OPTICAL SYSTEM FOR IR SPECTRAL REGION (VERSIONS) Russian patent published in 2008 - IPC G02B13/14 G02B9/64 

FIELD: optics.

SUBSTANCE: optical system contains lens forming true intermediate image, containing first positive lens and positive meniscus concave to image, projection lens, containing first two lenses with common positive focal power, third positive lens and fourth positive meniscus concave to image, and true offset exit pupil. In the first version negative lens with second concave surface is introduced into lens after positive meniscus. And projection lens contains first positive lens with second convex surface, second negative lens with first concave surface and third lens with first convex surface. In the second version negative lens is introduced into lens before positive meniscus with first concave surface, and projection lens is executed as in the first version. In the third version negative lens is introduced into lens after positive meniscus with second concave surface and projection lens contains first negative lens with second concave surface, second positive lens with second convex surface. In the fourth version negative lens is introduced into lens before positive meniscus with first concave surface and projection lens is executed as in the third version.

EFFECT: higher aperture ratio of optical system for IR spectral region with true intermediate image and true offset exit pupil.

4 cl, 4 dwg