Patent ID: 9383565
Filing Date: 2016-07-05
CPC Classification: G02B

Claim Text:
1. A tube lens unit for a microscope, the tube lens unit having an achromatically corrective effect and the tube lens being for the use with objectives image an object to infinity and that have achromatic residual errors, the tube lens unit including at least two lenses including a positive lens and a negative lens with the properties wherein n P and n N signify the refractive index n e at a wavelength of 546 nm for the positive and the negative lens respectively, and v P and v N signify the Abbe number v e at a wavelength of 546 nm for the positive and the negative lens respectively, and ray paths are characterized by conditions as follows: wherein δA signifies the variation of an aperture ray as penetration heights for a diameter of the entrance pupil EP of 17.55 mm while passing through surfaces of the two lenses and δB signifies variation of a main ray as penetration heights for an incidence angle w=3.23 degrees while passing through the surfaces of the two lenses.