JP2014235258A - Visible light transmission filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost.SOLUTION: The visible light transmission filter includes: an infrared light cut glass substrate; and an ultraviolet light/infrared light cut film laminating a first material and a second material different in refraction factor on one surface of this infrared light cut glass substrate on any of a plurality of layers of 24 layers to 28 layers alternately in order from the first material high in refraction factor, and is configured to include an antireflection film on the other main surface. The relation between the transmissivity of the ultraviolet light/infrared light cut film only and a wavelength is 5% or more and 50% or less in transmissivity when a wavelength λ is 700 nm, and the transmissivity is 5% or less when the wave length λ is 700 nm to 1200 nm in a state in which the ultraviolet light/infrared light cut film, the infrared light cut glass substrate, and the antireflection film are combined.

Description

  The present invention relates to a visible light transmission filter that transmits visible light.

Conventionally, for example, a digital camera includes a solid-state imaging device, and an optical filter that blocks ultraviolet light and infrared light and transmits visible light is used for color adjustment.
For example, in the case of a digital single-lens reflex camera, a quartz optical low-pass filter (OLPF) in which a quartz birefringent plate for reducing moire and an infrared light cut glass that mainly transmits visible light is used (for example, Patent Documents). 1). This OLPF also serves as a visible light transmission filter that blocks ultraviolet light and infrared light and transmits visible light.
In recent years, the demand for image quality of digital cameras has been on the rise, and the sensitivity to light in the ultraviolet and infrared regions of solid-state imaging devices has been considered a problem, and transparency that largely depends on infrared light cut glass is not sufficient. It has become. In order to solve the problem, 38 to 60 layers of a low-refractive index material and a high-refractive index material are alternately formed on a quartz birefringent plate (see, for example, Patent Document 2), and ultraviolet light and infrared light. An optical thin film filter that blocks visible light and transmits visible light is used together with an infrared light cut filter (see, for example, Patent Document 3).

JP 2006-276313 A Japanese Patent No. 3679268 JP 2005-242052 A

However, a visible light transmission filter in which a low-refractive index material and a high-refractive index material are alternately formed on a quartz crystal birefringent plate as in the past from 38 to 60 layers requires a lot of time for film formation, Further, since there are a large number of films to be stacked, foreign objects are easily caught. Therefore, there is a concern that the manufacturing cost increases in order to prevent foreign matter from being caught while taking a lot of time.
Then, this invention makes it a subject to provide the visible light transmission filter which solves the said subject and reduces manufacturing cost.

  In order to solve the above problems, the present invention provides an infrared light cut glass substrate, and a first material and a second material having different refractive indexes on one surface of the infrared light cut glass substrate, which have a large refractive index. And an ultraviolet light / infrared light cut film laminated alternately in any number of layers from 24 to 28 in order from the first material, and an antireflection film on the other main surface. It is characterized by that.

  In the present invention, the relationship between the transmittance and the wavelength of only the ultraviolet and infrared light cut film is such that the transmittance is 5% or more and 50% or less when the wavelength λ is 700 nm, In a state where the external light cut film, the infrared light cut glass substrate, and the antireflection film are combined, the transmittance is 5% or less when the wavelength λ is 700 nm to 1200 nm.

According to such a visible light transmission filter, even with an ultraviolet / infrared light cut film having a smaller number of layers than the conventional one, the relationship between the transmittance and wavelength equivalent to the conventional one can be obtained.
In addition, although the ultraviolet light infrared light cut film has fewer layers to form than before, variations in the cut of infrared light occur, but an infrared light cut glass is provided on the ultraviolet light infrared light cut film. Thus, the relationship between the transmittance and the wavelength can be made the same as when the conventional ultraviolet and infrared light cut film is provided.
In addition, since the number of layers of the ultraviolet and infrared light cut films is small, the occurrence of foreign object pinching can be reduced, and the production cost can be reduced because the production can be performed in a shorter time than conventional.

It is a perspective view which shows an example of the visible light transmission filter which concerns on embodiment of this invention. It is a conceptual diagram which shows an example of the ultraviolet-light infrared-light cut film of the visible light transmissive filter which concerns on embodiment of this invention. It is a graph which shows an example of the relationship between the transmittance | permeability of an infrared-light cut glass used for the visible light transmission filter which concerns on embodiment of this invention, and a wavelength. It is a graph which shows an example of the transmittance | permeability and wavelength of the ultraviolet light infrared cut film in the case of 24 layers and the case of 38 layers. It is a graph which shows an example of the relationship of the transmittance | permeability and wavelength of the ultraviolet light infrared-light cut film in the case of 26 layers and the case of 38 layers. It is a graph which shows an example of the relationship of the transmittance | permeability and wavelength of the ultraviolet light infrared cut film in the case of 28 layers and the case of 38 layers. It is a graph which shows the relationship between the transmittance | permeability of a visible light transmission filter, and a wavelength in the case where the number of layers of an ultraviolet-light infrared-light cut film is 24 layers, and 38 layers. It is a graph which shows the relationship between the transmittance | permeability of a visible light transmission filter, and a wavelength in the case where the number of layers of an ultraviolet light cut film is 26 layers, and 38 layers. It is a graph which shows the relationship between the transmittance | permeability of a visible light transmission filter, and a wavelength in the case where the number of layers of an ultraviolet-ray infrared-light cut film is 28 layers, and 38 layers.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. Note that each component is exaggerated for easy understanding of the state.

  As shown in FIG. 1, the visible light transmission filter 10 according to the embodiment of the present invention mainly includes an infrared light cut glass substrate 20, an ultraviolet light infrared light cut film 30, and an antireflection film 40. .

As the infrared light cut glass substrate 20 (hereinafter, simply referred to as “substrate”), conventionally known infrared light cut glass is used, and for example, fluorophosphate glass is used.
In addition, the infrared light cut glass substrate 20 is formed with a predetermined thickness, for example, with the light incident surface and the light exit surface being a rectangular flat surface.
This infrared light cut glass substrate 20 plays a role of transmitting light in the visible region and absorbing light in the infrared region. When light in the near infrared region is infrared light, the infrared light is in the wavelength range of 750 nm to 2500 nm. Therefore, the infrared light cut glass substrate 20 can reduce the transmittance of the wavelength λ in which the monochromatic light component is in the range of 750 nm to 2500 nm.

  For example, as shown in FIG. 3, the infrared light cut glass substrate 20 has a maximum transmittance exceeding 90% when the wavelength λ is about 500 nm, and the transmittance is low in the range of about 500 nm to about 750 nm. Thus, the transmittance is about 5% at 700 nm, and the transmittance is less than 5% in the range of about 750 nm to 1100 nm.

This infrared light cut glass substrate 20 is provided with an ultraviolet and infrared light cut film 30 on one main surface and an antireflection film 40 on the other main surface.
Here, one main surface of the infrared light cut glass substrate 20 is a light incident surface, and the other main surface is a light emission surface.

  1 and 2, for example, the optical characteristics of the ultraviolet light / infrared light cut film 30 alone are such that the wavelength λ is 700 nm and the transmittance is 50%, which is higher than 700 nm. When the wavelength is 800 nm, the transmittance is 10% to 55% or less, and when the wavelength λ is 1050 nm to 1200 nm, the transmittance is 40% or less (for example, see FIG. 4).

  The ultraviolet light / infrared light cut film 30 is, for example, a first material having a large refractive index, the first material 31 and the second material 32 having different refractive indexes on one main surface of the infrared light cut glass substrate 20. The layers are alternately stacked in order from 31 to any number from 20 to 29 layers.

For example, TiO ₂ is used as the first material 31 and is used as the first layer on the surface of the infrared light cut glass substrate 20. Thereafter, as the first material 31, TiO ₂ is used in odd numbers.
Next, the second material 32 is made of SiO _{2 and} is used evenly from the second layer thereafter.
TiO ₂ is a material having a higher refractive index than SiO ₂ , and SiO ₂ is a material having a lower refractive index than TiO ₂ .

  For example, when the ultraviolet light / infrared light cut film 30 is composed of 24 layers, the transmittance is 95% or more at a wavelength of about 440 nm to 650 nm, and the visible light is transmitted. Further, the ultraviolet / infrared light cut film 30 has a transmittance of 10% or less at a wavelength of about 900 nm to 1000 nm, and is in a state of cutting infrared light.

  The first material 31 and the second material 32 can be provided on one main surface of the infrared light cut glass substrate 20 by using a conventionally known vapor deposition technique or sputtering technique.

As shown in FIG. 1, the antireflection film 40 is not particularly limited, and a conventionally known antireflection film can be used.
For example, when a base layer is provided on the other main surface of the infrared light cut glass substrate 20, the antireflection film 40 can be formed by alternately forming a TiO ₂ layer and SiO ₂ in order from the surface of the base layer. .

Alternatively, Al ₂ O ₃ , ZrO ₂ , and MgF ₂ can be formed in order from the surface of the underlayer. In addition, you may produce an antireflection film other than an above-described vapor deposition material and structure.

  The visible light transmission filter 10 according to the embodiment of the present invention cannot cut infrared light sufficiently with the transmittance of the ultraviolet light / infrared light cut film 30 alone. Even the external light cut film 30 is affected by the transmittance of the infrared light cut glass substrate 20, and therefore the transmittance can be 5% or less in the wavelength range of 750 nm to 1200 nm. That is, visible light can be transmitted and ultraviolet light and infrared light can be cut.

In addition, since the visible light transmission filter according to the embodiment of the present invention is configured as described above, even if it is an ultraviolet ray infrared light cut film having a smaller number of layers than the conventional one, visible light transmission equivalent to the conventional one is possible. Rate and infrared light transmittance.
In addition, although the ultraviolet light infrared light cut film has inferior optical characteristics because the number of layers to be formed is smaller than that of the conventional film, the ultraviolet light infrared light cut film is provided on the infrared light cut glass. Optical characteristics equivalent to the case of providing an ultraviolet light / infrared light cut film can be obtained.
In addition, since the number of layers to be formed is smaller than the conventional number, the manufacturing cost can be reduced.

Next, examples of the present invention will be described.
As shown in Table 1, the case where the design wavelength is 1000 nm and the number of layers of the ultraviolet light cut film is 24 is referred to as Example 1, the case of 26 layers is referred to as Example 2, and the case of 28 layers is performed. Example 3 is used, and the case of 38 layers is referred to as Comparative Example 1.
In this case, both, the first layer of the substrate side TiO ₂ (in the table "TIO2") is used as the first material 31, a second layer is SiO ₂ (in Table as the second material 32 ' SIO2 ") is used.

(Comparative Example 1)
First, a comparative example will be described.
Comparative Example 1 has a configuration in which an ultraviolet light infrared cut film comprising 38 layers is provided on one main surface of an infrared light cut glass as shown in FIG. 3, and an antireflection film is provided on the other main surface. Visible light transmission filter, which can be used as a normal optical device.
In Comparative Example 1, as shown in Table 1, the ultraviolet light / infrared light cut film has a predetermined physical thickness (nm) and optical thickness (nm) for each layer.
As shown in FIG. 4, the visible light transmission filter having the ultraviolet light / infrared light cut film thus formed has a steep slope with a transmittance close to 100% within a wavelength range of 400 nm to 450 nm, and 650 nm to 700 nm. Within a range below, the transmittance changes steeply toward 0%. From the graph showing the relationship between the wavelength and the transmittance (see FIG. 4), the 38-layer ultraviolet / infrared light cut film of Comparative Example 1 has a visible light of 95% or more in the wavelength range of 440 nm to less than 650 nm. It is confirmed that the transmittance is 5% or less at 700 nm and the infrared light is cut in a range from a value higher than 700 nm to 1150 nm with a transmittance of 10% or less.

  In Comparative Example 1, as shown in FIG. 7, the wavelength is in the range of 440 nm to 550 nm with 38 layers of the ultraviolet light infrared light cut film and the antireflection film provided on the infrared light cut glass. The transmittance is 90% or more, and it can be confirmed that visible light is transmitted. In addition, in the wavelength range of 700 nm to 1200 nm, the transmittance is 5% or less, and it can be confirmed that the infrared light is cut off.

Example 1
Example 1 is configured such that an infrared light cut film comprising 24 layers is provided on one main surface of an infrared light cut glass as shown in Table 1, and an antireflection film is provided on the other main surface. It is a visible light transmission filter.
In Example 1, as shown in Table 1, the ultraviolet light / infrared light cut film has a predetermined physical thickness (nm) and optical thickness (nm) for each layer.
As shown in FIG. 4, the visible light transmission filter having the ultraviolet light / infrared light cut film thus formed has a steep slope with a transmittance close to 100% in a wavelength range of 400 nm to 450 nm, and is about 600 nm to In the range of 850 nm, the transmittance changes with a gradient that approaches 0%. From the graph showing the relationship between the wavelength and the transmittance (see FIG. 4), the 24-layer ultraviolet / infrared light cut film of Example 1 has a visible light of 95% or more in the wavelength range of 440 nm to about 600 nm. It can be confirmed that the transmittance is 50% at a wavelength of 700 nm, the transmittance is 10% or less in the range of 850 to 1000 nm, and infrared light is cut off.

In Example 1, as shown in FIG. 7, in a state where the wavelength is in the range of 440 nm to 550 nm with the infrared light cut glass provided with 24 layers of the ultraviolet light infrared light cut film and the antireflection film. The transmittance is 90% or more, and it can be confirmed that visible light is transmitted. In addition, in the wavelength range of 700 nm to 1200 nm, the transmittance is 5% or less, and it can be confirmed that the infrared light is cut off.
That is, although the transmittance value at around 700 nm is high, the transmittance is the same as that of Comparative Example 1. Thereby, the visible light transmission filter of Example 1 can be used as a normal optical device.

(Example 2)
Example 2 is configured such that an infrared light cut film composed of 26 layers is provided on one main surface of an infrared light cut glass as shown in Table 1, and an antireflection film is provided on the other main surface. It is a visible light transmission filter.
In Example 2, as shown in Table 1, the ultraviolet and infrared light cut film has a predetermined physical thickness (nm) and optical thickness (nm) for each layer.
As shown in FIG. 5, the visible light transmission filter in which the ultraviolet light and infrared light cut film is configured in this manner has a steep slope with a transmittance close to 100% in a wavelength range of 400 nm to 450 nm, and is about 650 nm to In the range of 750 nm, the transmittance changes steeply approaching 0%. From the graph showing the relationship between the wavelength and the transmittance (see FIG. 5), the 26-layer ultraviolet / infrared light cut film of Example 2 has a visible light of 95% or more in the wavelength range of 440 nm to about 650 nm. It can be confirmed that the transmittance is 15% or less at a wavelength of 700 nm and the transmittance after 750 nm is irregular.

As shown in FIG. 8, Example 2 has a wavelength in the range of 440 nm to 550 nm with 26 layers of ultraviolet light infrared light cut film and antireflection film provided on the infrared light cut glass. The transmittance is 90% or more, and it can be confirmed that visible light is transmitted. In addition, in the wavelength range of 700 nm to 1200 nm, the transmittance is 5% or less, and it can be confirmed that the infrared light is cut off.
That is, although the transmittance value at around 700 nm is high, the transmittance is the same as that of Comparative Example 1. Thereby, the visible light transmission filter of Example 2 can be used as a normal optical device.

Example 3
Example 3 has a configuration in which an ultraviolet light infrared light cut film composed of 28 layers is provided on one main surface of an infrared light cut glass as shown in Table 1, and an antireflection film is provided on the other main surface. It is a visible light transmission filter.
In Example 3, as shown in Table 1, the ultraviolet light / infrared light cut film has a predetermined physical thickness (nm) and optical thickness (nm) for each layer.
As shown in FIG. 6, the visible light transmission filter in which the ultraviolet light and infrared light cut film is configured as described above has a steep slope with a transmittance close to 100% in a wavelength range of 400 nm to 450 nm. In the range of 750 nm, the transmittance changes steeply approaching 0%. From the graph showing the relationship between the wavelength and the transmittance (see FIG. 6), the 28-layer ultraviolet / infrared light cut film of Example 3 has 95% or more visible light in the wavelength range of 440 nm to about 650 nm. It can be confirmed that the transmittance is 10% or less at a wavelength of 700 nm and the transmittance after 750 nm is irregular.

As shown in FIG. 9, Example 3 has a wavelength in the range of 440 nm to 550 nm with 28 layers of ultraviolet light infrared light cut film and antireflection film provided on the infrared light cut glass. The transmittance is 90% or more, and it can be confirmed that visible light is transmitted. In addition, in the wavelength range of 700 nm to 1200 nm, the transmittance is 5% or less, and it can be confirmed that the infrared light is cut off.
That is, the transmittance is the same as that of Comparative Example 1. Thereby, the visible light transmission filter of Example 3 can be used as a normal optical device.

10 UV light infrared light cut filter 20 Infrared light cut glass substrate 30 UV light infrared light cut film 31 First material 32 Second material 40 Antireflection film

Claims (2)

An infrared light cut glass substrate;
The first material and the second material having different refractive indexes on one surface of the infrared light cut glass substrate are alternately arranged in any order from the first material having the higher refractive index to the 24th layer to the 28th layer. With ultraviolet and infrared light cut films stacked in number,
A visible light transmission filter comprising an antireflection film on the other main surface. When the wavelength λ is 700 nm, the transmittance is 5% or more and 50% or less when the wavelength λ is 700 nm.
In a state where the ultraviolet light infrared light cut film, the infrared light cut glass substrate and the antireflection film are combined,
The visible light transmission filter according to claim 1, wherein the transmittance is 5% or less when the wavelength λ is 700 nm to 1200 nm.

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