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Dielectric multilayer filter

A filter and dielectric technology, which is applied in the field of dielectric multilayer filters, can solve problems such as changes in the color of reflected light, and achieve the effect of reducing the width of the reflection band and reducing the dependence of the incident angle

Inactive Publication Date: 2008-01-16
MURAKAMI CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Specifically, if the shorter wavelength side edge is shifted significantly (up to 37.8nm) to the shorter wavelength as in the case of feature C, there is a problem of changing the hue of the reflected light

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0034] An embodiment of the dielectric multilayer filter 26 shown in FIG. 1 configured as a red-reflecting dichroic filter will now be described. The refractive index values ​​and attenuation coefficients in each embodiment are relative to the design wavelength (reference wavelength) λ in this embodiment 0 .

Embodiment (1

[0036] The dielectric multilayer film 30 was designed with the following parameters.

[0037] Substrate: Glass (refractive index 1.52 and attenuation coefficient 0)

[0038] Middle refractive index material film 34: La 2 o 3 and Al 2 o 3 Composite oxides (refractive index 1.72 and attenuation coefficient 0)

[0039] High refractive index material film 36: Ta 2 o 5 (refractive index 2.19 and attenuation coefficient 0)

[0040] Optical thickness ratio between film 34 and film 36: about 1:2

[0041] Layers: 27

[0042] Reference wavelength (central wavelength of reflection band) λ 0 : 465nm

[0043] Average refractive index of the entire dielectric multilayer film 30: 2.00

[0044] The thickness of each layer in the dielectric multilayer film 30 is shown in Table 1.

[0045] Table 1

[0046] layer number

Material

Optical thickness (nd)

layer number

Material

Optical thickness (nd)

(Substrate)

15

La 2 o 3 +Al 2 o 3...

Embodiment (2

[0061] The dielectric multilayer film 30 was designed with the following parameters.

[0062] Substrate: Glass (refractive index 1.52 and attenuation coefficient 0)

[0063] Middle refractive index material film 34: La 2 o 3 and Al 2 o 3 Composite oxides (refractive index 1.70 and attenuation coefficient 0)

[0064] High refractive index material film 36: Ta 2 o 5 (refractive index 2.16 and attenuation coefficient 0)

[0065] Optical thickness ratio between film 34 and film 36: about 0.5:2 (1:4)

[0066] Layers: 43

[0067] Reference wavelength (central wavelength of reflection band) λ 0 : 533nm

[0068] Average refractive index of the entire dielectric multilayer film 30: 2.04

[0069] The thickness of each layer in the dielectric multilayer film 30 is shown in Table 2.

[0070] Table 2

[0071] layer number

Material

Optical thickness (nd)

layer number

Material

Optical thickness (nd)

(Substrate)

23

La 2 o 3 +Al ...

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Abstract

To provide a dielectric multilayer filter, such as a red-reflective dichroic filter, that has a reduced incident-angle dependency. A dielectric multilayer film 30 is formed on a front surface of a transparent substrate 28 to form a dielectric multilayer filter 26 . The dielectric multilayer film 30 is composed of films 34 of a intermediate-refractive-index material and films 36 of a high-refractive-index material alternately stacked one on another. The intermediate-refractive-index material forming the films 34 has a refractive index higher than 1.52 and equal to or lower than 2.1. The high-refractive-index material forming the films 36 has a refractive index equal to or higher than 2.0 and higher than the refractive index of the intermediate-refractive-index material forming the films 34 . The value of ''the optical thickness of the film 36 of the high-refractive-index material divided by the optical thickness of the film 34 of the intermediate-refractive-index material'' is set to be greater than 1 and equal to or smaller than 4.

Description

technical field [0001] The present invention relates to dielectric multilayer filters with reduced incidence angle dependence. Background technique [0002] Dielectric multilayer filter is an optical filter composed of a group of various thin films made of dielectric materials with different refractive indices, and is used to utilize the interference reflection (removal) of light or transmit specific wavelength components. For example, a dielectric multilayer filter is a so-called IR split filter (infrared split filter) used in CCD cameras to remove infrared light (light with a wavelength greater than about 650nm) that negatively affects color reproduction, and to pass through visible light. piece). Alternatively, the dielectric multilayer filter is a so-called dichroic filter used in liquid crystal projectors to reflect light of a specific color in incident visible light and transmit light of other colors. [0003] Figure 2 shows the structure of an IR split filter using...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B5/20
CPCG02B5/285G02B27/141G02B5/282
Inventor 寺田佳之
Owner MURAKAMI CORP