NIGHT VISION DEVICE Russian patent published in 2009 - IPC G02B23/12 

FIELD: physics.

SUBSTANCE: night vision device has an objective, an electro-optical converter (EOC) and an ocular system (OS). The objective is in form of four components, the first of which is a positive convex-concave lens, the second - a group of two negative lenses, the third - a positive biconvex lens, the fourth - a group of three lenses, the first of which is a positive biconvex lens, the second - a negative biconcave lens, and the third - a positive convex-concave lens. The second component can be moved relative the photocathode of the electro-optical converter to provide for smooth variation of the equivalent focal length of the objective from the minimum to the maximum value without changing position of the plane of the best installation relative the photocathode of the electro-optical converter. The fourth component can be moved relative the photocathode of the electro-optical converter so as to compensate shift of the plane of best installation at intermediate positions of the second component, where the maximum value of its displacement Δd11_max≤5S_max, where ΔS_max - is the maximum value of longitudinal spherical aberration in the working spectral range, and its additional displacement determines the near focal length.

EFFECT: possibility of usage when making night vision devices in very diverse operating conditions.

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