WIDE-ANGLE COLLIMATING INDICATOR Russian patent published in 2009 - IPC G02B27/18 G02B27/01 

FIELD: physics; optics.

SUBSTANCE: proposed indicator contains a cathode ray tube (CRT), a two-component lens, between the components of which there is an optical element, breaking the optical axis, made in form of flat reflecting mirror, inclined to the axis of the CRT, and a two-component semitransparent inclined mirror located above the lens. The first component of the lens is made from two positive lenses, the first of which is made from a positive and a negative meniscus stuck together and the second is from a positive lens and a negative meniscus. The second component is a plane-convex lens, the convex surface of which is parabolic. The following ratios are satisfied: 1.9 > n₁, n₄ > n₂, n₃ > 1.6 > n₅, 1.1f > R₈ > f, f > d > 0.9f, 2f > L > 1.6f, where: n₁, n₄, n₂, n₃, n₅ are refractive indices of the first and second negative meniscuses, positive meniscus, third lens and fifth plane-convex lens, respectively; f is the focal length of the lens; R₈ is the radius of the second surface of the second component; d is the distance between the components of the lens; L is the length of the lens.

EFFECT: wider instantaneous field of vision.

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