PHOTOGRAPHIC TELEPHOTO LENS Russian patent published in 2018 - IPC G02B13/02 G02B9/62 

FIELD: optics.

SUBSTANCE: telephoto lens can be used in optoelectronic devices that form images of objects of the earth's surface through the real atmosphere and working with photodetectors of the visible and near-IR range. Telephoto lens contains two groups of lenses, in the first group an aperture diaphragm is located between the first and second lens, second lens is a negative meniscus facing the bulge to the object, the third is the positive meniscus facing the bulge to the object, the fifth is the negative meniscus, which is convex toward the object, with the possibility of moving along the optical axis. Second group of lenses is a biconvex lens. Following ratios are met: Δl_1g5L≤0.02∙f'_lens; n₁=n₃≤n₄≤n₂≤n₅=n₆, where Δl_1g5L – the amount of movement along the optical axis of the fifth lens in the first group of lenses; f'_lens – focal length of the lens; n_1,2,3,4,5,6 – refractive indices of materials of the 1^st, 2^nd, 3^rd, 4^th, 5^th and 6^th lenses, respectively.

EFFECT: increase in aperture while maintaining acceptable image quality in the near IR-range in the extended temperature range.

1 cl, 1 dwg, 1 tbl