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Image input apparatus

  • US 5,875,025 A
  • Filed: 07/14/1997
  • Issued: 02/23/1999
  • Est. Priority Date: 07/15/1996
  • Status: Expired due to Term
First Claim
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1. An image input apparatus comprising:

  • a first fiber optic plate in which a plurality of optical fibers are bundled together, said first fiber optic plate having an entrance surface inclined with respect to an optical axis of said each optical fiber by a predetermined slant angle θ

    0 and an exit surface opposing said entrance surface;

    a light source for illuminating said entrance surface; and

    a holding member for holding said light source at a predetermined position, said holding member holding said light source in a state where, of incident angle components formed between a luminous flux emitted from said light source and said entrance surface, a vertical incident angle component θ

    V on a plane orthogonal to a reference end on said entrance surface, said reference end defining said slant angle θ

    V, is set to a range deviating from a range of stray light admissible angle X given by the following expression;

    
    
    space="preserve" listing-type="equation">(X.sub.C -Θ

    )≦

    X≦

    (X.sub.C +Θ

    )wherein;

    XC is a stray light admissible center angle given by an expression (90°

    -sin-1 (ncore ·

    sin(90°

    -3θ

    0)));

    ncore is a refractive index of a core in said each optical fiber;

    θ

    0 is the slant angle;

    Θ

    is a total reflection critical angle in the air given by an expression (sin-1 (ncore ·

    sin(90°

    -SC

    )));

    SC is a stray light admissible center angle in said each optical fiber given by an expression (sin-1 ((1/ncore

    sin XC));

    φ

    is a total reflection critical angle in said each optical fiber given by an expression (sin-1 (nclad /ncore)); and

    nclad is a refractive index of a cladding in said each optical fiber.

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