,G03B,G03F

Abstract:
1. An objective comprising: a plurality of optical elements arranged to image a pattern from an object field in an object surface of the objective to an image field in an image surface region of the objective at an image-side numerical aperture NA>0.8 with electromagnetic radiation from a wavelength band around a wavelength λ, the optical elements including a number N of dioptric optical elements, each dioptric optical element i made from a transparent material having a normalized optical dispersion for a wavelength variation of 1 pm from a wavelength λ 0 , wherein the objective satisfies: for any ray of an axial ray bundle originating from a field point on an optical axis in the object field; where s extends on all dioptric optical elements of the objective, and where