Optical filter

Abstract

To provide an optical filter inhibiting ripple and stray light in a visible light region and excellent in transmissivity in the visible light region and shielding property in a near infrared light region.SOLUTION: The optical filter includes in this order: a first dielectric multilayer film; a resin film; a phosphate glass containing 40% or more of P2O5 in oxide-based mass percentage indication; and a second dielectric multilayer film. The resin film includes resin and near-infrared absorption dye. The second dielectric multilayer film includes an H2 layer with refractive index and QWOT in a specific range. When the H2 layer closest to the phosphate glass is defined as a first H2 layer, a first M2 layer, QWOT of which satisfies a specific range is included between the first H2 layer and the phosphate glass. The optical filter satisfies all of prescribed spectral characteristics (i-1) to (i-2).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical filter that transmits visible light and blocks near-infrared light. [Background technology]

[0002] In order to reproduce color tones well and obtain clear images, imaging devices using solid-state imaging elements use optical filters that transmit light in the visible range (hereinafter also referred to as "visible light") and block light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light").

[0003] Such optical filters can be made in various types, for example, a reflective filter in which dielectric thin films with different refractive indices are alternately stacked on one or both sides of a transparent substrate (dielectric multilayer film) and the optical interference is utilized to reflect light to be blocked.

[0004] Patent Documents 1 and 2 describe optical filters having a dielectric multilayer film and an absorption layer containing a dye. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2014 / 002864 [Patent Document 2] International Publication No. 2018 / 043564 Summary of the Invention [Problem to be solved by the invention]

[0006] Optical filters having a dielectric multilayer film have a problem in that the optical thickness of the dielectric multilayer film changes depending on the angle of incidence of light, and therefore the spectral transmittance curve and the spectral reflectance curve change depending on the angle of incidence. For example, depending on the number of layers of the multilayer film, interference caused by reflected light at the interface of each layer causes a drastic change in the transmittance in the visible light region, a so-called ripple, and the larger the angle of incidence of light, the stronger the change tends to occur. This causes a problem in that the amount of light taken in the visible light region changes at high angles of incidence, resulting in a decrease in image reproducibility. In particular, with the recent trend toward lowering the height of camera modules, it is expected that they will be used under high angle of incidence conditions, and therefore optical filters that are less susceptible to the effects of the angle of incidence are required.

[0007] In addition, in conventional optical filters that utilize the reflection of a dielectric multilayer film, the reflected light may be reflected again by the lens surface and enter the filter, or the light reflected by the sensor surface may be reflected again by the dielectric multilayer film surface and enter the filter, resulting in the phenomenon of light being emitted outside the originally intended optical path, i.e., so-called stray light. The use of such filters may cause flare or ghosting in the solid-state imaging element, or may result in degradation of image quality. In particular, with the recent trend toward higher image quality in camera modules, there is a demand for optical filters that are less susceptible to stray light.

[0008] An object of the present invention is to provide an optical filter in which ripples and stray light in the visible light region are suppressed and which has excellent transmittance in the visible light region and excellent shielding properties in the near-infrared light region. [Means for solving the problem]

[0009] The present invention provides an optical filter having the following configuration. [1] An optical filter comprising, in this order, a first dielectric multilayer film, a resin film, phosphate glass, and a second dielectric multilayer film, the resin film contains a resin and a near-infrared absorbing dye, The phosphate glass contains 40% or more P2O5 in terms of mass percentage based on oxides, the first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers having different refractive indices; The second dielectric multilayer film includes at least one H2 layer having a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less; When the layer closest to the phosphate glass among the H2 layers is defined as a first H2 layer, a first M2 layer between the first H2 layer and the phosphate glass, the first M2 layer being a single layer having a QWOT of 1.2 to 1.8 or a plurality of layers having a total QWOT of 1.2 to 1.8; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-2): (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 450-550(0deg)AVE More than 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 450-550(50deg)AVE More than 85% [2] An optical filter comprising a first dielectric multilayer film, a resin film, phosphate glass, and a second dielectric multilayer film in this order, the resin film contains a resin and a near-infrared absorbing dye, The phosphate glass contains 40% or more P2O5 in terms of mass percentage based on oxides, the first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers having different refractive indices; the first dielectric multilayer film includes at least one H1 layer having a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less; When the layer closest to the resin film among the H1 layers is defined as a first H1 layer, a first M1 layer between the first H1 layer and the resin film, the first M1 layer being a single layer having a QWOT of 1.2 or more and 1.8 or a plurality of layers having a total QWOT of 1.2 or more and 1.8 or less; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-2): (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 450-550(0deg)AVE More than 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 450-550(50deg)AVE More than 85% Effect of the Invention

[0010] According to the present invention, it is possible to provide an optical filter that suppresses ripples and stray light in the visible light region and has excellent transmittance in the visible light region and excellent shielding properties in the near-infrared light region. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view that illustrates an example of an optical filter according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional schematic diagram showing the configuration of the optical filter of Example 2-1. [Diagram 3] FIG. 3 is a cross-sectional schematic diagram showing the configuration of the optical filter of Example 2-2. [Figure 4] FIG. 4 is a cross-sectional view illustrating the configuration of the optical filter of Example 2-3. [Diagram 5] FIG. 5 is a diagram showing the spectral transmittance curve of glass. [Figure 6] FIG. 6 is a diagram showing the spectral transmittance curve of the optical filter of Example 2-1. [Figure 7] FIG. 7 is a diagram showing the spectral reflectance curve of the optical filter of Example 2-1. [Figure 8] FIG. 8 is a diagram showing the spectral transmittance curve of the optical filter of Example 2-4. [Figure 9] FIG. 9 is a diagram showing the spectral reflectance curve of the optical filter of Example 2-4. [Figure 10] FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter of Example 2-5. [Figure 11] FIG. 11 is a diagram showing the spectral reflectance curve of the optical filter of Example 2-5. [Figure 12] FIG. 12 is a diagram showing the spectral transmittance curve of the optical filter of Example 2-6. [Figure 13] FIG. 13 is a diagram showing the spectral reflectance curve of the optical filter of Example 2-6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described. In this specification, the near-infrared absorbing dye may be abbreviated as "NIR dye" and the ultraviolet absorbing dye may be abbreviated as "UV dye". In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. The dye made of compound (I) is also referred to as dye (I), and the same applies to other dyes.

[0013] In this specification, the internal transmittance is the transmittance obtained by subtracting the effect of interface reflection from the measured transmittance, as expressed by the formula {measured transmittance (incident angle 0 degrees) / (100-reflectance (incident angle 5 degrees))}×100. In this specification, the transmittance of a substrate and the transmittance of a resin film including a case where a dye is contained in the resin are all "internal transmittance" even when they are described as "transmittance". On the other hand, the transmittance measured by dissolving a dye in a solvent such as dichloromethane, the transmittance of a dielectric multilayer film, and the transmittance of an optical filter having a dielectric multilayer film are actually measured transmittances.

[0014] In this specification, for example, a transmittance of 90% or more in a specific wavelength range means that the transmittance is not below 90% in the entire wavelength range, i.e., the minimum transmittance is 90% or more in the wavelength range. Similarly, for example, a transmittance of 1% or less in a specific wavelength range means that the transmittance is not more than 1% in the entire wavelength range, i.e., the maximum transmittance is 1% or less in the wavelength range. The same applies to internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic mean of the transmittance and internal transmittance per 1 nm in the wavelength range. The spectral characteristics can be measured using a UV-Vis spectrophotometer. In this specification, the term "to" indicating a numerical range includes the upper and lower limits.

[0015] <Optical filters> 1 is a cross-sectional view showing an optical filter (hereinafter also referred to as "the present filter") according to one embodiment of the present filter. The present filter 1B includes, in this order, a first dielectric multilayer film 20B, a resin film 12, phosphate glass 11, and a second dielectric multilayer film 20A. Here, the resin film contains a resin and a dye having a maximum absorption wavelength in the resin at 690 to 800 nm.

[0016] In the present invention, at least one of the first and second dielectric multilayer films has low reflectance even at a high angle of incidence, as described below, and thus stray light is suppressed. In addition, the light blocking properties of the optical filter are substantially guaranteed by the absorption properties of the phosphate glass. Since the absorption properties are not affected by the angle of incidence of light, the optical filter as a whole can achieve excellent transmittance in the visible light region and excellent blocking properties in the near-infrared light region while suppressing ripples in the visible light region.

[0017] <Optical filter characteristics> The optical filter of the present invention satisfies all of the following spectral characteristics (i-1) to (i-4). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 450-550(0deg)AVE More than 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 450-550(50deg)AVE More than 85% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE is 2.5% or less (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE is 2.5% or less

[0018] This filter, which satisfies all of the spectral characteristics (i-1) to (i-4), has high transmittance in the visible light region as shown in characteristic (i-1), and high blocking performance in the near-infrared region as shown in characteristic (i-3). Furthermore, as shown in characteristics (i-2) and (i-4), the change in the spectral characteristics at high angles of incidence is small, and ripples in the visible light region are suppressed.

[0019] Satisfying the spectral characteristics (i-1) and (i-2) means that the transmittance of the visible light region of 450 to 550 nm is excellent even at a high angle of incidence. Average transmittance T 450-550(0deg)AVE is preferably 88% or more, more preferably 91% or more. Average transmittance T 450-550(50deg)AVE is preferably 87% or more, more preferably 89% or more.

[0020] Satisfying the spectral characteristics (i-3) and (i-4) means that the transmittance of the near-infrared light region of 750 to 1000 nm is excellent even at a high angle of incidence. Average transmittance T 750-1000(0deg)AVE is preferably 1.5% or less, more preferably 1% or less. Average transmittance T 750-1000(50deg)AVE is preferably 1% or less, more preferably 0.5% or less.

[0021] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristics (i-5) to (i-8). (i-5) When the incident direction is the second dielectric multilayer film side, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-6) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-7) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-8) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5%

[0022] The spectral characteristics (i-5) and (i-6) define the reflection characteristics on the second dielectric multilayer film side, and the spectral characteristics (i-7) and (i-8) define the reflection characteristics on the second dielectric multilayer film side at high angles of incidence. Since the reflectance in the visible light and near-infrared light regions is small even at high angles of incidence, reflection on the surface of the second dielectric multilayer film, which is a cause of stray light, can be suppressed. Average reflectance R2 750-1000(5deg)AVE is more preferably 1.5% or less, and further preferably 1% or less. Average reflectance R2 450-600(5deg)AVE is more preferably 1.5% or less, and further preferably 1% or less. Average reflectance R2 750-1000(50deg)AVE is more preferably 3% or less, and further preferably 2% or less. Average reflectance R2 450-600(50deg)AVE is more preferably 4% or less, and further preferably 3% or less.

[0023] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristics (i-9) to (i-12). (i-9) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 1000-1200(0deg)AVE Less than 7% (i-10) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 1000-1200(50deg)AVE Less than 7% (i-11) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 at which the transmittance is 30% (0deg) But the wavelength is 630~680nm. (i-12) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 at which the transmittance is 30% (50deg) But the wavelength is 630~680nm.

[0024] Satisfying the spectral characteristics (i-9) and (i-10) means that the film has excellent light-shielding properties in the near-infrared region of 1000 to 1200 nm even at a high angle of incidence. Average transmittance T 1000-1200(0deg)AVE is more preferably 5% or less, and further preferably 3% or less. Average transmittance T 1000-1200(50deg)AVE is more preferably 3% or less, and further preferably 2% or less.

[0025] Satisfying the spectral characteristics (i-11) and (i-12) means that light in the near-infrared region can be blocked even at a high angle of incidence, and visible transmitted light can be efficiently captured. Wavelength IR30 (0deg) It is more preferably in the range of 640 to 675 nm, and even more preferably in the range of 640 to 670 nm. Wavelength IR30 (50deg) It is more preferably in the range of 640 to 675 nm, and even more preferably in the range of 640 to 670 nm.

[0026] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristics (i-13) to (i-16). (i-13) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-14) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-16) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5%

[0027] The spectral characteristics (i-13) and (i-14) define the reflection characteristics on the first dielectric multilayer film side, and the spectral characteristics (i-15) and (i-16) define the reflection characteristics on the first dielectric multilayer film side at high angles of incidence. Since the reflectance is small even at a high angle of incidence, reflection on the dielectric multilayer film surface, which is a cause of stray light, can be suppressed. Average reflectance R1 750-1000(5deg)AVE is more preferably 1.5% or less, and further preferably 1% or less. Average reflectance R1 450-600(5deg)AVE is more preferably 1.5% or less, and further preferably 1% or less. Average reflectance R1 750-1000(50deg)AVE is more preferably 3.5% or less, and further preferably 2% or less. Average reflectance R1 450-600(50deg)AVE is more preferably 4% or less, and further preferably 3.5% or less.

[0028] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristics (i-17) to (i-20). (i-17) Average transmittance T 450-550(0deg)AVE and the average transmittance T 450-550(50deg)AVE The absolute value of the difference is 3.5% or less (i-18) Average transmittance T 750-1000(0deg)AVE and the average transmittance T 750-1000(50deg)AVE The absolute value of the difference is 1.5% or less (i-19) Average transmittance T 1000-1200(0deg)AVE and the average transmittance T 1000-1200(50deg)AVE The absolute value of the difference is 1.5% or less (i-20) Wavelength IR30 (0deg) and wavelength IR30 (50deg) The absolute value of the difference is 15 nm or less

[0029] Satisfying the spectral characteristics (i-17) to (i-19) means that the transmittance in the visible light region of 450 to 600 nm and the near-infrared light region of 750 to 1200 nm is less likely to change even at high angles of incidence, that is, ripples are suppressed. The absolute value of the spectral characteristic (i-17) is more preferably 3.2% or less, and further preferably 3% or less. The absolute value of the spectral characteristic (i-18) is more preferably 1% or less, and further preferably 0.5% or less. The absolute value of the spectral characteristic (i-19) is more preferably 1.3% or less, and further preferably 1.2% or less.

[0030] Satisfying the spectral characteristic (i-20) means that the spectral transmittance curve in the 630 to 680 nm region is less likely to shift even at a high angle of incidence. The absolute value of the spectral characteristic (i-20) is more preferably 10 nm or less, and further preferably 8 nm or less.

[0031] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristic (i-21). (i-21) When the second dielectric multilayer film side is the incident direction, the average absorption loss amount defined below is 95% or more in the wavelength range of 750 to 1000 nm. (Absorption loss) [%] = 100 - (Transmittance at an incidence angle of 5 degrees) - (Reflectance at an incidence angle of 5 degrees)

[0032] Satisfying the spectral characteristic (i-21) means that both the transmittance in the visible light region and the blocking property in the near-infrared light region are achieved. The average absorption loss is more preferably 96% or more, and further preferably 97% or more.

[0033] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristic (i-22). (i-22) When the second dielectric multilayer film side is the incident direction, the minimum absorption loss is 90% or more in the wavelength range of 750 to 1000 nm.

[0034] Satisfying the spectral characteristic (i-22) means that the transparency in the visible light region and the blocking property in the near-infrared light region are compatible. The minimum absorption loss is more preferably 92% or more, and further preferably 94% or more.

[0035] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristic (i-23). (i-23) When the second dielectric multilayer film side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the reflectance R2 for each wavelength is 1 nm intervals from 750 nm to 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R2 n(5deg)However, there are more than 200 n values ​​for which the probability is less than 1%.

[0036] The spectral characteristic (i-23) defines the reflection characteristic on the second dielectric multilayer film side, and a small reflectance means that reflection on the dielectric multilayer film surface, which causes stray light, can be suppressed. Reflectance R2 n(5deg) is 1% or less, is more preferably 220 or more, and further preferably 230 or more.

[0037] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristic (i-24). (i-24) When the first dielectric multilayer film side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the reflectance R1 for each wavelength is 1 nm intervals from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R1 n(5deg) However, there are more than 150 n values ​​for which the probability is less than 1%.

[0038] The spectral characteristic (i-24) defines the reflection characteristic on the first dielectric multilayer film side, and a small reflectance means that reflection on the dielectric multilayer film surface, which causes stray light, can be suppressed. Reflectance R1 n(5deg) is 1% or less, is more preferably 180 or more, and further preferably 200 or more.

[0039] It is preferable that the optical filter of the present invention further satisfies the following spectral characteristics (i-25) to (i-28). (i-25) The minimum transmittance T at wavelengths of 450 to 550 nm in the spectral transmittance curve at an incident angle of 0 degrees 450-550(0deg)MIN More than 83% (i-26) In the spectral transmittance curve at an incident angle of 0 degrees, the maximum transmittance T 450-550(0deg)MAX More than 90% (i-27) In the spectral transmittance curve at an incident angle of 0 degrees, the maximum transmittance T 750-1000(0deg)MAX is 1.2% or less (i-28) In the spectral transmittance curve at an incident angle of 0 degrees, the maximum transmittance T 1000-1200(0deg)MAX Less than 7%

[0040] Satisfying characteristics (i-25) and (i-26) means that the material has excellent visible light transmittance, and satisfying characteristics (i-27) and (i-28) means that the material has excellent near-infrared shielding properties.

[0041] Minimum transmittance T 450-550(0deg)MIN is more preferably 85% or more, and further preferably 87% or more. Maximum transmittance T 450-550(0deg)MAX is more preferably 92% or more, and further preferably 94% or more. Maximum transmittance T 750-1000(0deg)MAX is more preferably 1% or less, and further preferably 0.9% or less. Maximum transmittance T 1000-1200(0deg)MAX is more preferably 5% or less, and further preferably 4% or less.

[0042] <Second dielectric multilayer film> In this filter, it is preferable that the second dielectric multilayer film suppresses reflection in the visible light region and the near-infrared light region even at a high incidence angle. In the present invention, since the second dielectric multilayer film suppresses reflection in the visible light region and the near-infrared light region, an optical filter is obtained in which the generation of ripples in the visible light region is reduced and the spectral characteristics are less likely to change with respect to light at a high incidence angle, thereby suppressing stray light.

[0043] The second dielectric multilayer film is a multilayer film including a plurality of layers having different refractive indices, and these layers are alternately laminated. More specifically, the second dielectric multilayer film includes a low refractive index dielectric layer (low refractive index layer), a medium refractive index dielectric layer (medium refractive index layer), and a high refractive index dielectric layer (high refractive index layer), and is a multilayer film in which two or more of these dielectric layers are alternately laminated.

[0044] The high refractive index layer preferably has a refractive index of 1.6 or more at a wavelength of 500 nm, more preferably 2.2 to 2.5. Examples of materials for the high refractive index layer include Ta2O5, TiO2, TiO, Ti2O3, and Nb2O5. Other commercially available products include OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), and OA600 (a mixture of Ta2O5 and TiO2), all manufactured by Canon Optron. Among these, TiO2 is preferred from the standpoint of film-forming properties, reproducibility in refractive index, and stability.

[0045] The medium refractive index layer preferably has a refractive index of 1.6 or more and less than 2.2 at a wavelength of 500 nm. Examples of materials for the medium refractive index layer include ZrO2, Nb2O5, Al2O3, HfO2, OM-4, OM-6 (a mixture of Al2O3 and ZrO2), and OA-100 sold by Canon Optron, and H4 and M2 (alumina lanthania) sold by Merck. Among these, Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred from the standpoint of film-forming properties, reproducibility in refractive index, and stability.

[0046] The low refractive index layer preferably has a refractive index of less than 1.6 at a wavelength of 500 nm, more preferably 1.38 to 1.5. Examples of the material for the low refractive index layer include SiO2, SiO x N y、 Examples of commercially available products include S4F and S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Co., Ltd. Among these, SiO2 is preferred from the standpoint of reproducibility, stability, and economy in film formation.

[0047] (Structure of the second dielectric multilayer film) 2 is a schematic cross-sectional view showing the configuration of an optical filter produced in Example 2-1 described later. In Example 2-1, the second dielectric multilayer film 20A has a laminated structure in which TiO2 (refractive index at 500 nm: 2.467) is alternately laminated as a high refractive index layer and SiO2 (refractive index at 500 nm: 1.483) is alternately laminated as a low refractive index layer. However, this embodiment is not limited to this configuration, and the above materials can be selected arbitrarily.

[0048] The second dielectric multilayer film includes at least one H2 layer having a refractive index at 500 nm of 1.8 to 2.5 and a QWOT (Quarter Wave Optical Thickness) of 1.1 to 3.5, as shown in Fig. 2. The refractive index of the H2 layer is preferably 1.9 to 2.5, more preferably 2.0 to 2.5, and even more preferably 2.1 to 2.5.

[0049] Here, the QWOT is calculated by the following formula: QWOT = (physical thickness / center wavelength) x 4 x refractive index The unit of physical film thickness is [nm], the central wavelength is 500 nm, and the refractive index is the refractive index at a wavelength of 500 nm.

[0050] As shown in FIG. 2, when the H2 layer closest to the phosphate glass is defined as the first H2 layer, the second dielectric multilayer film includes a first M2 layer between the first H2 layer and the phosphate glass, the first M2 layer being made up of multiple continuous layers, with the sum of the QWOT of each layer satisfying a range of 1.2 to 1.8. In the example shown in Fig. 2, the first M2 layer is composed of four layers, from the first layer to the fourth layer, with the layer closest to the phosphate glass being the first layer, but the first M2 layer may be composed of any number of layers as long as the sum of the QWOT of each layer is 1.2 to 1.8. That is, the first M2 layer may be a single layer that satisfies the QWOT of 1.2 to 1.8. However, from the viewpoint of improving productivity, the first M2 layer is preferably composed of 6 layers or less, and more preferably 3 layers or less.

[0051] The inventors have found that when the second dielectric multilayer film has the above-mentioned configuration, the first M2 layer functions as an intermediate refractive index layer, smoothing the spectral waveform, thereby suppressing reflection over a wide wavelength range from the visible light region to the near-infrared light region, and further suppressing the incidence angle dependence of the reflection characteristics, thereby suppressing stray light.

[0052] More specifically, the second dielectric multilayer film has the above-mentioned configuration, and thus the following characteristics are obtained. (i-5) When the incident direction is the second dielectric multilayer film side, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-6) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-7) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-8) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5%

[0053] In this embodiment, the first M2 layer may be disposed at any position between the first H2 layer and the phosphate glass. Specifically, in Fig. 2, the first M2 layer is composed of all layers (first to fourth layers) between the phosphate glass and the first H2 layer, but the layer (first layer) closest to the phosphate glass to the third layer (third layer) may be the first M2 layer (in this case, the sum of the QWOTs of the first to third layers is 1.423), and the SiO2 layer (fourth layer) closest to the first H2 layer may be an arbitrary layer.

[0054] In addition, when there is a single layer having a QWOT of 1.2 or more and 1.8 or multiple consecutive layers having a total QWOT of 1.2 or more and 1.8 or less between the first H2 layer and the phosphate glass, any one of the single layer or multiple consecutive layers is defined as the first M2 layer, and the other layers are defined as any layer.

[0055] As described above, in this embodiment, as long as the first M2 layer is included between the first H2 layer and the phosphate glass, an arbitrary layer may be included between the first H2 layer and the phosphate glass as long as the effect of the present invention is not hindered. The arbitrary layer may be included, for example, between the phosphate glass and the first M2 layer, or between the first M2 layer and the first H2 layer. However, from the viewpoint of suppressing reflection, it is most preferable that no arbitrary layer is present between the first H2 layer and the phosphate glass. In other words, it is preferable that the first H2 layer, the first M2 layer, and the phosphate glass are continuously formed.

[0056] Materials for the optional layers include the high refractive index layers, the medium refractive index layers, and the low refractive index layers described above.

[0057] Furthermore, the second dielectric multilayer film may be configured to include two or more H2 layers as shown in Fig. 3. In this case, as shown in Fig. 3, when the layer second closest to the phosphate glass is the second H2 layer, it is preferable to include a second M2 layer between the first H2 layer and the second H2 layer, the second M2 layer being made up of multiple continuous layers whose sum of the QWOTs of the layers is 1.2 to 2.1. By including the second M2 layer between the first H2 layer and the second H2 layer, the second M2 layer functions as an intermediate refractive index layer, making the spectral waveform smoother, and thus further suppressing reflection in a wide wavelength range from the visible light region to the near infrared light region.

[0058] In the example shown in Fig. 3, the second M2 layer is composed of three layers, from the sixth layer to the eighth layer, but the second M2 layer may be composed of any number of layers as long as the sum of the QWOT of each layer is 1.2 to 2.1. That is, the second M2 layer may be a single layer that satisfies the QWOT of 1.2 to 2.1. However, from the viewpoint of improving productivity, the second M2 layer is preferably composed of six layers or less, and more preferably three layers or less.

[0059] Furthermore, in this embodiment, as shown in Fig. 4, it is preferable to include two single layers having a QWOT of 1.2 to 2.1 or two consecutive layers having a total QWOT of 1.2 to 2.1 between the first H2 layer and the second H2 layer. At this time, as shown in Fig. 4, the layer closest to the second H2 layer among the corresponding single layers or consecutive layers is the second M2 layer, and the layer second closest to the second H2 layer is the third M2 layer. That is, it is preferable that the second dielectric multilayer film includes, in addition to the second M2 layer, a third M2 layer consisting of a single layer having a QWOT of 1.2 to 2.1 or a plurality of layers having a total QWOT of 1.2 to 2.1 between the first H2 layer and the second M2 layer.

[0060] When the second dielectric multilayer film has this configuration, the third M2 layer functions as an intermediate refractive index layer, smoothing the spectral waveform, thereby further suppressing reflection over a wide wavelength range from the visible light region to the near-infrared light region.

[0061] The second M2 layer and the third M2 layer may be disposed at any position, so long as the layer closest to the second H2 layer is the second M2 layer, as described above.

[0062] In the example shown in Figure 4, there are two single layers (the second M2 layer and the third M2 layer) between the first H2 layer and the second H2 layer that have a QWOT of 1.2 to 2.1 or two consecutive layers whose total QWOT is 1.2 to 2.1, but there may be three or more such single layers or consecutive layers.

[0063] In addition, between the first H2 layer and the second H2 layer, an optional layer may be included in addition to the second M2 layer and the third M2 layer, as long as the effect of the present invention is not hindered. The optional layer may be the same as that described above. However, from the viewpoint of improving productivity, it is preferable that no optional layer is present. That is, it is most preferable that the second H2 layer, the second M2 layer, the third M2 layer, and the first H2 layer are formed continuously. Even if there is no third M2 layer, it is preferable that no optional layer is present, and the second H2 layer, the second M2 layer and the first H2 layer are formed continuously.

[0064] From the viewpoint of further suppressing reflection, it is preferable that the QWOT of the first H2 layer and the second H2 layer in the second dielectric multilayer film are different from each other. From the same viewpoint, it is preferable that the QWOT of the single layer constituting the first M2 layer, the second M2 layer and the third M2 layer or the total value of the QWOT of multiple consecutive layers are different from each other.

[0065] The total number of laminated dielectric layers in the second dielectric multilayer film is preferably 10 to 30, and more preferably 10 to 20. When the total number of laminated layers is within the above range, an increase in the film thickness per layer can be prevented.

[0066] The total thickness of the second dielectric multilayer film is preferably 0.5 to 2.0 μm, more preferably 0.5 to 1.0 μm. When the thickness of the second dielectric multilayer film is within the above range, an increase in the thickness per layer can be prevented.

[0067] The second dielectric multilayer film and the first dielectric multilayer film described below can be formed by, for example, a vacuum film formation process such as a CVD method, a sputtering method, or a vacuum deposition method, or a wet film formation process such as a spray method or a dipping method.

[0068] <First dielectric multilayer film> In the present filter, the first dielectric multilayer film preferably suppresses reflection in the visible light region and the near-infrared light region. By suppressing reflection in the visible light region and the near-infrared light region with the first dielectric multilayer film, the generation of ripples in the visible light region is reduced, and further, the spectral characteristics are less likely to change with respect to light with a high angle of incidence, thereby obtaining an optical filter in which stray light is suppressed.

[0069] The first dielectric multilayer film is a multilayer film including a plurality of layers having different refractive indices, and these layers are alternately laminated. More specifically, the first dielectric multilayer film includes a low refractive index dielectric layer (low refractive index layer), a medium refractive index dielectric layer (medium refractive index layer), and a high refractive index dielectric layer (high refractive index layer), and is a multilayer film in which two or more of these dielectric layers are alternately laminated.

[0070] The refractive indices and materials of the high refractive index layer, the medium refractive index layer and the low refractive index layer may be similar to those of the second dielectric multilayer film.

[0071] (Structure of the first dielectric multilayer film) In this embodiment, the first dielectric multilayer film includes at least one H1 layer having a refractive index of 1.8 to 2.5 at 500 nm and a QWOT of 1.1 to 3.5, as shown in Fig. 2. The refractive index of the H1 layer is preferably 1.9 to 2.5, more preferably 2.0 to 2.5, and even more preferably 2.1 to 2.5.

[0072] As shown in FIG. 2, when the H1 layer closest to the resin film is defined as the first H1 layer, the first dielectric multilayer film preferably includes a first M1 layer between the first H1 layer and the resin film, the first M1 layer being made up of multiple continuous layers, the sum of the QWOT of each layer satisfying the range of 1.2 to 1.8.

[0073] That is, just as the second dielectric multilayer film has a configuration including a first H2 layer and a first M2 layer, the first dielectric multilayer film also preferably includes a first H1 layer and a first M1 layer. With the above configuration of the first dielectric multilayer film, the first M1 layer functions as an intermediate refractive index layer and the spectral waveform becomes smooth, so that reflection is further suppressed in a wide wavelength range from the visible light region to the infrared light region when light is incident from the resin surface of the optical filter.

[0074] More specifically, the first dielectric multilayer film has the above-mentioned configuration, and thus the following characteristics are obtained. (i-13) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-14) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-16) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5%

[0075] The first M1 layer may be disposed at any position between the first H1 layer and the resin film. Specifically, in FIG. 2, the first M1 layer is composed of all layers (first to fourth layers) included between the resin film and the first H1 layer, but the layer (first layer) closest to the resin film to the third layer (third layer) may be the first M1 layer (in this case, the sum of the QWOTs of the first to third layers is 1.423), and the layer closest to the first H1 layer, SiO2 (fourth layer), may be an arbitrary layer.

[0076] In addition, when there are multiple single layers whose QWOT is 1.2 or more and 1.8 or multiple consecutive layers whose total QWOT is 1.2 or more and 1.8 or less between the first H1 layer and the resin film, any one of the single layers or multiple consecutive layers is designated as the first M1 layer, and the other layers are designated as any layer.

[0077] In this way, an optional layer may be included between the first H1 layer and the resin layer, as long as it does not impede the effects of the present invention. For example, the optional layer may be included between the resin layer and the first M1 layer, or between the first M1 layer and the first H1 layer. The optional layer may be the same as those described above.

[0078] Furthermore, as shown in Fig. 3, the first dielectric multilayer film may include two or more H1 layers. In this case, when the layer second closest to the resin film is the second H1 layer, it is preferable to include a second M1 layer between the first H1 layer and the second H1 layer, the second M1 layer being made up of multiple continuous layers whose total QWOT is 1.2 to 2.1. By having the second M1 layer between the first H2 layer and the second H2 layer, the second M1 layer functions as an intermediate refractive index layer and the spectral waveform becomes smooth, so that reflection is further suppressed when light is incident from the resin surface of the optical filter.

[0079] The second M1 layer may be composed of any number of layers as long as the sum of the QWOT of each layer is 1.2 or more and 2.1 or less. That is, the second M1 layer may be a single layer that satisfies the QWOT of 1.2 or more and 2.1 or less. However, from the viewpoint of improving productivity, the second M1 layer is preferably composed of 6 layers or less, and more preferably 3 layers or less.

[0080] Furthermore, in this embodiment, as shown in Fig. 4, it is preferable to include two single layers having a QWOT of 1.2 to 2.1 or two consecutive layers having a total QWOT of 1.2 to 2.1 between the first H1 layer and the second H1 layer. In this case, the layer closest to the second H1 layer among the corresponding single layers or consecutive layers is the second M1 layer, and the layer second closest to the second H1 layer is the third M1 layer. That is, it is preferable that the first dielectric multilayer film includes, in addition to the second M1 layer, a third M1 layer consisting of a single layer having a QWOT of 1.2 to 2.1 or a plurality of layers having a total QWOT of 1.2 to 2.1 between the first H1 layer and the second M1 layer.

[0081] Because the first dielectric multilayer film has this configuration, the third M1 layer functions as an intermediate refractive index layer, smoothing the spectral waveform, thereby further suppressing reflection over a wide wavelength range from the visible light region to the near-infrared light region.

[0082] The second M1 layer and the third M1 layer may be disposed at any position, so long as the layer closest to the second H1 layer is the second M1 layer, as described above.

[0083] In the example shown in Figure 4, there are two single layers (the second M1 layer and the third M1 layer) between the first H1 layer and the second H1 layer that satisfy a QWOT of 1.2 or more and 2.1 or two consecutive layers whose total QWOT is 1.2 or more and 2.1 or less, but three or more such single layers or layers may be included.

[0084] In addition, between the first H1 layer and the second H1 layer, an optional layer may be included in addition to the second M1 layer and the third M1 layer, as long as the effect of the present invention is not hindered. The optional layer may be the same as that described above. However, from the viewpoint of improving productivity, it is preferable that no optional layer is present. That is, it is most preferable that the second H1 layer, the second M1 layer, the third M1 layer, and the first H1 layer are formed continuously. Even if there is no third M1 layer, it is preferable that no optional layer is present, and the second H1 layer, the second M1 layer and the first H1 layer are formed continuously.

[0085] From the viewpoint of further suppressing reflection, it is preferable that the QWOT of the first H1 layer and the second H1 layer in the first dielectric multilayer film are different from each other. From the same viewpoint, it is preferable that the QWOT of the single layer constituting the first M1 layer, the second M1 layer and the third M1 layer or the total value of the QWOT of multiple consecutive layers are different from each other.

[0086] The total number of laminated dielectric layers in the first dielectric multilayer film is preferably 10 to 30, and more preferably 10 to 20. When the total number of laminated layers is within the above range, an increase in the film thickness per layer can be prevented.

[0087] The total thickness of the first dielectric multilayer film is preferably 0.5 to 2.0 μm, and more preferably 0.5 to 1.0 μm. When the thickness of the first dielectric multilayer film is within the above range, an increase in the thickness of each layer can be prevented.

[0088] <Phosphate glass> It is preferable that the phosphate glass satisfies all of the following spectroscopic properties (ii-1) to (ii-3). (ii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 92% (ii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE More than 90% (ii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 625 to 650 nm. (ii-4) Average internal transmittance T at wavelength 750~1000nm 750-1000AVE is 2.5% or less (ii-5) Average internal transmittance T at wavelength 1000~1200nm 1000-1200AVE Less than 7%

[0089] Satisfying the spectral characteristic (ii-1) means that the transmittance is excellent in the blue light region, and satisfying the spectral characteristic (ii-2) means that the transmittance is excellent in the visible light region of 450 to 600 nm. Internal transmittance T 450 is more preferably 93% or more, and further preferably 95% or more. Average internal transmittance T 450-600AVE is more preferably 94% or more, and further preferably 95% or more.

[0090] Satisfying the spectral characteristic (ii-3) means that it is possible to block light in the near-infrared region and efficiently capture visible transmitted light. The wavelength IR50 is more preferably in the range of 625 to 645 nm, and further preferably in the range of 625 to 640 nm.

[0091] Satisfying the spectral characteristic (ii-4) means that the film has excellent light-shielding properties in the near-infrared light region of 750 to 1000 nm. T 750-1000AVE is more preferably 2% or less, and further preferably 1.2% or less.

[0092] By satisfying the spectral characteristic (ii-5), it means that the film has excellent light-shielding properties in the near-infrared region of 1000 to 1200 nm. 1000-1200AVE is more preferably 6.8% or less, and further preferably 6.5% or less.

[0093] In the present invention, it is preferable that the phosphate glass starts absorbing near-infrared light in the region of 625 to 650 nm as shown in the above characteristic (ii-3), and exhibits high light-shielding properties beyond 750 nm as shown in the above characteristic (ii-4), thereby obtaining a substrate that can supplement the light-shielding properties of the above-mentioned dielectric multilayer film.

[0094] In the present invention, phosphate glass means glass containing 40% or more P2O5 expressed as a mass percentage based on oxide. Phosphate glass preferably contains copper ions. By containing copper ions that absorb light with a wavelength of about 900 nm, near-infrared light with a wavelength of 700 to 1200 nm can be blocked. Phosphate glass also includes silicophosphate glass in which part of the glass skeleton is composed of SiO2.

[0095] For example, it is preferable that the phosphate glass contains the following glass-constituting components: The content of each of the following glass-constituting components is expressed as mass percentage based on the oxide. P2O5 40-80% Al2O30.5~20% ΣR2O (where R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O, ΣR2O is the total amount of R2O) 0.5~20%ΣR'O (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, ΣR'O is the total amount of R'O) 0~40%CuO 0.5~40%

[0096] P2O5 is a main component forming glass and is a component for enhancing near-infrared cutoff properties. If the content of P2O5 is 40% or more, the effect is sufficiently obtained, and if it is 80% or less, problems such as glass becoming unstable and weather resistance decreasing are unlikely to occur. Therefore, the content is preferably 40 to 80%, more preferably 45 to 78%, even more preferably 50 to 77%, even more preferably 55 to 76%, and most preferably 60 to 75%.

[0097] Al2O3 is a main component forming glass, and is a component for increasing the strength of glass, increasing the weather resistance of glass, etc. If the content of Al2O3 is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, problems such as glass becoming unstable and deterioration of near-infrared cutoff properties are unlikely to occur. Therefore, the content is preferably 0.5 to 20%, more preferably 1.0 to 20%, even more preferably 2.0 to 18%, even more preferably 3.0 to 17%, particularly preferably 4.0 to 16%, and most preferably 5.0 to 15.5%.

[0098] R2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O) is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, and the like. If the total amount of R2O (ΣR2O) is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, the glass is less likely to become unstable, which is preferable. Therefore, it is preferably 0.5 to 20%, more preferably 1.0 to 19%, even more preferably 1.5 to 18%, even more preferably 2.0 to 17%, particularly preferably 2.5 to 16%, and most preferably 3.0 to 15.5%.

[0099] Li2O is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. The Li2O content is preferably 0 to 15%. If the Li2O content is 15% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur, which is preferable. The Li2O content is more preferably 0 to 8%, even more preferably 0 to 7%, even more preferably 0 to 6%, and most preferably 0 to 5%.

[0100] Na2O is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. The Na2O content is preferably 0 to 15%. If the Na2O content is 15% or less, the glass is less likely to become unstable, which is preferable. The Na2O content is more preferably 0.5 to 14%, further preferably 1 to 13%, even more preferably 2 to 13%, and most preferably 3 to 13%.

[0101] K2O is a component that has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The content of K2O is preferably 0 to 20%. If the content of K2O is 20% or less, the glass is less likely to become unstable, which is preferable. The content of K2O is more preferably 0.5 to 19%, further preferably 1 to 18%, further more preferably 2 to 17%, and most preferably 3 to 16%.

[0102] Rb2O is a component that has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The content of Rb2O is preferably 0 to 15%. If the content of Rb2O is 15% or less, the glass is less likely to become unstable, which is preferable. The content of Rb2O is more preferably 0.5 to 14%, further preferably 1 to 13%, further more preferably 2 to 13%, and most preferably 3 to 13%.

[0103] Cs2O is a component that has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The content of Cs2O is preferably 0 to 15%. If the content of Cs2O is 15% or less, the glass is less likely to become unstable, which is preferable. The content of Cs2O is more preferably 0.5 to 14%, further preferably 1 to 13%, further more preferably 2 to 13%, and most preferably 3 to 13%.

[0104] In addition, when two or more types of alkali metal components represented by R2O are added at the same time, a mixed alkali effect occurs in the glass, and R + The mobility of ions is reduced, so that when the glass comes into contact with water, the H+ Ions and R in glass + The hydration reaction caused by the ion exchange is inhibited, and the weather resistance of the glass is improved. Therefore, the phosphate glass of the present embodiment preferably contains two or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O. In this case, the total amount (ΣR2O) of R2O (where R2O is Li2O, Na2O, K2O, Rb2O, and Cs2O) is preferably more than 7% and not more than 18%. If the total amount of R2O is more than 7%, the effect is sufficiently obtained, and if it is 18% or less, problems such as glass instability, deterioration of near-infrared cutoff property, and deterioration of glass strength are unlikely to occur, which is preferable. Therefore, ΣR2O is preferably more than 7% and not more than 18%, more preferably 7.5 to 17%, even more preferably 8 to 16%, even more preferably 8.5 to 15%, and most preferably 9 to 14%.

[0105] R'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO) is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, increasing the strength of glass, etc. The total amount of R'O (ΣR'O) is preferably 0 to 40%. If the total amount of R'O is 40% or less, problems such as glass becoming unstable, reduced near-infrared cutoff property, and reduced strength of glass are unlikely to occur, which is preferable. It is more preferably 0 to 35%, further preferably 0 to 30%. It is still more preferably 0 to 25%, particularly preferably 0 to 20%, and most preferably 0 to 15%.

[0106] CaO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, and increasing the strength of glass. The CaO content is preferably 0 to 10%. If the CaO content is 10% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur, which is preferable. The CaO content is more preferably 0 to 8%, even more preferably 0 to 6%, even more preferably 0 to 5%, and most preferably 0 to 4%.

[0107] MgO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, and increasing the strength of glass. The content of MgO is preferably 0 to 15%. If the content of MgO is 15% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur, which is preferable. The content of MgO is more preferably 0 to 13%, further preferably 0 to 10%, further more preferably 0 to 9%, and most preferably 0 to 8%.

[0108] BaO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. The content of BaO is preferably 0 to 40%. If the content of BaO is 40% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur, which is preferable. The content of BaO is more preferably 0 to 30%, further preferably 0 to 20%, further more preferably 0 to 10%, and most preferably 0 to 5%.

[0109] SrO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. The SrO content is preferably 0 to 10%. If the SrO content is 10% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur, which is preferable. The SrO content is more preferably 0 to 8%, further preferably 0 to 7%, and most preferably 0 to 6%.

[0110] ZnO has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The ZnO content is preferably 0 to 15%. If the ZnO content is 15% or less, problems such as glass instability, deterioration of glass melting property, and deterioration of near-infrared cutoff property are unlikely to occur, which is preferable. The ZnO content is more preferably 0 to 13%, further preferably 0 to 10%, further more preferably 0 to 9%, and most preferably 0 to 8%.

[0111] CuO is a component for improving the near-infrared cutoff property. The CuO content is preferably 0.5 to 40%. If the CuO content is 0.5% or more, the effect can be sufficiently obtained, and if the CuO content is 40% or less, problems such as the generation of devitrification in the glass and a decrease in the transmittance of light in the visible region are unlikely to occur, which is preferable. The CuO content is more preferably 1.0 to 35%, even more preferably 1.5 to 30%, even more preferably 2.0 to 25%, and most preferably 2.5 to 20%.

[0112] In the phosphate glass according to this embodiment, F may be contained in a range of 10% or less to improve weather resistance. If the F content is 10% or less, problems such as a decrease in near-infrared cutoff property and generation of devitrified foreign matter in the glass are unlikely to occur, which is preferable. The F content is more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0113] B2O3 may be contained in the range of 10% or less to stabilize the glass. If the content of B2O3 is 10% or less, problems such as deterioration of the weather resistance of the glass and deterioration of the near-infrared cutoff property are unlikely to occur, which is preferable. It is more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0114] In this embodiment, SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, MoO3, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 may be contained in a range of 5% or less to improve the weather resistance of the phosphate glass. If the content of these components is 5% or less, problems such as devitrification of the glass and deterioration of the near-infrared cutoff property are unlikely to occur, which is preferable. It is preferably 4% or less, more preferably 3% or less, even more preferably 2% or less, and even more preferably 1% or less.

[0115] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2 and CoO are all components that, when present in phosphate glass, reduce the transmittance of light in the visible region, and therefore it is preferable that these components are not substantially contained in the glass. In the present invention, "substantially free of a specific component" means that the component is not intentionally added, and does not exclude the component being unavoidably mixed in from raw materials, etc., to the extent that it does not affect the desired properties.

[0116] The thickness of the phosphate glass is preferably 0.5 mm or less, more preferably 0.3 mm or less, from the viewpoint of reducing the height of the camera module, and is preferably 0.1 mm or more, more preferably 0.15 mm or more, from the viewpoint of maintaining the strength of the element.

[0117] The phosphate glass can be produced, for example, as follows. First, the raw materials are weighed and mixed so as to obtain the above composition range (mixing process). This raw material mixture is placed in a platinum crucible and heated and melted at a temperature of 700 to 1400°C in an electric furnace (melting process). After thorough stirring and clarification, it is cast into a metal mold, cut, polished and formed into a plate of the specified thickness (molding process).

[0118] In the melting step of the above manufacturing method, the highest temperature of the glass during melting is preferably 1400°C or less. If the highest temperature of the glass during melting exceeds the above temperature, the transmittance characteristics may deteriorate. The above temperature is more preferably 1350°C or less, further preferably 1300°C or less, and even more preferably 1250°C or less. Furthermore, if the temperature in the melting step is too low, problems such as devitrification during melting and a long time required for melting through may occur, so the temperature is preferably 700°C or higher, more preferably 800°C or higher.

[0119] <Resin film> The resin film in the optical filter of the present invention contains a resin and a near-infrared absorbing dye having a maximum absorption wavelength in the range of 690 to 800 nm in the resin, where the resin refers to the resin that constitutes the resin film.

[0120] It is preferable that the resin film satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 85% (iii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE More than 90% (iii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 660 to 700 nm.

[0121] Satisfying the spectral characteristic (iii-1) means that the transmittance in the blue light region is excellent. Internal transmittance T 450 is more preferably 87% or more, and further preferably 90% or more.

[0122] Satisfying the spectral characteristic (iii-2) means that the transmittance in the visible light region of 450 to 600 nm is excellent. Average internal transmittance T 450-600AVE is more preferably 93% or more, and further preferably 95%.

[0123] By satisfying the spectral characteristic (iii-3), when used in combination with the above-mentioned phosphate glass, an optical filter can be obtained in which the incidence angle dependency of the spectral characteristics is suppressed in the range of 630 to 680 nm. The wavelength IR50 is more preferably in the range of 660 to 690 nm, and further preferably in the range of 665 to 685 nm.

[0124] The resin film in the present invention contains a dye having a maximum absorption wavelength in the range of 690 to 800 nm, and thus can block the near infrared region around 700 nm, where phosphate glass has a slightly weak light blocking effect, due to the absorption characteristics of the dye.

[0125] The near infrared absorbing dye may be, for example, at least one selected from the group consisting of cyanine dyes, phthalocyanine dyes, squarylium dyes, naphthalocyanine dyes, and diimonium dyes, and may be used alone or in combination. Among these, squarylium dyes and cyanine dyes are preferred from the viewpoint of easily achieving the effects of the present invention.

[0126] The content of the near infrared absorbing dye in the resin film is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the resin. When two or more types of compounds are combined, the above content is the total of the respective compounds.

[0127] The resin film may contain other dyes, for example, ultraviolet light absorbing dyes, to the extent that the effect of the present invention is not impaired. Examples of ultraviolet light absorbing dyes include oxazole dyes, merocyanine dyes, cyanine dyes, naphthalimide dyes, oxadiazole dyes, oxazine dyes, oxazolidine dyes, naphthalic acid dyes, styryl dyes, anthracene dyes, cyclic carbonyl dyes, and triazole dyes. Among these, merocyanine dyes are particularly preferred. In addition, one type may be used alone, or two or more types may be used in combination.

[0128] The resin is not limited as long as it is a transparent resin, and one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamideimide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, polystyrene resin, etc. may be used. One of these resins may be used alone, or two or more may be used in combination. From the viewpoints of the spectral characteristics, glass transition point (Tg) and adhesion of the resin film, one or more resins selected from polyimide resins, polycarbonate resins, polyester resins and acrylic resins are preferred.

[0129] When a plurality of dyes are used, they may be contained in the same resin film, or each may be contained in a different resin film.

[0130] The resin film can be formed by dissolving or dispersing the dye, the resin or the raw material component of the resin, and each component that is mixed as necessary in a solvent to prepare a coating liquid, applying this to a support, drying it, and further curing it as necessary. The support in this case may be the phosphate glass used in this filter, or a peelable support that is used only when forming the resin film. The solvent may be a dispersion medium that can be stably dispersed or a solvent that can dissolve the material.

[0131] The coating liquid may also contain a surfactant to improve voids caused by microbubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For example, a dip coating method, a cast coating method, or a spin coating method can be used for coating the coating liquid. After the coating liquid is applied onto a support, a resin film is formed by drying. When the coating liquid contains raw materials for a transparent resin, a curing process such as heat curing or light curing is further performed.

[0132] The resin film can also be produced in a film shape by extrusion molding. The resulting film-shaped resin film can be laminated on phosphate glass and integrated by thermocompression bonding or the like to produce a substrate.

[0133] The optical filter may have one or more resin layers in it. When the optical filter has two or more resin layers, the layers may have the same or different configurations.

[0134] The thickness of the resin film is preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of the in-plane film thickness distribution in the substrate after coating and the appearance quality, and is preferably 0.5 μm or more, from the viewpoint of expressing the desired spectral characteristics at an appropriate dye concentration. When the optical filter has two or more resin films, it is preferable that the total thickness of each resin film is within the above range.

[0135] <Other> The filter may also include other components (layers) that absorb light using inorganic particles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, lanthanum boride, etc. ITO particles and cesium tungstate particles have high visible light transmittance and light absorption over a wide range of infrared wavelengths exceeding 1200 nm, and therefore can be used when such infrared light shielding is required.

[0136] As described above, this specification discloses the following optical filters, etc. [1] An optical filter comprising, in this order, a first dielectric multilayer film, a resin film, phosphate glass, and a second dielectric multilayer film, The resin film contains a resin and a dye having a maximum absorption wavelength in the resin of 690 to 800 nm, the first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers having different refractive indices; The second dielectric multilayer film includes at least one H2 layer having a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less; When the layer closest to the phosphate glass among the H2 layers is defined as a first H2 layer, a first M2 layer between the first H2 layer and the phosphate glass, the first M2 layer being a single layer having a QWOT of 1.2 to 1.8 or a plurality of layers having a total QWOT of 1.2 to 1.8; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-4). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 450-550(0deg)AVE More than 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 450-550(50deg)AVE More than 85% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T750-1000(0deg)AVE is 2.5% or less (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE is 2.5% or less [2] An optical filter comprising, in this order, a first dielectric multilayer film, a resin film, phosphate glass, and a second dielectric multilayer film, The resin film contains a resin and a dye having a maximum absorption wavelength in the resin of 690 to 800 nm, the first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers having different refractive indices; the first dielectric multilayer film includes at least one H1 layer having a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less; When the layer closest to the resin film among the H1 layers is defined as a first H1 layer, a first M1 layer between the first H1 layer and the resin film, the first M1 layer being a single layer having a QWOT of 1.2 or more and 1.8 or a plurality of layers having a total QWOT of 1.2 or more and 1.8 or less; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-4). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 450-550(0deg)AVE More than 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 450-550(50deg)AVE More than 85% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE is 2.5% or less (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE is 2.5% or less [3] The optical filter according to [1], further satisfying the following spectral characteristics (i-5) to (i-8). (i-5) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-6) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-7) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-8) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5% [4] The optical filter according to any one of [1] to [3], further satisfying the following spectral characteristics (i-9) to (i-12). (i-9) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 1000-1200(0deg)AVE Less than 7% (i-10) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 1000-1200(50deg)AVE Less than 7% (i-11) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 at which the transmittance is 30% (0deg) But the wavelength is 630~680nm. (i-12) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 at which the transmittance is 30% (50deg) But the wavelength is 630~680nm. [5] The first dielectric multilayer film includes at least one H1 layer having a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5; When the layer closest to the resin film among the H1 layers is defined as a first H1 layer, The optical filter according to any one of [1], [3] and [4], characterized in that a first M1 layer consisting of a single layer having a QWOT of 1.2 or more and 1.8 or a plurality of layers having a total QWOT of 1.2 or more and 1.8 or less is included between the first H1 layer and the resin film. [6] The second dielectric multilayer film includes at least one H2 layer having a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5; When the layer closest to the phosphate glass among the H2 layers is defined as a first H2 layer, The optical filter according to [2], characterized in that it includes a first M2 layer between the first H2 layer and the phosphate glass, the first M2 layer being a single layer having a QWOT of 1.2 or more and 1.8 or a plurality of layers having a total QWOT of 1.2 or more and 1.8 or less. [7] The optical filter according to [5], further satisfying the following spectral characteristics (i-13) to (i-16). (i-13) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees 750-1000(5deg)AVE Less than 3% (i-14) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees 450-600(5deg)AVE Less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees 750-1000(50deg)AVE Less than 5% (i-16) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 at a wavelength of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE Less than 5% [8] The optical filter according to any one of [1] to [7], further satisfying the following spectral characteristics (i-17) to (i-20). (i-17) The average transmittance T 450-550(0deg)AVE and the average transmittance T 450-550(50deg)AVE The absolute value of the difference is 3.5% or less (i-18) The average transmittance T 750-1000(0deg)AVE and the average transmittance T 750-1000(50deg)AVE The absolute value of the difference is 1.5% or less (i-19) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 1000-1200(0deg)AVEIn the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T 1000-1200(50deg)AVE The absolute value of the difference is 1.5% or less (i-20) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 at which the transmittance is 30% (0deg) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 at which the transmittance is 30% (50deg) The absolute value of the difference is 15 nm or less [9] The optical filter according to any one of [1] to [8], further satisfying the following spectral characteristic (i-21): (i-21) When the second dielectric multilayer film side is the incident direction, the average absorption loss amount defined below is 95% or more in the wavelength range of 750 to 1000 nm. (Absorption loss) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees)

[10] The optical filter according to any one of [1] to [9], further satisfying the following spectral characteristic (i-22): (i-22) When the second dielectric multilayer film side is the incident direction, in the wavelength range of 750 to 1000 nm, the minimum value of the absorption loss amount defined below is 90% or more (absorption loss amount) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectance at an incident angle of 5 degrees)

[11] The optical filter according to any one of [1] to

[10] , further satisfying the following spectral characteristic (i-23): (i-23) When the second dielectric multilayer film side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the reflectance R2 for each wavelength is 1 nm intervals from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R2 n(5deg) However, there are more than 200 n values ​​for which the probability is less than 1%.

[12] The optical filter according to any one of [5] to

[11] , further satisfying the following spectral characteristic (i-24): (i-24) When the first dielectric multilayer film side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the reflectance R1 for each wavelength is 1 nm intervals from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg)When (n: any integer) is read, the reflectance R1 n(5deg) However, there are more than 150 n values ​​for which the probability is less than 1%.

[13] The second dielectric multilayer film includes two or more of the H2 layers; When the layer second closest to the phosphate glass among the H2 layers is defined as a second H2 layer, The optical filter according to any one of [1], [3] to [5], and [7] to

[12] , further comprising a second M2 layer between the first H2 layer and the second H2 layer, the second M2 layer being a single layer having a QWOT of 1.2 or more and 2.1 or a plurality of layers having a total QWOT of 1.2 or more and 2.1 or less.

[14] The optical filter described in

[13] , wherein the second dielectric multilayer film includes a third M2 layer between the first H2 layer and the second M2 layer, the third M2 layer being a single layer having a QWOT of 1.2 or more and 2.1 or more, or a plurality of layers having a total QWOT of 1.2 or more and 2.1 or less.

[15] The optical filter according to any one of [1] to

[14] , wherein the phosphate glass satisfies all of the following spectral characteristics (ii-1) to (ii-5): (ii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 92% (ii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE More than 90% (ii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 625 to 650 nm. (ii-4) Average internal transmittance T at wavelength 750~1000nm 750-1000AVE is 2.5% or less (ii-5) Average internal transmittance T at wavelength 1000~1200nm 1000-1200AVE Less than 7%

[16] The optical filter according to any one of [1] to

[15] , wherein the resin film satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 85% (iii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE More than 90% (iii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 660 to 700 nm.

[17] The phosphate glass, expressed as a mass percentage based on oxides, P2O5 40-80% Al2O30.5~20% ΣR2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O, and ΣR2O is the total amount of R2O) 0.5~20% ΣR'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR'O is the total amount of R'O) 0~40% CuO 0.5~40% The optical filter according to any one of [1] to

[16] , having a composition comprising:

[18] The optical filter according to any one of [1] to

[17] , wherein the resin film has a thickness of 10 μm or less. EXAMPLES

[0137] The present invention will now be described in more detail with reference to examples. The spectral characteristics were measured using an ultraviolet-visible spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation). Unless the angle of incidence is specifically stated, the spectral characteristics are values ​​measured at an angle of incidence of 0° (perpendicular to the principal surface of the optical filter).

[0138] The dyes used in each example are as follows: Compound 1 (squarylium compound): Synthesized based on WO 2017 / 135359. Compound 2 (merocyanine compound): Synthesized based on the specification of German Patent Publication No. 10109243. Compound 3 (cyanine compound): Synthesized according to the method described in Dyes and Pigments, 73, 344-352 (2007). Compound 4 (squarylium compound): Synthesized based on the method described in JP 2017-110209 A.

[0139] [ka]

[0140] <Spectral characteristics of dyes in resin> A polyimide resin ("C3G30G" (product name) manufactured by Mitsubishi Gas Chemical Company, Inc., refractive index 1.59) was dissolved in γ-butyrolactone (GBL):cyclohexanone = 1:1 (mass ratio) to prepare a polyimide resin solution with a resin concentration of 8.5 mass %. Each of the dyes of the above compounds 1 to 4 was added to the resin solution at a concentration of 7.5 parts by mass per 100 parts by mass of the resin, and the mixture was stirred and dissolved for 2 hours at 50° C. to obtain a coating liquid. The obtained coating liquid was applied to an alkaline glass (manufactured by SCHOTT, D263 glass, thickness 0.2 mm) by spin coating to form a coating film having a thickness of approximately 1.0 μm. The spectral transmittance curve of the obtained coating film was measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The following table shows the spectral properties of each of the above compounds 1 to 4 in a polyimide resin. Note that the spectral properties shown in the following table were evaluated by internal transmittance in order to avoid the influence of reflection at the air interface and the glass interface.

[0141] [Table 1]

[0142] <Examples 1-1 to 1-2: Spectral characteristics of resin film> Any of the dyes of Compounds 1 to 4 was mixed in the polyimide resin solution (Mitsubishi Gas Chemical Company, C3G30G) prepared in the same manner as when calculating the spectroscopic properties of the above compounds, at the concentrations shown in the table below, and the mixture was stirred and dissolved at 50° C. for 2 hours to obtain a resin solution. The obtained resin solution was applied to alkaline glass (SCHOTT Corporation, D263 glass, thickness 0.2 mm) by spin coating to form a resin film with a thickness of 1.0 μm. The spectral transmittance curve of the obtained resin film was measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The obtained spectral characteristics are shown in the following table. Note that the spectral characteristics shown in the following table were evaluated based on the internal transmittance in order to avoid the influence of reflection at the air interface and the glass interface. Incidentally, Examples 1-1 and 1-2 are reference examples.

[0143] [Table 2]

[0144] <Spectral properties of glass> Phosphate glass 1 and phosphate glass 2 were prepared as phosphate glasses by the following procedure. The raw materials were weighed and mixed to obtain the composition shown in the table below (mass % based on oxides), placed in a crucible with an internal volume of about 400cc, and melted in an air atmosphere for 2 hours.The mixture was then clarified, stirred, and poured into a rectangular mold with dimensions of 100mm length x 80mm width x 20mm height that had been preheated to about 300℃-500℃, and then slowly cooled at a rate of about 1℃ / min to form a plate with dimensions of 40mm length x 30mm width and thickness shown in Table 4. Both sides were optically polished to obtain a plate-shaped glass. In addition, NF50T manufactured by AGC was prepared as fluorophosphate glass 1 and fluorophosphate glass 2. The thicknesses of fluorophosphate glass 1 and fluorophosphate glass 2 are shown in Table 4.

[0145] [Table 3]

[0146] For each glass, the spectral transmittance curve was measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The obtained spectral characteristics are shown in the table below. Note that the spectral characteristics shown in the table below were evaluated using internal transmittance to avoid the influence of reflection at the air interface and the glass interface. The obtained results are shown in the table below. In addition, the haze of each glass was determined based on JIS K 7136 using an automatic haze meter (manufactured by Tokyo Denshoku Industries, model number: TC-HIIIDPK). Moreover, the spectral transmittance curves of phosphate glass 1 and fluorophosphate glass 1 are shown in FIG.

[0147] [Table 4]

[0148] From the above results, it was found that phosphate glass 1 and phosphate glass 2, which have specific glass compositions, have higher transmittance in the visible light region and higher light blocking properties in the near-infrared region than fluorophosphate glass 1 and fluorophosphate glass 2. Furthermore, phosphate glass 1 and phosphate glass 2, which have specific glass compositions, had low haze. On the other hand, fluorophosphate glass 1 and fluorophosphate glass 2 maintained high visible transmittance but had poor infrared light blocking properties. In addition, the glass plate thickness was increased to improve light blocking properties, but the IR50 wavelength was on the short wavelength side, and the desired spectral characteristics were not achieved.

[0149] <Example 2-1 to Example 2-8: Optical filter configuration> [Example 2-1] On one main surface of the above phosphate glass 1 (thickness: 0.28 mm), layers were deposited in order from the first layer by vapor deposition so that the material and thickness (nm) of each layer were as shown in the table below, forming a total of eight layers of the second dielectric multilayer film. Hereinafter, the dielectric multilayer film having the composition shown in Table 5 will be referred to as "dielectric multilayer film 1".

[0150] [Table 5]

[0151] A resin film was formed on the main surface of the phosphate glass 1 in the same manner as in Example 1-1. Next, a dielectric multilayer film 1 was formed as a first dielectric multilayer film on the surface of the resin film by deposition, to obtain an optical filter of Example 2-1. The configuration of the optical filter of Example 2-1 is shown in Table 10 and FIG. 2. In addition, when the dielectric multilayer 1 is formed on the second dielectric multilayer, the H layer / M layer column in Table 5 is considered as H2 layer / M2 layer, and when it is formed on the first dielectric multilayer, it is considered as H1 layer / M1 layer. The same applies to the following tables.

[0152] [Example 2-2] An optical filter was produced in the same manner as in Example 2-1, except that the first and second dielectric multilayer films were formed as shown in the table below. Hereinafter, the dielectric multilayer film having the configuration shown in Table 6 will be referred to as "dielectric multilayer film 2." The configuration of the optical filter of Example 2-2 is shown in Table 10 and FIG. 3.

[0153] [Table 6]

[0154] [Example 2-3] An optical filter was produced in the same manner as in Example 2-1, except that the first and second dielectric multilayer films were formed as shown in the table below. Hereinafter, the dielectric multilayer film having the configuration shown in Table 7 will be referred to as "Dielectric Multilayer Film 3." The configuration of the optical filter of Example 2-3 is shown in Table 10 and FIG. 4.

[0155] [Table 7]

[0156] [Example 2-4] An optical filter was produced in the same manner as in Example 2-1, except that a dielectric multilayer film having the configuration shown in the table below was formed as the first dielectric multilayer film. Hereinafter, the dielectric multilayer film having the configuration shown in Table 8 will be referred to as "Dielectric Multilayer Film 4." The configuration of the optical filter of Example 2-4 is shown in Table 10.

[0157] [Table 8]

[0158] [Example 2-5] An optical filter was produced in the same manner as in Example 2-4, except that the dielectric multilayer film 4 was formed as the second dielectric multilayer film. The configuration of the optical filter in Example 2-5 is shown in Table 11.

[0159] [Example 2-6] An optical filter was produced in the same manner as in Example 2-4, except that fluorophosphate glass 1 was used as the phosphate glass, the resin film of Example 1-2 was formed as the resin film, and a dielectric multilayer film having the configuration shown in the table below was formed as the second dielectric multilayer film. Hereinafter, the dielectric multilayer film having the configuration shown in Table 9 will be referred to as "dielectric multilayer film 5." Table 11 shows the configuration of the optical filter of Example 2-6.

[0160] [Table 9]

[0161] [Example 2-7] An optical filter was produced in the same manner as in Example 2-6, except that the dielectric multilayer film 1 was formed as the first dielectric multilayer film. The configuration of the optical filter in Example 2-7 is shown in Table 11.

[0162] [Example 2-8] An optical filter was produced in the same manner as in Example 2-1, except that fluorophosphate glass was used as the phosphate glass. The configuration of the optical filter in Example 2-8 is shown in Table 11.

[0163] <Example 2-1 to Example 2-8: Spectral characteristics of optical filters> For the optical filters of Examples 2-1 to 2-8 above, the spectral transmittance curves at incident angles of 0 degrees and 50 degrees and the spectral reflectance curves at incident angles of 5 degrees and 50 degrees in the wavelength range of 350 to 1200 nm were measured using an ultraviolet-visible spectrophotometer. In measuring the spectral reflectance curves, the case where the second dielectric multilayer film side is the incident direction is referred to as the "front surface", and the case where the first dielectric multilayer film side is the incident direction is referred to as the "rear surface". From the obtained data of spectral characteristics, the various characteristics shown in the table below were calculated. In addition, the spectral transmittance curves (incident angles of 0 degrees and 50 degrees) of the optical filters of Examples 2-1, 2-4, 2-5, and 2-6, and the reflectance curves (incident angles of 5 degrees and 50 degrees) when the second dielectric multilayer film side is the incident direction, are shown in Figures 6 to 13. Examples 2-1 to 2-4 are working examples, and Examples 2-5 to 2-8 are comparative examples.

[0164] [Table 10]

[0165] [Table 11]

[0166] From the above results, it can be seen that the optical filters of Examples 2-1 to 2-4, which are embodiments, have high transmittance in the visible light region and high shielding properties in the near-infrared light region compared to Examples 2-5 to 2-8, which are comparative examples, and since the change in visible light transmittance is small even at high angles of incidence, the occurrence of ripples is suppressed, and further, since the reflectance is small at both incidence surfaces, the occurrence of stray light is also suppressed. On the other hand, the optical filter of Example 2-5, which is a comparative example, had large reflection characteristics at both incident surfaces. Moreover, the optical filter of Example 2-6, which is a comparative example, had large reflection characteristics on both incident surfaces, was poor in light blocking properties in the near-infrared light region, and further had a large amount of absorption loss. Moreover, the optical filter of Example 2-7, which is a comparative example, had a large reflection characteristic when light was incident on the glass surface, was inferior in light blocking properties in the near-infrared region, and further had a large amount of absorption loss. Moreover, the optical filter of Example 2-8, which is a comparative example, was inferior in light blocking properties in the near-infrared light region.

[0167] Although the present invention has been described in detail and with reference to specific embodiments, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2022-138361) filed on August 31, 2022, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0168] 1B Optical Filter 11 Phosphate glass 12 Resin film 20A 2nd dielectric multilayer film 20B First dielectric multilayer film

Claims

1. An optical filter comprising a first dielectric multilayer film, a resin film, a phosphate glass, and a second dielectric multilayer film in this order, wherein the resin film contains a resin and a near-infrared absorbing dye, the first dielectric multilayer film and the second dielectric multilayer film each contain a plurality of layers having different refractive indices, The second dielectric multilayer film includes at least one H layer satisfying a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less. ２ and The above-mentioned H ２ Among the above-mentioned H layers, when the layer closest to the phosphate glass is defined as the first H ２ layer, the first H ２ a first M layer comprising a single layer satisfying 1.2 ≤ QWOT ≤ 1.8 or a plurality of layers satisfying 1.2 ≤ total QWOT ≤ 1.8 is provided between the first H layer and the phosphate glass ２ and includes and the optical filter satisfies all of the following spectral characteristics (i-9) to (i-10). (i-9) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T1000 - 1200(0deg)AVE at wavelengths of 1000 to 1200 nm is 7% or less (i-10) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T1000 - 1200(50deg)AVE at wavelengths of 1000 to 1200 nm is 7% or less

2. An optical filter comprising a first dielectric multilayer film, a resin film, a phosphate glass, and a second dielectric multilayer film in this order, wherein the resin film contains a resin and a near-infrared absorbing dye, the first dielectric multilayer film and the second dielectric multilayer film each contain a plurality of layers having different refractive indices, The first dielectric multilayer film includes at least one H layer satisfying a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less. １ and The said H １ Among the said H layers, when the layer closest to the resin film is defined as the first H １ layer, The first H １ Between the first H layer and the resin film, there is a first M layer composed of a single layer satisfying 1.2 ≤ QWOT ≤ 1.8 or a plurality of layers satisfying 1.2 ≤ total QWOT ≤ 1.8 １ including and the optical filter satisfies all of the following spectral characteristics (i-9) to (i-10). (i-9) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T1000 - 1200(0deg)AVE at wavelengths of 1000 to 1200 nm is 7% or less (i-10) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T1000 - 1200(50deg)AVE at wavelengths of 1000 to 1200 nm is 7% or less

3. The optical filter according to claim 1 or 2, further satisfying the following spectral characteristics (i-1) to (i-4). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T450 - 550(0deg)AVE at wavelengths of 450 to 550 nm is 85% or more (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T450 - 550(50deg)AVE at wavelengths of 450 to 550 nm is 85% or more (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T750 - 1000(0deg)AVE at wavelengths of 750 to 1000 nm is 2.5% or less (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T750 - 1000(50deg)AVE at wavelengths of 750 to 1000 nm is 2.5% or less

4. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-5) to (i-8). When the incident direction is the side of the second dielectric multilayer film, the average reflectance R2 at wavelengths of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees ７５０－１０００（５ｄｅｇ）ＡＶＥ is 3% or less When the incident direction is the side of the second dielectric multilayer film, the average reflectance R2 at wavelengths of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees ４５０－６００（５ｄｅｇ）ＡＶＥ is 3% or less When the incident direction is the side of the second dielectric multilayer film, the average reflectance R2 in the wavelength range of 750 to 1000 nm in the spectroscopic reflectance curve at an incident angle of 50 degrees ７５０－１０００（５０ｄｅｇ）ＡＶＥ is 5% or less When the incident direction is the side of the second dielectric multilayer film, the average reflectance R2 at wavelengths of 450 to 600 nm in the spectroscopic reflectance curve at an incident angle of 50 degrees ４５０－６００（５０ｄｅｇ）ＡＶＥ is 5% or less

5. The optical filter according to claim 1 or 2, further satisfying the following spectral characteristics (i-11) to (i-12). (i - 11) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 at which the transmittance becomes 30% （０ｄｅｇ） is in the wavelength range of 630 to 680 nm (i - 12) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 at which the transmittance becomes 30% （５０ｄｅｇ） is in the wavelength range of 630 to 680 nm

6. The first dielectric multilayer film includes at least one H layer satisfying a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less. １ and The above-mentioned H １ Among the above-mentioned H layers, when the layer closest to the resin film is defined as the first H １ layer, The first H １ Between the layer and the resin film, there is a first M layer composed of a single layer satisfying 1.2 ≤ QWOT ≤ 1.8 or a plurality of layers satisfying 1.2 ≤ total QWOT ≤ 1.8 １ The optical filter according to claim 1, characterized by including the layer

7. The optical filter according to claim 2, further satisfying the following spectral characteristics (i-13) to (i-16). When the incident direction is the side of the first dielectric multilayer film, the average reflectance R1 at wavelengths of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 5 degrees ７５０－１０００（５ｄｅｇ）ＡＶＥ is 3% or less When the incident direction is the side of the first dielectric multilayer film, the average reflectance R1 at wavelengths of 450 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees ４５０－６００（５ｄｅｇ）ＡＶＥ is 3% or less When the incident direction is the side of the first dielectric multilayer film, the average reflectance R1 at wavelengths of 750 to 1000 nm in the spectral reflectance curve at an incident angle of 50 degrees ７５０－１０００（５０ｄｅｇ）ＡＶＥ is 5% or less When the incident direction is the side of the first dielectric multilayer film, the average reflectance R1 at wavelengths of 450 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees ４５０－６００（５０ｄｅｇ）ＡＶＥ is 5% or less

8. The optical filter according to claim 1 or 2, further satisfying the following spectral characteristics (i-17) to (i-20). (i - 17) the average transmittance T ４５０－５５０（０ｄｅｇ）ＡＶＥ and the average transmittance T ４５０－５５０（５０ｄｅｇ）ＡＶＥ the absolute value of the difference is 3.5% or less (i - 18) the average transmittance T ７５０－１０００（０ｄｅｇ）ＡＶＥ and the average transmittance T ７５０－１０００（５０ｄｅｇ）ＡＶＥ has an absolute value of the difference of 1.5% or less In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T in the wavelength range of 1000 to 1200 nm １０００－１２００（０ｄｅｇ）ＡＶＥ and in the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T in the wavelength range of 1000 to 1200 nm １０００－１２００（５０ｄｅｇ）ＡＶＥ the absolute value of the difference is 1.5% or less In the spectral transmittance curve at an incident angle of 0 degrees (i - 20), the wavelength IR30 at which the transmittance becomes 30% （０ｄｅｇ） and, in the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 at which the transmittance becomes 30% （５０ｄｅｇ） The absolute value of the difference is 15 nm or less

9. The optical filter according to claim 1, further satisfying the following spectral characteristic (i-21). (i-21) When the incident direction is from the second dielectric multilayer film side, in the wavelength range of 750 to 1000 nm, the average of the absorption loss amounts defined below is 95% or more (Absorption loss amount) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectance at an incident angle of 5 degrees)

10. The optical filter according to claim 1, further satisfying the following spectral characteristic (i-22). (i-22) When the incident direction is from the second dielectric multilayer film side, in the wavelength range of 750 to 1000 nm, the minimum value of the absorption loss amounts defined below is 90% or more (Absorption loss amount) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectance at an incident angle of 5 degrees)

11. The optical filter according to claim 1, further satisfying the following spectral characteristic (i-23). When the incident direction is the side of the second dielectric multilayer film, in the spectral reflectance curve at an incident angle of 5 degrees, as the wavelength ranges from 750 nm to 1000 nm, the reflectance R2 at each wavelength at intervals of 1 nm ｎ（５ｄｅｇ） (n: any integer) is read, the reflectance R2 ｎ（５ｄｅｇ） is such that there are 200 or more values of n for which it is 1% or less

12. The optical filter according to claim 2, further satisfying the following spectral characteristic (i-24). When the incident direction is the side of the first dielectric multilayer film, in the spectroscopic reflectance curve at an incident angle of 5 degrees, as the wavelength ranges from 750 nm to 1000 nm, the reflectance R1 at each wavelength at intervals of 1 nm ｎ（５ｄｅｇ） (n: any integer) is read, the reflectance R1 ｎ（５ｄｅｇ） is such that there are 150 or more values of n for which it is 1% or less

13. The second dielectric multilayer film includes two or more of the H ２ layers, The above-mentioned H ２ Among the above-mentioned H layers, when the layer second closest to the phosphate glass is defined as the second H ２ layer, The first H ２ layer and the second H ２ layer, there is a second M layer composed of a single layer satisfying 1.2 ≤ QWOT ≤ 2.1 or a plurality of layers satisfying 1.2 ≤ total QWOT ≤ 2.1 ２ layer, The optical filter according to claim 1.

14. The second dielectric multilayer film is the first H ２ layer and the second M ２ layer, and a third M ２ layer that consists of a single layer satisfying 1.2 ≤ QWOT ≤ 2.1 or a plurality of layers whose total QWOT satisfies 1.2 ≤ QWOT ≤ 2.

1. The optical filter according to claim 13.

15. The first dielectric multilayer film includes two or more of the H １ layers, The above-mentioned H １ Among the layers, when the layer second closest to the resin film is defined as the second H １ layer, The first H １ layer and the second H １ layer, a second M layer comprising a single layer satisfying 1.2 ≤ QWOT ≤ 2.1 or a plurality of layers whose total QWOT satisfies 1.2 ≤ QWOT ≤ 2.1 １ The optical filter according to claim 2, including the layer

16. The first dielectric multilayer film has the first H １ layer and the second M １ layer, and includes a third M １ layer formed of a single layer satisfying 1.2 ≤ QWOT ≤ 2.1 or a plurality of layers satisfying 1.2 ≤ total QWOT ≤ 2.

1. The optical filter according to claim 15.

17. The optical filter according to claim 1 or 2, wherein the resin film has two or more near-infrared dyes.

18. The optical filter according to claim 1 or 2, having one or more layers of the resin film and another resin film.

19. The above phosphoric acid glass, in terms of mass percentage based on oxides, P ２ O ５ 40 to 80% Al ２ O ３ 0.5 to 20% ΣR ２ O (where R ２ O is Li ２ O, Na ２ O, K ２ O, Rb ２ O, and Cs ２ one or more components selected from, ΣR ２ O is the total amount of R ２ O) 0.5 to 20% ΣR'O (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR'O is the total amount of R'O) 0 to 40% CuO 0.5 to 40% The optical filter according to claim 1 or 2, having a composition containing the above.

20. The optical filter according to claim 1 or 2, wherein the thickness of the resin film is 10 μm or less.

21. An imaging device including the optical filter according to claim 1 or 2.

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