HIGH-APERTURE INFRARED LENS Russian patent published in 2023 - IPC G02B13/14 G02B9/34 

FIELD: optical instrumentation.

SUBSTANCE: special lenses operating in the IR wavelength range. The lens is high-aperture infrared and contains four components, of which the first, the third, and the fourth are positive menisci with their concave surfaces facing the image plane, the second component is a negative meniscus with the convex surface facing the image plane. The first, the third, and the fourth components are made of germanium, i.e. the following relations are satisfied: n₁=n₃=n₄, v₁=v₃=v₄, where n and v are the refractive indices and the dispersion coefficients of the components, respectively, the second component is made of zinc selenide. In this case, the relative optical powers of the components and the air gaps satisfy the following conditions: F₁=(0.42÷0.47)F, F₂=-(0.066÷0.076)F, F₃=(0.25÷0.27)F, F₄=(1.16÷1.34)F, d₂=(0.37÷0.44)/F, d₄=(0.39÷0.44)/F, d₆=(0.39÷0.44)/F, where: F₁, F₂, F₃, F₄ - optical powers of the first, the second, the third, and the fourth components, respectively; F - optical power of the lens; d₂, d₄, d₆ - air gaps, respectively, between the first and the second, the second and the third, the third and the fourth components.

EFFECT: increase in the focal length of the lens and the linear field of view with high image quality.

1 cl, 4 dwg, 3 tbl