COLLIMATING AIRCRAFT 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 a flat reflecting mirror, and a two-component semitransparent inclined mirror, located above the lens. The first component is made from a first negative meniscus and second and third positive meniscuses, whose concave surfaces face the screen of the CRT. The second component is a positive meniscus, the concave surface of which faces the reflecting mirror. The following ratios are satisfied: 2f > L > 1.7f, d > 1.1f, 1.75 > n₂, n₃ > n₁ > n₄ > 1.5, R₁ < R₃ < R₅, R₈ > 1.1f, where f is the focal length; L is the length of the lens; d is the distance between the first and second components; n₁, n₂, n₃, n₄ is the refractive index of the first, second, third and fourth lenses respectively; R₁, R₃, R₅, R₈ are values of radii of the first surfaces of the first, second, third lens and the second surface of the fourth lens, respectively.

EFFECT: wider field of vision.

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