Patent ID: 9638900
Date: 2017-05-02
CPC Classifications: G02B

Claim:
1. An optical instrument comprising: an optical arrangement of lenses associated with a back focal plane and further comprising a first, a second, a third, a fourth, a fifth, and a sixth lens ordered from first to sixth along a common optical axis such that the first lens is farthest from the back focal plane and the sixth lens is closest to the back focal plane, wherein the first and the second lenses are made of zinc sulfide, the third and the sixth lenses are made of barium fluoride, the fourth lens is made of magnesium oxide, and the fifth lens is made of calcium fluoride, and wherein the lenses are selected to transfer any light within a wavelength range that contains 0.42 μm to 3.6 μm, and wherein the lenses are located in specified locations along the common optical axis and are further associated each with specified radii, wherein the specified locations and the specified radii are further selected such that the optical arrangement has a focal length of between 12 mm to 20 mm and a back focal length greater than 20 mm, wherein the optical arrangement of lenses has an f-number of 0.7 to 1.4.