Optical filter

Abstract

The present invention aims to provide an optical filter that suppresses ripple and stray light in the visible light region and exhibits excellent transmittance in the visible light region and shielding in the near-infrared light region. [Solution] The present invention relates to an optical filter comprising, in this order, a first dielectric multilayer film, a resin film, a phosphoric acid glass containing 40% or more P2O5 by mass percentage on an oxide basis, and a second dielectric multilayer film, wherein the resin film comprises a resin and a near-infrared absorbing dye, and the second dielectric multilayer film comprises an H2 layer whose refractive index and QWOT are within a specific range, and when the H2 layer closest to the phosphoric acid glass is defined as the first H2 layer, a first M2 layer whose QWOT satisfies a specific range is included between the first H2 layer and the phosphoric acid glass, and the optical filter satisfies all predetermined spectral characteristics (i-1) to (i-2).

Description

[Technical Field]

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

[0002] In imaging devices using solid-state image sensors, optical filters are used that transmit visible light (hereinafter also referred to as "visible light") and block near-infrared wavelength light (hereinafter also referred to as "near-infrared light") in order to reproduce colors well and obtain sharp images.

[0003] Such optical filters can take various forms, such as reflective filters that alternately stack dielectric thin films with different refractive indices on one or both sides of a transparent substrate (dielectric multilayer film) and reflect the light to be blocked by utilizing light interference.

[0004] Patent documents 1 and 2 describe optical filters having a dielectric multilayer film and an absorbing 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 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Optical filters with dielectric multilayer films face the problem of changes in spectral transmittance and spectral reflectance curves depending on the angle of incidence, because the optical thickness of the dielectric multilayer film changes with the angle of incidence. For example, depending on the number of layers of the multilayer film, interference caused by reflected light at each layer interface causes a sharp change in transmittance in the visible light region, known as ripple, which tends to occur more strongly at larger angles of incidence. This results in a change in the amount of visible light captured at high angles of incidence, leading to a decrease in image reproducibility. In particular, with the recent trend towards lower-profile camera modules, use under high angle of incidence conditions is anticipated, so there is a need for optical filters that are less affected by the angle of incidence.

[0007] Furthermore, conventional optical filters that utilize the reflection of dielectric multilayer films can cause stray light, a phenomenon where light is generated outside the intended optical path, due to reflected light being re-reflected at the lens surface and incident, or light reflected at the sensor surface being re-reflected at the dielectric multilayer film surface and incident. Using such filters may cause flare and ghosting in solid-state image sensors, or lead to a decrease in image quality. In particular, with the recent increase in image quality of camera modules, there is a demand for optical filters that are less prone to generating stray light.

[0008] The present invention aims to provide an optical filter that suppresses ripple and stray light in the visible light region and exhibits excellent transmittance in the visible light region and shielding 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 a first dielectric multilayer film, a resin film, a phosphoric acid glass, and a second dielectric multilayer film in this order, The aforementioned resin film comprises a resin and a near-infrared absorbing dye. The aforementioned phosphate glass contains 40% or more P2O5 by mass percentage based on oxides. The first dielectric multilayer film and the second dielectric multilayer film include a plurality of layers with different refractive indices. The second dielectric multilayer film includes at least one H2 layer satisfying a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5. When the H2 layer closest to the phosphoric acid glass is designated as the first H2 layer, Between the first H2 layer and the phosphoric acid glass, there is a first M2 layer consisting of a single layer with a QWOT of 1.2 or more and 1.8 or less, or a plurality of layers with a total QWOT of 1.2 or more and 1.8 or less. The optical filter is an optical filter that 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 for wavelengths of 450-550 nm. 450-550(0deg)AVE over 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 450-550 nm 450-550(50deg)AVE over 85% [2] An optical filter comprising a first dielectric multilayer film, a resin film, a phosphoric acid glass, and a second dielectric multilayer film in this order, The aforementioned resin film comprises a resin and a near-infrared absorbing dye. The aforementioned phosphate glass contains 40% or more P2O5 by mass percentage based on oxides. The first dielectric multilayer film and the second dielectric multilayer film include a plurality of layers with different refractive indices. The first dielectric multilayer film includes at least one H1 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. When the H1 layer closest to the resin film is designated as the first H1 layer, Between the first H1 layer and the resin film, there is a first M1 layer consisting of a single layer whose QWOT is 1.2 or more and 1.8 or less, or a plurality of layers whose total QWOT is 1.2 or more and 1.8 or less. The optical filter is an optical filter that 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 for wavelengths of 450-550 nm. 450-550(0deg)AVE over 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 450-550 nm 450-550(50deg)AVE over 85% [Effects of the Invention]

[0010] According to the present invention, an optical filter can be provided that suppresses ripple and stray light in the visible light region and exhibits excellent transmittance in the visible light region and shielding in the near-infrared light region. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of an optical filter according to one embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing the configuration of the optical filter in Example 2-1. [Figure 3] Figure 3 is a schematic cross-sectional view showing the configuration of the optical filter in Example 2-2. [Figure 4] Figure 4 is a schematic cross-sectional view showing the configuration of the optical filter in Example 2-3. [Figure 5] Figure 5 shows the spectral transmittance curve of glass. [Figure 6] Figure 6 shows the spectral transmittance curve of the optical filter in Example 2-1. [Figure 7] Figure 7 shows the spectral reflectance curve of the optical filter in Example 2-1. [Figure 8] Figure 8 shows the spectral transmittance curve of the optical filter in Example 2-4. [Figure 9] Figure 9 shows the spectral reflectance curve of the optical filter in Example 2-4. [Figure 10] Figure 10 shows the spectral transmittance curve of the optical filter in Example 2-5. [Figure 11] Figure 11 shows the spectral reflectance curve of the optical filter in Example 2-5. [Figure 12] Figure 12 shows the spectral transmittance curve of the optical filter in Example 2-6. [Figure 13] Figure 13 shows the spectral reflectance curve of the optical filter in Example 2-6. [Modes for carrying out the invention]

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

[0013] In this specification, internal transmittance is defined as {measured transmittance (incident angle 0 degrees) / (100 - reflectance)}. This is the transmittance obtained by subtracting the effect of interfacial reflection from the measured transmittance, expressed by the formula (incident angle 5 degrees)) × 100. In this specification, the spectral transmission of a substrate and the transmission of a resin film, including cases where the dye is contained in the resin, are all referred to as "internal transmission" even when the term "transmission" is used. On the other hand, the transmission measured by dissolving the dye in a solvent such as dichloromethane, the transmission of a dielectric multilayer film, and the transmission of an optical filter having a dielectric multilayer film are measured transmissions.

[0014] In this specification, for a particular wavelength range, a transmittance of, for example, 90% or more means that the transmittance does not fall below 90% across the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, for a particular wavelength range, a transmittance of, for example, 1% or less means that the transmittance does not exceed 1% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance in a particular wavelength range are the arithmetic mean of the transmittance and internal transmittance for every 1 nm in that wavelength range. The spectral characteristics can be measured using a UV-Vis spectrophotometer. In this specification, the symbol "~" used to indicate a numerical range includes both upper and lower limits.

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

[0016] In this invention, at least one of the first dielectric multilayer film and the second dielectric multilayer film has low reflection characteristics even at high incidence angles, as described later, thus suppressing stray light. Furthermore, the light-shielding properties of the optical filter are substantially guaranteed by the absorption characteristics of the phosphate glass. Since the absorption characteristics are not affected by the angle of incidence of light, it is possible to suppress ripple in the visible light region while achieving excellent transmittance in the visible light region and excellent shielding in the near-infrared light region as a whole optical filter.

[0017] <Characteristics of optical filters> 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 for wavelengths of 450-550 nm. 450-550(0deg)AVE over 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 450-550 nm 450-550(50deg)AVE over 85% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 750 to 1000 nm. 750-1000(0deg)AVE less than 2.5% (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 750 to 1000 nm. 750-1000(50deg)AVE less than 2.5%

[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 shielding in the near-infrared region, as shown in characteristic (i-3). Furthermore, as shown in characteristics (i-2) and (i-4), the change in spectral characteristics is small at high incidence angles, and ripple in the visible light region is suppressed.

[0019] Satisfying the spectral characteristics (i-1) and (i-2) means excellent transmittance in the visible light region of 450 to 550 nm even at a high incident angle. 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 excellent transmittance in the near-infrared light region of 750 to 1000 nm even at a high incident angle. 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] The optical filter of the present invention preferably 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 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 (i-6) When the incident direction is the second dielectric multilayer film side, 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 (i-7) When the incident direction is the second dielectric multilayer film side, the average reflectance R2 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 (i-8) When the incident direction is the second dielectric multilayer film side, the average reflectance R2 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

[0022] Spectral characteristics (i-5) and (i-6) define the reflection characteristics of the second dielectric multilayer film, while spectral characteristics (i-7) and (i-8) define the reflection characteristics of the second dielectric multilayer film at high incidence angles. Even at high incidence angles, the low reflectivity in the visible and near-infrared regions suppresses reflection from the second dielectric multilayer film surface, which is a cause of stray light. Average reflectance R2 750-1000(5deg)AVE More preferably 1.5% or less, More preferably, it is 1% or less. Average reflectance R2 450-600(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less. Average reflectance R2 750-1000(50deg)AVE It is more preferably 3% or less, and even more preferably 2% or less. Average reflectance R2 450-600(50deg)AVE It is more preferably 4% or less, and even more preferably 3% or less.

[0023] The optical filter of the present invention preferably 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 for wavelengths of 1000 to 1200 nm. 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 for wavelengths of 1000 to 1200 nm. 1000-1200(50deg)AVE less than 7% (i-11) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 is such that the transmittance is 30%. (0deg) However, it is located at a wavelength of 630-680 nm. (i-12) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 is such that the transmittance is 30%. (50deg) However, it is located at a wavelength of 630-680 nm.

[0024] Satisfying spectral characteristics (i-9) and (i-10) means that the lens exhibits excellent light shielding in the near-infrared region of 1000-1200 nm, even at high incidence angles. Average transmittance T 1000-1200(0deg)AVEIt is more preferably 5% or less, and even more preferably 3% or less. Average transmittance T 1000-1200(50deg)AVE More preferably, 3% or less. More preferably, it is 2% or less.

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

[0026] The optical filter of the present invention preferably 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 for wavelengths of 750-1000 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 in the spectral reflectance curve at an incident angle of 5 degrees for wavelengths of 450-600 nm 450-600(5deg)AVE less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 for wavelengths of 750-1000 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 for wavelengths of 450-600 nm in the spectral reflectance curve at an incident angle of 50 degrees 450-600(50deg)AVE less than 5%

[0027] Spectral characteristics (i-13) and (i-14) define the reflection characteristics of the first dielectric multilayer film, while spectral characteristics (i-15) and (i-16) define the reflection characteristics of the first dielectric multilayer film at high incidence angles. Because the reflectivity is low even at high incidence angles, reflections from the dielectric multilayer film surface, which cause stray light, can be suppressed. Average reflectance R1 750-1000(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less. Average reflectance R1 450-600(5deg)AVE More preferably, 1.5% or less. More preferably, it is 1% or less. Average reflectance R1 750-1000(50deg)AVE It is more preferably 3.5% or less, and even more preferably 2% or less. Average reflectance R1 450-600(50deg)AVE It is more preferably 4% or less, and even more preferably 3.5% or less.

[0028] The optical filter of the present invention preferably 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 spectral characteristics (i-17) to (i-19) means that the transmittance in the visible light region of 450-600 nm and the near-infrared light region of 750-1200 nm does not change significantly even at high incidence angles, i.e., ripple is suppressed. The absolute value of the spectral characteristic (i-17) is more preferably 3.2% or less, and even more preferably 3% or less. The absolute value of the spectral characteristic (i-18) is more preferably 1% or less, and even more preferably 0.5% or less. The absolute value of the spectral characteristic (i-19) is more preferably 1.3% or less, and even more preferably 1.2% or less.

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

[0031] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-21). (i-21) When the second dielectric multilayer film side is the incident direction, the average of the 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)

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

[0033] The optical filter of the present invention preferably further satisfies the following spectral characteristics (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 characteristics (i-22) means that both transmittance in the visible light region and shielding in the near-infrared light region are achieved. The minimum absorption loss is more preferably 92% or higher, and even more preferably 94% or higher.

[0035] The optical filter of the present invention preferably further satisfies the following spectral characteristics (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 of each wavelength is shown at intervals of 1 nm from wavelength 750 nm to wavelength 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R2 n(5deg) However, there are more than 200 values ​​of n for which the percentage is less than 1%.

[0036] The spectral characteristics (i-23) define the reflection characteristics on the second dielectric multilayer film side, and a low reflectivity means that reflection at the dielectric multilayer film surface, which causes stray light, can be suppressed. Reflectance R2 n(5deg) For n to be 1% or less, it is more preferably 220 or more, and even more preferably 230 or more.

[0037] The optical filter of the present invention preferably further satisfies the following spectral characteristics (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 of each wavelength is shown at intervals of 1 nm from wavelength 750 nm to wavelength 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R1 n(5deg) However, there are more than 150 values ​​of n for which the percentage is less than 1%.

[0038] The spectral characteristics (i-24) define the reflection characteristics on the first dielectric multilayer film side, and a low reflectivity means that reflection at the dielectric multilayer film surface, which causes stray light, can be suppressed. Reflectance R1 n(5deg) For n to be 1% or less, it is more preferably 180 or more, and even more preferably 200 or more.

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

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

[0041] Minimum transmittance T 450-550(0deg)MIN It is more preferably 85% or more, and even more preferably 87% or more. Maximum transmittance T 450-550(0deg)MAX It is more preferably 92% or more, and even more preferably 94% or more. Maximum transmittance T 750-1000(0deg)MAX It is more preferably 1% or less, and even more preferably 0.9% or less. Maximum transmittance T 1000-1200(0deg)MAX More preferably, it is 5% or less, and even more 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 high incidence angles. In the present invention, because the second dielectric multilayer film suppresses reflection in the visible light region and the near-infrared light region, ripple generation in the visible light region is reduced, and an optical filter is obtained in which stray light is suppressed because the spectral characteristics do not change easily with respect to light at high incidence angles.

[0043] The second dielectric multilayer film is a multilayer film that contains multiple layers with different refractive indices, and these layers are stacked alternately. More specifically, it includes a dielectric layer with a low refractive index (low refractive index layer), a dielectric layer with a medium refractive index (medium refractive index layer), and a dielectric layer with a high refractive index (high refractive index layer), and two or more of these dielectric layers are stacked alternately in this multilayer film.

[0044] The high refractive index layer preferably has a refractive index of 1.6 or higher at a wavelength of 500 nm, more preferably 2.2 to 2.5. Examples of materials for the high refractive index layer include Ta2O5 and TiO2. Examples include 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. Of these, TiO2 is preferred in terms of film formation properties, reproducibility in refractive index, and stability.

[0045] The intermediate 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 intermediate refractive index layer include ZrO2, Nb2O5, Al2O3, HfO2, OM-4 and OM-6 (a mixture of Al2O3 and ZrO2) sold by Canon Optron, OA-100, and H4 and M2 (alumina antania) sold by Merck. Of these, Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred in terms of film formation 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, and more preferably 1.38 to 1.5. Examples of materials for the low refractive index layer include SiO2 and SiO2. x N y、 Examples include MgF2. Other commercially available products include S4F and S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron. Of these, SiO2 is preferred in terms of reproducibility, stability, and cost-effectiveness in film formation.

[0047] (Configuration of the second dielectric multilayer film) Figure 2 is a schematic cross-sectional view showing the configuration of the optical filter fabricated in Example 2-1, which will be described later. In Example 2-1, the second dielectric multilayer film 20A had a laminated structure in which TiO2 (refractive index at 500 nm: 2.467) as a high refractive index layer and SiO2 (refractive index at 500 nm: 1.483) as a low refractive index layer were alternately stacked. However, this embodiment is not limited to this configuration. You can choose any of the above materials.

[0048] As shown in Figure 2, the second dielectric multilayer film includes at least one H2 layer satisfying the following conditions: a refractive index at 500 nm is between 1.8 and 2.5, and a QWOT (Quarter Wave Optical Thickness) is between 1.1 and 3.5. The refractive index of the H2 layer is Preferably, it is 1.9 to 2.5, more preferably 2.0 to 2.5, and even more preferably 2.1 to 2.5.

[0049] Here, QWOT can be calculated using the following formula. QWOT = (Physical film thickness / Center wavelength) × 4 × Refractive index Note that 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 Figure 2, the second dielectric multilayer film includes a first M2 layer between the first H2 layer and the phosphoric acid glass, where the H2 layer closest to the phosphoric acid glass is designated as the first H2 layer, and the sum of the QWOTs of each layer satisfies the condition that the sum of the QWOTs of each layer is between 1.2 and 1.8. In the example shown in Figure 2, the layer closest to the phosphate glass is designated as the first layer, and the first M2 layer is composed of four layers, from the first to the fourth layer. However, the first M2 layer may consist of any number of layers as long as the sum of the QWOT of each layer is between 1.2 and 1.8. In other words, the first M2 layer may be a single layer satisfying a QWOT of 1.2 or more and 1.8 or less. However, from the viewpoint of improving productivity, the first M2 layer is preferably composed of six layers or less. It is more preferable to have three layers or fewer.

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

[0052] More specifically, the following characteristics are obtained when the second dielectric multilayer film has the above configuration. (i-5) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 for wavelengths of 750-1000 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 in the spectral reflectance curve at an incident angle of 5 degrees for wavelengths of 450-600 nm. 450-600(5deg)AVE less than 3% (i-7) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 for wavelengths 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 for wavelengths of 450-600 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 can be placed at any position between the first H2 layer and the phosphate glass. Specifically, in Figure 2, the first M2 layer is composed of all the layers (layers 1 to 4) contained between the phosphate glass and the first H2 layer, but the first M2 layer consists of the layer closest to the phosphate glass (layer 1) up to the third layer (layer 3) (in this case, The sum of the QWOT of the first to third layers is 1.423), and the SiO2 layer (fourth layer), which is the layer closest to the first H2 layer, may be any layer.

[0054] Furthermore, if there are multiple single layers between the first H2 layer and the phosphate glass that satisfy a QWOT of 1.2 or more and 1.8 or multiple consecutive layers that satisfy a total QWOT of 1.2 or more and 1.8 or less, any one of the single layers or multiple consecutive layers shall be designated as the first M2 layer, and the other layers shall be designated as arbitrary layers.

[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, any layer may be included between the first H2 layer and the phosphate glass, to the extent that it does not hinder the effects of the present invention. 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 there is no arbitrary layer between the first H2 layer and the phosphate glass. That is, it is preferable that the first H2 layer, the first M2 layer and the phosphate glass are formed continuously.

[0056] Examples of materials for any given layer include the high refractive index layer, medium refractive index layer, and low refractive index layer mentioned above.

[0057] Furthermore, the second dielectric multilayer film may have a configuration that includes two or more H2 layers, as shown in Figure 3. In this case, as shown in Figure 3, when the second H2 layer is the layer second closest to the phosphoric acid glass, it is preferable to include a second M2 layer between the first H2 layer and the second H2 layer, which consists of a plurality of continuous layers such that the sum of the QWOTs of each layer is between 1.2 and 2.1. By including a second M2 layer between the first H2 layer and the second H2 layer, the second M2 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smoother, so that reflection is further suppressed over a wide wavelength range from the visible light region to the near-infrared light region.

[0058] In the example shown in Figure 3, the second M2 layer consists of three layers, from the 6th to the 8th layer. However, the second M2 layer can consist of any number of layers as long as the sum of the QWOT of each layer is between 1.2 and 2.1. In other words, the second M2 layer may be a single layer satisfying the QWOT of 1.2 or more and 2.1 or less. 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 Figure 4, it is preferable to include two single layers or multiple consecutive layers between the first H2 layer and the second H2 layer, where the QWOT is 1.2 or more and 2.1 or less. In this case, as shown in Figure 4, among the corresponding single layers or multiple consecutive layers, the layer closest to the second H2 layer is designated as the second M2 layer, and the layer second closest to the second H2 layer is designated as the third M2 layer. That is, in addition to the second M2 layer, it is preferable that the second dielectric multilayer film includes a third M2 layer between the first H2 layer and the second M2 layer, consisting of a single layer or multiple layers where the QWOT is 1.2 or more and 2.1 or less, or where the total QWOT is 1.2 or more and 2.1 or less.

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

[0061] As mentioned above, the second and third M2 layers can be placed at any position as long as the layer closest to the second H2 layer is the second M2 layer.

[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 that satisfy a QWOT of 1.2 or more and 2.1 or less, or consecutive layers whose total QWOT is 1.2 or more and 2.1 or less. However, there may be three or more such single layers or consecutive layers.

[0063] Furthermore, any layer other than the second M2 layer and the third M2 layer may be included between the first H2 layer and the second H2 layer, as long as it does not hinder the effects of the present invention. Examples of such arbitrary layers are the same as those described above. However, from the viewpoint of improving productivity, it is preferable that no arbitrary 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 in a continuous manner. Furthermore, even if there is no third M2 layer, it is preferable that no other layers exist, and that the second H2 layer, the second M2 layer, and the first H2 layer are formed in a continuous manner.

[0064] Furthermore, from the viewpoint of further suppressing reflection, it is preferable that the QWOT values ​​of the first H2 layer and the second H2 layer in the second dielectric multilayer film are different. Also, from the same viewpoint, it is preferable that the sum of the QWOT values ​​of the single layers or the QWOT values ​​of the multiple consecutive layers constituting the first M2 layer, the second M2 layer, and the third M2 layer are different.

[0065] Furthermore, the total number of dielectric layers in the second dielectric multilayer film is preferably 10 to 30 layers. 10 to 20 layers are more preferable. Keeping the total number of layers within the above range prevents an increase in the film thickness per layer.

[0066] Furthermore, the overall thickness of the second dielectric multilayer film is preferably 0.5 to 2.0 μm, and more preferably 0.5 to 1.0 μm. Keeping the thickness of the second dielectric multilayer film within the above range prevents an increase in the thickness of each individual layer.

[0067] The formation of the second dielectric multilayer film and the first dielectric multilayer film, described later, can be carried out using, for example, vacuum deposition processes such as CVD, sputtering, and vacuum evaporation, or wet deposition processes such as spraying and dipping.

[0068] <First Dielectric Multilayer Film> In this filter, it is preferable that the first dielectric multilayer film 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, the generation of ripple in the visible light region is reduced, and furthermore, the spectral characteristics do not change easily with light at high incident angles, resulting in an optical filter with suppressed stray light.

[0069] The first dielectric multilayer film is a multilayer film containing multiple layers with different refractive indices, in which these layers are stacked alternately. More specifically, it may include a dielectric layer with a low refractive index (low refractive index layer), a dielectric layer with a medium refractive index (medium refractive index layer), and a dielectric layer with a high refractive index (high refractive index layer), and it is a multilayer film in which two or more of these dielectric layers are stacked alternately.

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

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

[0072] When the first dielectric multilayer film is defined as the first H1 layer, with the H1 layer closest to the resin film being designated as the first H1 layer, as shown in Figure 2, it is preferable that the first M1 layer, consisting of a plurality of continuous layers, is included between the first H1 layer and the resin film, such that the sum of the QWOT of each layer is 1.2 or more and 1.8 or less.

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

[0074] More specifically, the following characteristics are obtained when the first dielectric multilayer film has the above configuration. (i-13) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 for wavelengths of 750-1000 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 in the spectral reflectance curve at an incident angle of 5 degrees for wavelengths of 450-600 nm 450-600(5deg)AVE less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 for wavelengths of 750-1000 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 for wavelengths of 450-600 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 can be positioned at any location between the first H1 layer and the resin film. Specifically, in Figure 2, the first M1 layer is composed of all the layers (layers 1 to 4) contained between the resin film and the first H1 layer. However, the first M1 layer may consist of the layer closest to the resin film (layer 1) up to the third layer (layer 3) (in this case, the sum of the QWOT of layers 1 to 3 is 1.423), and the SiO2 layer (layer 4), which is closest to the first H1 layer, may be any other layer.

[0076] Furthermore, if there are multiple single layers between the first H1 layer and the resin film, where QWOT is between 1.2 and 1.8, or multiple consecutive layers where the sum of QWOT is between 1.2 and 1.8, then any one of the single layers or multiple consecutive layers shall be designated as the first M1 layer, and the other layers shall be designated as arbitrary layers.

[0077] Thus, any layer may be included between the first H1 layer and the resin layer, as long as it does not hinder the effects of the present invention. For example, the arbitrary layer may be included between the resin layer and the first M1 layer, or between the first M1 layer and the first H1 layer. Examples of arbitrary layers are the same as those described above.

[0078] Furthermore, as shown in Figure 3, the first dielectric multilayer film may have a configuration that includes two or more H1 layers. In this case, when the layer second closest to the resin film is designated as the second H1 layer, it is preferable to include a second M1 layer between the first H1 layer and the second H1 layer, which consists of a series of consecutive layers satisfying a total QWOT of 1.2 or more and 2.1 or less. Between the first H2 layer and the second H2 layer, The presence of a second M1 layer allows the second M1 layer to function as an intermediate refractive index layer, resulting in a smoother spectral waveform, which further suppresses reflection when incident from the resin surface of the optical filter.

[0079] Furthermore, the second M1 layer may consist of any number of layers, as long as the sum of the QWOT of each layer is between 1.2 and 2.1. In other words, the second M1 layer may be a single layer satisfying 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 Figure 4, it is preferable to include two single layers or multiple consecutive layers between the first H1 layer that satisfy a QWOT of 1.2 or more and 2.1 or less, respectively, where the total QWOT is 1.2 or more and 2.1 or less. In this case, among the single layers or multiple consecutive layers, the layer closest to the second H1 layer is designated as the second M1 layer, and the layer second closest to the second H1 layer is designated as the third M1 layer. That is, in addition to the second M1 layer, the first dielectric multilayer film preferably includes a third M1 layer between the first H1 layer and the second M1 layer, consisting of a single layer or multiple layers that satisfy a QWOT of 1.2 or more and 2.1 or less, respectively, where the total QWOT is 1.2 or more and 2.1 or less.

[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 and further suppressing reflection over a wide wavelength range from the visible light region to the near-infrared light region.

[0082] As mentioned above, the second and third M1 layers can be placed at any position as long as the layer closest to the second H1 layer is the second M1 layer.

[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 that satisfy a QWOT of 1.2 or more and 2.1 or less, or a total of multiple layers (the second M1 layer and the third M1 layer) that satisfy a QWOT of 1.2 or more and 2.1 or less. However, there may be three or more such single layers or multiple layers.

[0084] Furthermore, any layer other than the second M1 layer and the third M1 layer may be included between the first H1 layer and the second H1 layer, as long as it does not hinder the effects of the present invention. Examples of such arbitrary layers are the same as those described above. However, from the viewpoint of improving productivity, it is preferable that no arbitrary 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 in a continuous manner. Furthermore, even if there is no third M1 layer, it is preferable that no other layers exist and that the second H1 layer, the second M1 layer, and the first H1 layer are formed in a continuous manner.

[0085] Furthermore, from the viewpoint of further suppressing reflection, it is preferable that the QWOT values ​​of the first H1 layer and the second H1 layer in the first dielectric multilayer film are different. Also, from the same viewpoint, it is preferable that the QWOT values ​​of the single layers or the sum of the QWOT values ​​of the multiple consecutive layers constituting the first M1 layer, the second M1 layer, and the third M1 layer are different.

[0086] Furthermore, the total number of dielectric layers in the first dielectric multilayer film is preferably 10 to 30 layers. 10 to 20 layers are more preferable. Keeping the total number of layers within the above range prevents an increase in the film thickness per layer.

[0087] Furthermore, the overall 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> The phosphate glass preferably satisfies all of the following spectral characteristics (ii-1) to (ii-3). (ii-1) Internal transmittance T at a wavelength of 450 nm 450 over 92% (ii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE over 90% (ii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 625-650 nm. (ii-4) Average internal transmittance T at wavelength 750~1000nm 750-1000AVE less than 2.5% (ii-5) Average internal transmittance T at wavelength 1000~1200nm 1000-1200AVE less than 7%

[0089] Meeting spectral characteristic (ii-1) means excellent transmittance in the blue light region, and meeting spectral characteristic (ii-2) means superior transmittance in the visible light region from 450 to 600 nm. Internal transmittance T 450 It is more preferably 93% or more, and even more preferably 95% or more. Average internal transmittance T 450-600AVE It is more preferably 94% or more, and even more preferably 95% or more.

[0090] By satisfying the spectral characteristics (ii-3), it means that light in the near-infrared region can be blocked and visible transmitted light can be efficiently captured. The wavelength IR50 is more preferably in the range of 625 to 645 nm, and even more preferably in the range of 625 to 640 nm.

[0091] Satisfying spectral characteristics (ii-4) means that the material exhibits excellent light-shielding properties in the near-infrared region of 750-1000 nm. T 750-1000AVE It is more preferably 2% or less, and even more preferably 1.2% or less.

[0092] Meeting the spectral characteristics (ii-5) means that it has excellent light-shielding properties in the near-infrared region of 1000-1200 nm. Average internal transmittance T 1000-1200AVE It is more preferably 6.8% or less, and even more preferably 6.5% or less.

[0093] In the present invention, it is preferable that the phosphate glass exhibits near-infrared light absorption starting in the 625-650 nm region, as shown in characteristic (ii-3) above, and high light-shielding properties from 750 nm onward, as shown in characteristic (ii-4) above. This provides a substrate that can compensate for the light-shielding properties of the dielectric multilayer film described above.

[0094] In this invention, phosphate glass refers to glass containing 40% or more P2O5 by mass percentage based on oxides. Furthermore, it is preferable that the phosphate glass contains copper ions. The inclusion of copper ions, which absorb light around 900 nm, allows for the blocking of near-infrared light in the 700-1200 nm range. Note that phosphate glass also includes silicate glass, in which part of the glass framework is composed of SiO2.

[0095] For example, it is preferable that the phosphated glass contains the following components that make up the glass. The percentages of each glass component listed below are expressed as mass percentages based on oxides. P2O 540-80% Al2O3 0.5-20% ΣR2O (where 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 (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) 0~40%CuO 0.5~40%

[0096] P2O5 is the main component that forms glass and is an ingredient that enhances near-infrared ray blocking properties. If the P2O5 content is 40% or more, the effect is sufficiently obtained, and if it is 80% or less, problems such as glass instability and reduced weather resistance are less likely to occur. For this reason, it is preferably 40-80%, more preferably 45-78%, even more preferably 50-77%, even more preferably 55-76%, and most preferably 60-75%.

[0097] Al2O3 is the main component that forms glass and is used to increase the strength and weather resistance of glass. If the Al2O3 content is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, problems such as glass instability and reduced near-infrared ray blocking are less likely to occur. For this reason, it 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 (where R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. If the total amount of R2O (ΣR2O) is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, it is preferable because the glass is less likely to become unstable. 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 that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. The Li2O content is preferably 0 to 15%. A Li2O content of 15% or less is preferable because it is less likely to cause problems such as glass instability or a decrease in near-infrared cut performance. 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 that lowers the melting temperature of glass, lowers the liquidus temperature of glass, and stabilizes glass. The Na2O content is preferably 0 to 15%. A Na2O content of 15% or less is preferable because it makes the glass less unstable. More preferably 0.5 to 14%, even more preferably 1 to 13%, even more preferably 2 to 13%, and most preferably 3 to 13%.

[0101] K2O is a component that has effects such as lowering the melting temperature of glass and lowering the liquidus temperature of glass. The K2O content is preferably 0 to 20%. A K2O content of 20% or less is preferable because it makes the glass less unstable. More preferably 0.5 to 19%, even more preferably 1 to 18%, even more preferably 2 to 17%, and most preferably 3 to 16%.

[0102] Rb2O is a component that has effects such as lowering the melting temperature of glass and lowering the liquidus temperature of glass. The Rb2O content is preferably 0 to 15%. An Rb2O content of 15% or less is preferable because it makes the glass less unstable. More preferably 0.5 to 14%, even more preferably 1 to 13%, even more preferably 2 to 13%, and most preferably 3 to 13%.

[0103] Cs2O is a component that has effects such as lowering the melting temperature of glass and lowering the liquidus temperature of glass. The Cs2O content is preferably 0 to 15%. A Cs2O content of 15% or less is preferable because it makes the glass less unstable. More preferably 0.5 to 14%, even more preferably 1 to 13%, even more preferably 2 to 13%, and most preferably 3 to 13%.

[0104] Furthermore, the alkali metal components shown as R2O above produce a mixed alkali effect in the glass when two or more of each component are added simultaneously, R + The mobility of ions decreases. As a result, when glass comes into contact with water, the H in the water molecules+ Ions and R in glass + This inhibits the hydration reaction caused by ion exchange, thereby improving the weather resistance of the glass. Therefore, the phosphate glass of this embodiment preferably contains two or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O. In this case, R2O (where R2O is Li2O, The total amount of Na2O, K2O, Rb2O, and Cs2O (ΣR2O) is preferably more than 7% and 18% or less. 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, reduced near-infrared cutting performance, and reduced glass strength are less likely to occur, which is preferable. For this reason, ΣR2O is preferably more than 7% and 18% or less, 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 (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and increases the strength of the glass. The total amount of R'O (ΣR'O) is preferably 0 to 40%. A total amount of R'O of 40% or less is preferable because it is less likely to cause problems such as glass instability, reduced near-infrared cut properties, and reduced strength of the glass. More preferably it is 0 to 35%, and even more preferably 0 to 30%. More preferably, it is 0-25%, particularly preferably 0-20%, and most preferably 0-15%.

[0106] CaO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. A CaO content of 0 to 10% is preferred. A CaO content of 10% or less is preferred because it is less likely to cause problems such as glass instability or a decrease in near-infrared ray blocking properties. More preferably, it is 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 that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The MgO content is preferably 0 to 15%. An MgO content of 15% or less is preferable because it is less likely to cause problems such as glass instability or a decrease in near-infrared ray blocking properties. More preferably 0 to 13%, even more preferably 0 to 10%, even more preferably 0 to 9%, and most preferably 0 to 8%.

[0108] BaO is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. The BaO content is preferably 0 to 40%. A BaO content of 40% or less is preferable because it is less likely to cause problems such as glass instability or a decrease in near-infrared ray blocking properties. More preferably 0 to 30%, even more preferably 0 to 20%, even more preferably 0 to 10%, and most preferably 0 to 5%.

[0109] SrO is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. The SrO content is preferably 0 to 10%. A SrO content of 10% or less is preferable because it is less likely to cause problems such as glass instability or a decrease in near-infrared ray blocking properties. More preferably 0 to 8%, even more preferably 0 to 7%, and most preferably 0 to 6%.

[0110] ZnO has effects such as lowering the melting temperature of glass and lowering the liquidus temperature of glass. A ZnO content of 0-15% is preferable. If the ZnO content is 15% or less, This is preferable because it is less likely to cause problems such as glass becoming unstable, glass solubility deteriorating, and near-infrared cut performance decreasing. More preferably 0-13%, even more preferably 0-10%, even more preferably 0-9%, and most preferably 0-8%.

[0111] CuO is an ingredient that enhances near-infrared ray blocking. The CuO content is preferably 0.5 to 40%. A CuO content of 0.5% or more is sufficient to obtain the desired effect, while a content of 40% or less is preferable because it is less likely to cause problems such as the formation of devitrified foreign matter in the glass or a decrease in the transmittance of visible light. More preferably, it is 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 phosphoric acid glass according to this embodiment, F may be included in a range of 10% or less to improve weather resistance. A F content of 10% or less is preferable because it is less likely to cause problems such as a decrease in near-infrared cut performance and the occurrence of devitrified foreign matter in the glass. More preferably, it is 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 included in an amount of 10% or less to stabilize the glass. A B2O3 content of 10% or less is preferable because it is less likely to cause problems such as deterioration of the glass's weather resistance or reduction of near-infrared ray blocking properties. More preferably, it is 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 are used. These components may be included in amounts of 5% or less to improve the weather resistance of the phosphate glass. It is preferable that the content of these components is 5% or less because problems such as the formation of devitrified foreign matter in the glass and a decrease in near-infrared ray blocking properties are less likely to occur. Preferably, it is 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 of these components, when present in phosphate glass, reduce the transmittance of visible light. Therefore, it is preferable that these components are not substantially included in the glass. In this invention, "substantially free of specific components" means that they are not intentionally added, and does not mean that they are excluded from being inevitably mixed in from raw materials, etc., to an extent that does not affect the intended 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 preferably 0.1 mm or more, more preferably 0.15 mm or more, from the viewpoint of maintaining element strength.

[0117] Phosphate glass can be prepared, for example, as follows: First, the raw materials are weighed and mixed to achieve the above composition range (mixing step). This raw material mixture is placed in a platinum crucible and heated and melted in an electric furnace at a temperature of 700 to 1400°C (melting step). After thorough stirring and clarification, it is cast into a mold, cut and polished to form a flat plate of the specified thickness (forming step).

[0118] In the melting step of the above manufacturing method, it is preferable to keep the highest temperature of the glass during melting below 1400°C. If the highest temperature of the glass during melting exceeds this temperature, the transmittance characteristics may deteriorate. The above temperature is more preferably 1350°C or lower, even more preferably 1300°C or lower, and even more preferably 1250°C or lower. Furthermore, if the temperature in the above dissolution process is too low, problems such as devitrification during dissolution and a long time for complete dissolution may occur. Therefore, the temperature is preferably 700°C or higher, and more preferably 800°C or higher.

[0119] <Resin film> The resin film in the optical filter of the present invention comprises a resin and a near-infrared absorbing dye having a maximum absorption wavelength of 690 to 800 nm in the resin. Here, "resin" refers to the resin constituting the resin film.

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

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

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

[0123] By satisfying the spectral characteristics (iii-3), when used in combination with the phosphate glass described above, an optical filter can be obtained in which the incident angle dependence 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 even more preferably in the range of 665 to 685 nm.

[0124] The resin film in this invention contains a dye having a maximum absorption wavelength in the 690-800 nm range, which allows for light shielding in the near-infrared region around 700 nm, where phosphate glass has somewhat weak light-shielding properties, due to the absorption characteristics of the dye.

[0125] Examples of near-infrared absorbing dyes include at least one selected from the group consisting of cyanine dyes, phthalocyanine dyes, squarylium dyes, naphthalocyanine dyes, and diimonium dyes, which can be used individually or in combination. Among these, squarylium dyes and cyanine dyes are preferred from the viewpoint of easily exhibiting 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, per 100 parts by mass of resin. When two or more compounds are combined, the above content is the sum of the individual compounds.

[0127] The resin film may contain other dyes, such as ultraviolet light absorbing dyes, as long as they do not impair the effects of the present invention. 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. One type may be used alone, or two or more types may be used in combination.

[0128] The resin is not limited to transparent resins, 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, poly-paraphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin can be used. These resins may be used individually or in mixtures of two or more. From the viewpoint of the spectral properties of the resin film, glass transition temperature (Tg), and adhesion, one or more resins selected from polyimide resin, polycarbonate resin, polyester resin, and acrylic resin are preferred.

[0129] When multiple dyes are used, they may be contained in the same resin film, or they may each be contained in separate resin films.

[0130] The resin film can be formed by preparing a coating solution by dissolving or dispersing a dye, a resin or resin raw material component, and other components as needed in a solvent, coating this solution onto a support, drying it, and further curing it as needed. The support in this case may be the phosphate glass used in this filter, or a release-type support used only when forming the resin film. Furthermore, The solvent can be any dispersion medium that can stably disperse the substance or any solvent that can dissolve the substance.

[0131] Furthermore, the coating solution may contain a surfactant to improve voids caused by minute bubbles, indentations caused by the adhesion of foreign matter, and repulsion during the drying process. In addition, methods such as immersion coating, cast coating, or spin coating can be used for applying the coating solution. After applying the above coating solution to the support, a resin film is formed by drying. Furthermore, if the coating solution contains raw material components of a transparent resin, a curing treatment such as thermosetting or photocuring is performed.

[0132] Furthermore, the resin film can also be manufactured in film form by extrusion molding. The resulting film-like resin film can be laminated onto phosphate glass and integrated by thermocompression bonding or the like to produce a substrate.

[0133] The resin film may be present as one layer within the optical filter, or as two or more layers. If there are two or more layers, each layer may have the same or different configuration.

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

[0135] <Other> This filter may also include other components, such as a component (layer) that provides absorption by inorganic nanoparticles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic nanoparticles include ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, and lanthanum boride. ITO nanoparticles and cesium tungstate nanoparticles have high transmittance of visible light and light absorption over a wide range in the infrared wavelength region exceeding 1200 nm, and can therefore be used when shielding against such infrared light is required.

[0136] As described above, the following optical filters and the like are disclosed in this specification. [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, The resin film comprises a resin and a dye having a maximum absorption wavelength of 690 to 800 nm in the resin. The first dielectric multilayer film and the second dielectric multilayer film include a plurality of layers with different refractive indices. The second dielectric multilayer film includes at least one H2 layer satisfying a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5. When the H2 layer closest to the phosphoric acid glass is designated as the first H2 layer, Between the first H2 layer and the phosphoric acid glass, there is a first M2 layer consisting of a single layer with a QWOT of 1.2 or more and 1.8 or less, or a plurality of layers with a total QWOT of 1.2 or more and 1.8 or less. The optical filter is an optical filter that 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 for wavelengths of 450-550 nm. 450-550(0deg)AVE over 85% (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 450-550 nm 450-550(50deg)AVE over 85% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 750 to 1000 nm. 750-1000(0deg)AVE less than 2.5% (i-4) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T for wavelengths of 750 to 1000 nm. 750-1000(50deg)AVE less than 2.5% [2] An optical filter comprising a first dielectric multilayer film, a resin film, a phosphoric acid glass, and a second dielectric multilayer film in this order, The resin film comprises a resin and a dye having a maximum absorption wavelength of 690 to 800 nm in the resin. The first dielectric multilayer film and the second dielectric multilayer film include a plurality of layers with different refractive indices. The first dielectric multilayer film includes at least one H1 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. When the H1 layer closest to the resin film is designated as the first H1 layer, Between the first H1 layer and the resin film, there is a first M1 layer consisting of a single layer whose QWOT is 1.2 or more and 1.8 or less, or a plurality of layers whose total QWOT is 1.2 or more and 1.8 or less. An optical filter that 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 at wavelengths of 450 to 550 nm 450-550(0deg)AVE is 85% or more (i-2) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T at wavelengths of 450 to 550 nm 450-550(50deg)AVE is 85% or more (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T at wavelengths of 750 to 1000 nm 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 at wavelengths of 750 to 1000 nm 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 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 (i-6) When the second dielectric multilayer film side is the incident direction, 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 (i-7) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 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 (i-8) When the second dielectric multilayer film side is the incident direction, the average reflectance R2 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 [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 at wavelengths of 1000 to 1200 nm 1000-1200(0deg)AVE is 7% or less (i-10) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T at wavelengths of 1000 to 1200 nm 1000-1200(50deg)AVEless than 7% (i-11) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR30 is such that the transmittance is 30%. (0deg) However, it is located at a wavelength of 630-680 nm. (i-12) In the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 is such that the transmittance is 30%. (50deg) However, it is located at a wavelength of 630-680 nm. [5] 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 H1 layer closest to the resin film is designated as the first H1 layer, The optical filter according to any one of [1], [3], or [4], characterized in that it includes a first M1 layer between the first H1 layer and the resin film, the first M1 layer consisting of a single layer with a QWOT of 1.2 or more and 1.8 or less, or a plurality of layers with a total QWOT of 1.2 or more and 1.8 or less. [6] 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 H2 layer closest to the phosphoric acid glass is designated as the 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 phosphoric acid glass, the first M2 layer consisting of a single layer having a QWOT of 1.2 or more and 1.8 or less, or a plurality of layers having a total QWOT of 1.2 or more and 1.8 or less. [7] The optical filter described in [5], which 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 of the spectral reflectance curve at an incident angle of 5 degrees for wavelengths of 750 to 1000 nm 750-1000(5deg)AVE less than 3% (i-14) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 in the spectral reflectance curve at an incident angle of 5 degrees for wavelengths of 450 to 600 nm 450-600(5deg)AVE less than 3% (i-15) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 of the spectral reflectance curve at an incident angle of 50 degrees for wavelengths of 750 to 1000 nm 750-1000(50deg)AVE less than 5% (i-16) When the first dielectric multilayer film side is the incident direction, the average reflectance R1 in the spectral reflectance curve at an incident angle of 50 degrees for wavelengths of 450 to 600 nm 450-600(50deg)AVE less than 5% [8] An optical filter according to any one of [1] to [7], which further satisfies 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 for wavelengths 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 for wavelengths of 1000-1200 nm 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 is such that the transmittance is 30%. (0deg) And, in the spectral transmittance curve at an incident angle of 50 degrees, the wavelength IR30 has a transmittance of 30%. (50deg) The absolute value of the difference is 15 nm or less. [9] An optical filter according to any one of [1] to [8], which further satisfies the following spectral characteristics (i-21). (i-21) When the second dielectric multilayer film side is the incident direction, the average of the 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] An optical filter according to any one of [1] to [9], which further satisfies the following spectral characteristics (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 defined below is 90% or more. (Absorption loss) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees)

[11] An optical filter described in any one of [1] to

[10] , which further satisfies the following spectral characteristics (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 of each wavelength is shown at intervals of 1 nm from wavelength 750 nm to wavelength 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R2 n(5deg) However, there are more than 200 values ​​of n for which the percentage is less than 1%.

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

[11] , which further satisfies the following spectral characteristics (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 of each wavelength is shown at intervals of 1 nm from wavelength 750 nm to wavelength 1000 nm. n(5deg) When (n: any integer) is read, the reflectance R1 n(5deg) However, there are more than 150 values ​​of n for which the percentage is less than 1%.

[13] The second dielectric multilayer film comprises two or more H2 layers, When the H2 layer closest to the phosphoric acid glass is designated as the second H2 layer, An optical filter according to any one of [1], [3] to [5], [7] to

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

[14] The optical filter according to

[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 consisting of a single layer or multiple layers whose QWOT is 1.2 or more and 2.1 or less, and whose total QWOT is 1.2 or more and 2.1 or less.

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

[14] , wherein the phosphoric acid 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 over 92% (ii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE over 90% (ii-3) The wavelength IR50 at which the internal transmittance is 50% is in the range of 625-650 nm. (ii-4) Average internal transmittance T at wavelength 750~1000nm 750-1000AVE less than 2.5% (ii-5) Average internal transmittance T at wavelength 1000~1200nm 1000-1200AVE less than 7%

[16] The resin film satisfies all of the following spectral characteristics (iii-1) to (iii-3): An optical filter as described in any one of [1] to

[15] . (iii-1) Internal transmittance T at a wavelength of 450 nm 450 over 85% (iii-2) Average internal transmittance T at wavelength 450~600nm 450-600AVE over 90% (iii-3) The wavelength IR50 at which the internal transmittance is 50% is in the wavelength range of 660-700 nm.

[17] The phosphate glass is expressed as an oxide-based mass percentage, P2O 540-80% Al2O3 0.5-20% ΣR2O (where 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 (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) 0-40% CuO 0.5~40% An optical filter according to any one of [1] to

[16] , having a composition containing the following.

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

[17] , wherein the thickness of the resin film is 10 μm or less. [Examples]

[0137] Next, the present invention will be described in more detail with reference to examples. A UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, Model UH-4150) was used to measure each spectral characteristic. Unless otherwise specified, the spectral characteristics are measured at an incident angle of 0° (perpendicular to the main surface of the optical filter).

[0138] The dyes used in each example are as follows: Compound 1 (squallium compound): Synthesized according to International Publication No. 2017 / 135359. Compound 2 (merocyanine compound): Synthesized according to 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 (squallium compound): Synthesized according to the method described in Japanese Patent Publication No. 2017-110209.

[0139] [ka]

[0140] <Spectral properties of pigments in resin> A polyimide resin solution with a resin concentration of 8.5% by mass was prepared by dissolving polyimide resin ("C3G30G" (product name), refractive index 1.59) manufactured by Mitsubishi Gas Chemical Company in a γ-butyrolactone (GBL):cyclohexanone ratio of 1:1 (by mass). Each 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 resin, and the mixture was stirred and dissolved at 50°C for 2 hours to obtain a coating solution. The obtained coating solution was applied to alkali glass (SCHOTT, D263 glass, 0.2 mm thick) by spin coating, forming coating films with a thickness of approximately 1.0 μm. The spectral transmittance curves of the obtained coating films were measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The spectral properties of each of the compounds 1 to 4 above in polyimide resin are shown in the table below. Note that the spectral properties shown in the table below were evaluated using internal transmittance to avoid the influence of reflection at the air interface and glass interface.

[0141] [Table 1]

[0142] <Examples 1-1 to 1-2: Spectral characteristics of resin films> One of the dyes from compounds 1 to 4 was mixed at the concentrations shown in the table below into a polyimide resin solution (C3G30G, manufactured by Mitsubishi Gas Chemical Co., Ltd.) prepared in the same manner as when the spectral characteristics of the above compounds were calculated. The mixture was then stirred and dissolved at 50°C for 2 hours to obtain a resin solution. The obtained resin solution was applied to alkali glass (D263 glass, manufactured by SCHOTT, 0.2 mm thick) by spin coating to form a resin film with a thickness of 1.0 μm. The spectral transmittance curves of the obtained resin film were 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, to avoid the influence of reflection at the air interface and glass interface, the spectral characteristics shown in the table below were evaluated using internal transmittance. Examples 1-1 and 1-2 are for reference only.

[0143] [Table 2]

[0144] <Spectral properties of glass> As phosphated glass, phosphated glass 1 and phosphated glass 2 were prepared according to the following procedure. The raw materials were weighed and mixed to achieve the composition shown in the table below (mass %) based on oxides, placed in a crucible with an internal volume of approximately 400cc, and melted in an atmospheric environment for 2 hours. After that, the mixture was clarified and stirred. After casting into a rectangular mold measuring 100 mm (length) x 80 mm (width) x 20 mm (height) preheated to approximately 300°C to 500°C, the mixture was slowly cooled at approximately 1°C / min to form a plate measuring 40 mm (length) x 30 mm (width) with a thickness as shown in Table 4. Both sides were then optically polished to obtain a plate-shaped glass. In addition, NF50T, manufactured by AGC Corporation, was prepared as phthalic acid glass 1 and phthalic acid glass 2. The thicknesses of phthalic acid glass 1 and phthalic acid 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, to avoid the influence of reflection at the air interface and glass interface, the spectral characteristics shown in the table below were evaluated using internal transmittance. The obtained results are shown in the table below. Furthermore, the haze of each glass was determined according to JIS K 7136 using an automatic haze meter (manufactured by Tokyo Denshoku Co., Ltd., model number: TC-HIIIDPK). Furthermore, the spectral transmittance curves of phosphate glass 1 and fluorphosphate glass 1 are shown in Figure 5.

[0147] [Table 4]

[0148] From the above results, it was found that phosphate glasses 1 and 2 having a specific glass composition have a higher transmittance in the visible light region and a higher light-shielding property in the near-infrared light region compared to phosphate glasses 1 and 2. Furthermore, phosphate glasses 1 and 2 having a specific glass composition had a low haze. On the other hand, phosphate glasses 1 and 2 could maintain a high visible transmittance but were inferior in infrared light-shielding property. Also, in order to enhance the light-shielding property, as a result of increasing the plate thickness of the glass, the wavelength IR50 shifted to the short wavelength side and did not satisfy the desired spectral characteristics.

[0149] <Examples 2-1 to 2-8: Configuration of Optical Filter> [Example 2-1] On one main surface of the above phosphate glass 1 (thickness: 0.28 mm), films were formed in order from the first layer by vapor deposition so that the film materials and film thicknesses (nm) shown in the following table were obtained for each layer, and a total of 8 layers of a second dielectric multilayer film were formed. Hereinafter, the dielectric multilayer film having the configuration of Table 5 is referred to as "dielectric multilayer film 1".

[0150]

Table 5

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

[0152] [Example 2-2] As the first dielectric multilayer film and the second dielectric multilayer film, an optical filter was fabricated in the same manner as in Example 2-1, except that a dielectric multilayer film having the configuration shown in the following table was formed. Hereinafter, the dielectric multilayer film having the configuration shown in Table 6 is 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] As the first dielectric multilayer film and the second dielectric multilayer film, an optical filter was fabricated in the same manner as in Example 2-1, except that a dielectric multilayer film having the configuration shown in the following table was formed. Hereinafter, the dielectric multilayer film having the configuration shown in Table 7 is 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] As the first dielectric multilayer film, an optical filter was fabricated in the same manner as in Example 2-1, except that a dielectric multilayer film having the configuration shown in the following table was formed. Hereinafter, the dielectric multilayer film having the configuration shown in Table 8 is 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 fabricated 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 of Example 2-5 is shown in Table 11.

[0159] [Example 2-6] An optical filter was fabricated in the same manner as in Example 2-4, except that fluorine phosphate 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 with the configuration shown in the table below was deposited as the second dielectric multilayer film. Hereafter, the dielectric multilayer film with the configuration shown in Table 9 will be referred to as "dielectric multilayer film 5". The configuration of the optical filter of Example 2-6 is shown in Table 11.

[0160] [Table 9]

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

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

[0163] <Examples 2-1 to 2-8: Spectral characteristics of optical filters> For the optical filters in Examples 2-1 to 2-8 above, spectral transmittance curves at incident angles of 0 and 50 degrees, and spectral reflectance curves at incident angles of 5 and 50 degrees were measured using a UV-Vis spectrophotometer in the wavelength range of 350 to 1200 nm. In the measurement of 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 spectral characteristics data, the following characteristics were calculated as shown in the table below. Furthermore, the spectral transmittance curves (incident angle 0 and 50 degrees) and the reflectance curve when the second dielectric multilayer film side is the incident direction are also shown for the optical filters in Examples 2-1, 2-4, 2-5, and 2-6. Figures 6-13 show the cases with incidence angles of 5 degrees and 50 degrees. Examples 2-1 to 2-4 are examples, while Examples 2-5 to 2-8 are comparative examples.

[0164]

Table 10

[0165]

Table 11

[0166] From the above results, the optical filters of Examples 2-1 to 2-4, which are examples, have high transmittance in the visible light region and high shielding property in the near-infrared light region compared with Examples 2-5 to 2-8, which are comparative examples. Also, since the change in visible light transmittance is small even at a high incident angle, ripple generation is suppressed, and since the reflectance is small on any incident surface, stray light generation is also suppressed. It can be understood that the filter is as described above. On the other hand, the optical filter of Example 2-5, which is a comparative example, had large reflection characteristics on any incident surface. Also, the optical filter of Example 2-6, which is a comparative example, had large reflection characteristics on any incident surface, poor light shielding property in the near-infrared light region, and a large amount of absorption loss. Also, the optical filter of Example 2-7, which is a comparative example, had large reflection characteristics at glass surface incidence, poor light shielding property in the near-infrared light region, and a large amount of absorption loss. Also, the optical filter of Example 2-8, which is a comparative example, had poor light shielding property in the near-infrared light region.

[0167] Although the present invention has been described in detail and with reference to specific embodiments, it will be 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 filed on August 31, 2022 (Japanese Patent Application No. 2022-138361), the content of which is incorporated herein by reference.

Explanation of Reference Numerals

[0168] 1B Optical filter 11 Phosphate glass 12 Resin film 20A Second dielectric multilayer film 20B First Dielectric Multilayer Film

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