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Infrared filter

  • US 9,575,231 B2
  • Filed: 09/13/2013
  • Issued: 02/21/2017
  • Est. Priority Date: 09/02/2013
  • Status: Active Grant
First Claim
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1. An infrared filter comprising:

  • a transparent substrate; and

    an infrared-filtering multilayer film, wherein the infrared-filtering multilayer film is coated on the transparent substrate, and the infrared-filtering multilayer film comprises;

    a plurality of the first kind of film layers;

    a plurality of the second kind of film layers;

    a plurality of the third kind of film layers; and

    a plurality of the fourth kind of film layers;

    wherein the infrared-filtering multilayer film is wave-like arranged with the four kinds of film layers in order of gradient refractive indexes, a thickness of any of the first kind of film layers is greater than a thickness of any of the second kind of film layers and a thickness of any of the third kind of film layers, a thickness of any of the fourth kind of film layers is greater than the thickness of any of the second kind of film layers and the thickness of any of the third kind of film layers, at least two kinds of film layers are made of composite materials, which are made of Nb2O5 and SiO2, a refractive index of the first kind of film layers is NA, a refractive index of the second kind of film layers is NB, a refractive index of the third kind of film layers is NC, a refractive index of the fourth kind of film layers is ND, a total number of the film layers of the infrared-filtering multilayer film is TL, a decay rate of transmittance responsivity value through the infrared filter between 554 nm and 700 nm is D, and the following conditions are satisfied;


    2.2

    NA<

    2.4;


    1.9

    NB<

    2.2;


    1.6

    NC<

    1.9;


    1.4

    ND<

    1.6;


    80

    TL
    ; and


    1%≦

    D≦

    30%.

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