Patent ID: 6992834

Claim:
An objective with first birefringent lenses and with second birefringent lenses, wherein the first lenses are distinguished from the second lenses by a lens material used or by a material orientation, wherein a bundle of light rays originates from an object point with an outer aperture ray and a principal ray that have a wavelength and, in each of the lenses, an aperture angle, wherein in each of the first lenses and in each of the second lenses the outer aperture ray and the principal ray are subject to an optical path difference for two mutually orthogonal states of polarization, said optical path difference being dependent on at least the aperture angle in the respective lens, wherein after passing through the first lenses and the second lenses, a difference between a total optical path difference of the outer aperture ray and a total optical path difference of the principal ray for two mutually orthogonal states of polarization is smaller than 25% of the wavelength, wherein in at least one of the first lenses, the aperture angle of the outer aperture ray is at least 70% of the largest aperture angle occurring for said outer aperture ray in all of the first and second lenses, and wherein the first lenses have a combined material volume of no more than 20% of the combined material volume of all of the first and second lenses.