Optical filter

Abstract

The present invention relates to an optical filter having a first dielectric multilayer film, a resin film, a phosphate glass, and a second dielectric multilayer film in this order, in which the resin film contains a resin and a dye having a predetermined spectral characteristic, and the second dielectric multilayer film contains an H2 layer having a refractive index and a QWOT within a specific range. When the H2 layer closest to the phosphate glass is defined as the first H2 layer, a first M2 layer having a QWOT satisfying a specific range is included between the first H2 layer and the phosphate glass, and the optical filter satisfies all predetermined spectral characteristics (i-1)-(i-4).

Description

Technical Field

[0001] The present invention relates to an optical filter which allows visible light to be transmitted and blocks near infrared light. Background Art

[0002] In an imaging device using a solid-state imaging element, in order to reproduce color tones well and obtain a clear image, a filter is used that allows light in the visible light region (hereinafter also referred to as "visible light") to be transmitted and blocks light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light").

[0003] Such optical filters include various types such as dielectric thin films having different refractive indices alternately stacked on one or both surfaces of a transparent substrate (dielectric multilayer films), and reflective filters that reflect light to be shielded by utilizing interference of light.

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

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2014 / 002864

[0008] Patent Document 2: International Publication No. 2018 / 043564 Summary of the invention

[0009] Problems to be solved by the invention

[0010] For filters with dielectric multilayer films, since the optical film thickness of the dielectric multilayer film changes according to the incident angle of light, it is a problem that the spectral transmittance curve and the spectral reflectance curve change according to the incident angle. For example, depending on the number of stacked layers of the multilayer film, due to the interference caused by the reflected light at the interface of each layer, a sharp change in the transmittance in the visible light region, the so-called ripple, occurs. The larger the incident angle of the light, the more drastic the change is. As a result, the amount of light entering the visible light region changes at high incident angles, resulting in a problem of reduced image reproducibility. In particular, with the reduction in the height of camera modules in recent years, it is envisioned that they will be used under high incident angle conditions, so filters that are not easily affected by the incident angle are required.

[0011] In addition, in existing filters that utilize reflection of dielectric multilayer films, sometimes reflected light is reflected on the lens surface and then incident, or light reflected on the sensor surface is reflected on the dielectric multilayer film surface and then incident, thereby generating light outside the originally intended optical path, so-called stray light. When such filters are used, glare, ghosting, or image quality degradation may occur in solid-state imaging elements. In particular, with the high-quality image of camera modules in recent years, filters that are less likely to generate stray light are required.

[0012] An object of the present invention is to provide an optical filter which suppresses ripples and stray light in the visible light region and has excellent transmittance in the visible light region and shielding properties in the near infrared light region.

[0013] Means used to solve problems

[0014] The present invention provides an optical filter having the following structure.

[0015] [1] An optical filter comprising, in order, a first dielectric multilayer film, a resin film, a phosphate glass film, and a second dielectric multilayer film, wherein:

[0016] The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin.

[0017] The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices,

[0018] The second dielectric multilayer film includes at least one H2 layer, the H2 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5.

[0019] When the layer closest to the phosphate glass in the H2 layer is set as the first H2 layer,

[0020] A first M2 layer is included between the first H2 layer and the phosphate glass, the first M2 layer being composed of a single layer satisfying a QWOT of 1.2 or more and 1.8 or less or a plurality of layers satisfying a total QWOT of 1.2 or more and 1.8 or less,

[0021] The filter satisfies all of the following spectral characteristics (i-1) to (i-4):

[0022] (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%;

[0023] (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm450-550(50deg)AVE More than 85%;

[0024] (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%;

[0025] (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

[0026] [2] An optical filter comprising, in order, a first dielectric multilayer film, a resin film, a phosphate glass film, and a second dielectric multilayer film, wherein:

[0027] The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin.

[0028] The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices,

[0029] The first dielectric multilayer film includes at least one H1 layer, the H1 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5.

[0030] When the layer closest to the resin film in the H1 layer is set as the first H1 layer,

[0031] A first M1 layer is included between the first H1 layer and the resin film, the first M1 layer being composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.8,

[0032] The filter satisfies all of the following spectral characteristics (i-1) to (i-4):

[0033] (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%;

[0034] (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%;

[0035] (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%;

[0036] (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

[0037] Effects of the Invention

[0038] According to the present invention, it is possible to provide an optical filter which suppresses ripples and stray light in the visible light region and has excellent transmittance in the visible light region and shielding properties in the near infrared light region. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a cross-sectional view schematically showing an example of an optical filter according to an embodiment.

[0040] Figure 2 It is a schematic cross-sectional view showing the structure of the filter of Example 2-1.

[0041] Figure 3 It is a schematic cross-sectional view showing the structure of the filter of Example 2-2.

[0042] Figure 4 A schematic cross-sectional view showing the structure of the optical filter of Example 2-3.

[0043] Figure 5 is a graph showing the spectral transmittance curve of glass.

[0044] Figure 6 Graph showing the spectral transmittance curve of the optical filter of Example 2-1.

[0045] Figure 7 Graph showing the spectral reflectance curve of the optical filter of Example 2-1.

[0046] Figure 8 Graph showing the spectral transmittance curves of the optical filters of Examples 2-4.

[0047] Fig. 9 Graph showing the spectral reflectance curves of the optical filters of Examples 2-4.

[0048] Fig.10 Graph showing the spectral transmittance curves of the optical filters of Examples 2-5.

[0049] Fig.11 Graph showing the spectral reflectance curves of the optical filters of Examples 2-5.

[0050] Fig.12 Graphs showing spectral transmittance curves of the optical filters of Examples 2-6.

[0051] Fig.13 Graph showing the spectral reflectance curves of the optical filters of Examples 2-6. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present invention will be described.

[0053] In this specification, a near infrared absorbing dye may be simply referred to as a “NIR dye”, and an ultraviolet absorbing dye may be simply referred to as a “UV dye”.

[0054] In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulae. A pigment containing compound (I) is also referred to as pigment (I), and the same applies to other pigments.

[0055] In this specification, the internal transmittance refers to the transmittance obtained by deducting the influence of interface reflection from the measured transmittance, which is represented by the formula {measured transmittance (incident angle 0 degrees) / (100-reflectivity (incident angle 5 degrees))}×100.

[0056] In this specification, when the transmittance of a substrate and the transmittance spectrum of a resin film including the case where the resin contains a pigment are described as "transmittance", all of them are "internal transmittance". On the other hand, the transmittance measured by dissolving a pigment in a solvent such as dichloromethane, the transmittance of a dielectric multilayer film, and the transmittance of an optical filter having a dielectric multilayer film are measured transmittances.

[0057] In this specification, the transmittance of a specific wavelength range, for example, 90% or more, means that the transmittance in the entire wavelength range is not less than 90%, that is, the minimum transmittance in the wavelength range is 90% or more. Similarly, the transmittance of a specific wavelength range, for example, 1% or less, means that the transmittance in the entire wavelength range is not more than 1%, that is, the maximum transmittance in the wavelength range is less than 1%. The same is true for the internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic mean of the transmittance and internal transmittance per 1nm in the wavelength range.

[0058] Spectral properties can be measured using a UV-visible spectrophotometer.

[0059] In the present specification, "to" indicating a numerical range includes the upper limit and the lower limit.

[0060] <Filter>

[0061] Figure 1This is a cross-sectional view showing an optical filter (hereinafter also referred to as "this optical filter") according to an embodiment of the present invention. This optical filter 1B has a first dielectric multilayer film 20B, a resin film 12, a phosphate glass 11, and a second dielectric multilayer film 20A in this order. Here, the resin film contains a resin and a pigment having a maximum absorption wavelength in the range of 690nm to 800nm ​​in the resin.

[0062] In the present invention, as described later, at least one of the first dielectric multilayer film and the second dielectric multilayer film has a small reflection characteristic even at a high incident angle, thereby suppressing stray light. In addition, the light shielding property of the filter is substantially ensured by the absorption property of the phosphate glass. Since the absorption property is not affected by the incident angle of light, it is possible to suppress ripples in the visible light region while achieving excellent transmittance in the visible light region and excellent shielding property in the near infrared light region as a whole as the filter.

[0063] <Filter Characteristics>

[0064] The optical filter of the present invention satisfies all of the following spectral characteristics (i-1) to (i-4).

[0065] (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%;

[0066] (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%;

[0067] (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%;

[0068] (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

[0069] This filter, which satisfies all spectral characteristics (i-1) to (i-4), has high transmittance in the visible light region as shown in characteristic (i-1) and high shielding properties in the near infrared region as shown in characteristic (i-3). In addition, as shown in characteristics (i-2) and (i-4), the change in spectral characteristics at high incident angles is small, and ripples in the visible light region are suppressed.

[0070] Satisfying the spectral characteristics (i-1) and (i-2) means that the transmittance in the visible light region of 450 nm to 550 nm is excellent even at a high incident angle.

[0071] Average transmittance T 450-550(0deg)AVE It is preferably 88% or more, and more preferably 91% or more.

[0072] Average transmittance T 450-550(50deg)AVE It is preferably 87% or more, and more preferably 89% or more.

[0073] Satisfying the spectral characteristics (i-3) and (i-4) means that the transmittance in the near-infrared light region of 750 nm to 1000 nm is excellent even at a high incident angle.

[0074] Average transmittance T 750-1000(0deg)AVE It is preferably 1.5% or less, and more preferably 1% or less.

[0075] Average transmittance T 750-1000(50deg)AVE It is preferably 1% or less, and more preferably 0.5% or less.

[0076] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-5) to (i-8).

[0077] (i-5) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 of the wavelength 750nm to 1000nm 750-1000(5deg)AVE Less than 3%;

[0078] (i-6) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 at wavelengths of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0079] (i-7) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0080] (i-8) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at wavelengths of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0081] Spectral characteristics (i-5) and (i-6) define the reflection characteristics on the second dielectric multilayer film side, and spectral characteristics (i-7) and (i-8) define the reflection characteristics on the second dielectric multilayer film side at high incident angles.

[0082] Since the reflectance in the visible light region and the near-infrared light region is low even at a high incident angle, it is possible to suppress reflection on the second medium multilayer film surface which is a cause of stray light.

[0083] Average reflectivity R2 750-1000(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less.

[0084] Average reflectivity R2 450-600(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less.

[0085] Average reflectivity R2 750-1000(50deg)AVE It is more preferably 3% or less, and even more preferably 2% or less.

[0086] Average reflectivity R2 450-600(50deg)AVE It is more preferably 4% or less, and further preferably 3% or less.

[0087] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-9) to (i-12).

[0088] (i-9) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(0deg)AVE Below 7%;

[0089] (i-10) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(50deg)AVE Below 7%;

[0090] (i-11) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the wavelength IR30 when the transmittance is 30% (0deg) In the wavelength range of 630nm to 680nm;

[0091] (i-12) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the wavelength IR30 when the transmittance is 30% (50deg) In the wavelength range of 630nm ~ 680nm.

[0092] Satisfying the spectral characteristics (i-9) and (i-10) means that the light shielding property in the near-infrared light region of 1000 nm to 1200 nm is excellent even at a high incident angle.

[0093] Average transmittance T 1000-1200(0deg)AVE It is more preferably 5% or less, and even more preferably 3% or less.

[0094] Average transmittance T 1000-1200(50deg)AVE It is more preferably 3% or less, and even more preferably 2% or less.

[0095] Satisfying the spectral characteristics (i-11) and (i-12) means shielding light in the near-infrared region and efficiently allowing visible transmission light to enter even at a high incident angle.

[0096] Wavelength IR30 (0deg) The wavelength is more preferably within a range of 640 nm to 675 nm, and even more preferably within a range of 640 nm to 670 nm.

[0097] Wavelength IR30 (50deg) The wavelength is more preferably within a range of 640 nm to 675 nm, and even more preferably within a range of 640 nm to 670 nm.

[0098] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-13) to (i-16).

[0099] (i-13) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(5deg)AVE Less than 3%;

[0100] (i-14) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0101] (i-15) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0102] (i-16) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0103] Spectral characteristics (i-13) and (i-14) specify the reflection characteristics on the first dielectric multilayer film side, and spectral characteristics (i-15) and (i-16) specify the reflection characteristics on the first dielectric multilayer film side at high incident angles.

[0104] Since the reflectivity is low even at a high incident angle, it is possible to suppress reflection on the dielectric multilayer film surface which causes stray light.

[0105] Average reflectivity R1 750-1000(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less.

[0106] Average reflectivity R1 450-600(5deg)AVE It is more preferably 1.5% or less, and even more preferably 1% or less.

[0107] Average reflectivity R1 750-1000(50deg)AVE It is more preferably 3.5% or less, and even more preferably 2% or less.

[0108] Average reflectivity R1 450-600(50deg)AVE It is more preferably 4% or less, and even more preferably 3.5% or less.

[0109] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-17) to (i-20).

[0110] (i-17) Average transmittance T 450-550(0deg)AVE With the average transmittance T 450-550(50deg)AVE The absolute value of the difference is less than 3.5%;

[0111] (i-18) Average transmittance T 750-1000(0deg)AVE With the average transmittance T 750-1000(50deg)AVE The absolute value of the difference is less than 1.5%;

[0112] (i-19) Average transmittance T 1000-1200(0deg)AVE With the average transmittance T 1000-1200(50deg)AVE The absolute value of the difference is less than 1.5%;

[0113] (i-20) Wavelength IR30 (0deg) With wavelength IR30 (50deg) The absolute value of the difference is less than 15 nm.

[0114] Satisfying spectral characteristics (i-17) to (i-19) means that the transmittance in the visible light region of 450nm to 600nm and the near-infrared light region of 750nm to 1200nm is not easily changed even at high incident angles, that is, ripples are suppressed.

[0115] The absolute value of the spectral characteristic (i-17) is more preferably 3.2% or less, and further preferably 3% or less.

[0116] The absolute value of the spectral characteristic (i-18) is more preferably 1% or less, and further preferably 0.5% or less.

[0117] The absolute value of the spectral characteristic (i-19) is more preferably 1.3% or less, and further preferably 1.2% or less.

[0118] Satisfying the spectral characteristic (i-20) means that the spectral transmittance curve in the range of 630 nm to 680 nm is unlikely to shift even at a high incident angle.

[0119] The absolute value of the spectral characteristic (i-20) is more preferably 10 nm or less, and further preferably 8 nm or less.

[0120] The optical filter of the present invention preferably further satisfies the following spectral characteristic (i-21).

[0121] (i-21) When the second dielectric multilayer film side is taken as the incident direction, the average value of the absorption loss amount defined below is greater than or equal to 95% within the wavelength range of 750 nm to 1000 nm.

[0122] (Absorption loss) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectivity at an incident angle of 5 degrees)

[0123] Satisfying the spectral characteristic (i-21) means having both transmittance in the visible light region and shielding property in the near-infrared light region.

[0124] The average value of the absorption loss is more preferably 96% or more, and further preferably 97% or more.

[0125] The optical filter of the present invention preferably further satisfies the following spectral characteristic (i-22).

[0126] (i-22) When the second dielectric multilayer film side is taken as the incident direction, the minimum value of the absorption loss is greater than 90% within the wavelength range of 750nm to 1000nm.

[0127] Satisfying the spectral characteristic (i-22) means having both transmittance in the visible light region and shielding properties in the near-infrared light region.

[0128] The minimum value of the absorption loss is more preferably 92% or more, and further preferably 94% or more.

[0129] The optical filter of the present invention preferably further satisfies the following spectral characteristic (i-23).

[0130] (i-23) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R2 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R2 n(5deg) The number of n that is less than 1% is 200 or more.

[0131] The spectral characteristic (i-23) defines the reflection characteristic on the second dielectric multilayer film side, which means that the reflectance is small and reflection on the dielectric multilayer film surface that causes stray light can be suppressed.

[0132] Reflectivity R2 n(5deg) The number of n which is 1% or less is more preferably 220 or more, and further preferably 230 or more.

[0133] The optical filter of the present invention preferably further satisfies the following spectral characteristic (i-24).

[0134] (i-24) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R1 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R1 n(5deg) The number of n that is less than 1% is 150 or more.

[0135] The spectral characteristic (i-24) defines the reflection characteristic on the first dielectric multilayer film side, which means that the reflectance is small and reflection on the dielectric multilayer film surface that causes stray light can be suppressed.

[0136] Reflectivity R1 n(5deg) The number of n which is 1% or less is more preferably 180 or more, and further preferably 200 or more.

[0137] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-25) to (i-28).

[0138] (i-25) In the spectral transmittance curve under the condition of incident angle of 0 degrees, the minimum transmittance T at wavelength 450nm to 550nm 450-550(0deg)MIN More than 83%;

[0139] (i-26) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the maximum transmittance T at a wavelength of 450nm to 550nm is 450-550(0deg)MAX More than 90%;

[0140] (i-27) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the maximum transmittance T 750-1000(0deg)MAX Less than 1.2%;

[0141] (i-28) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the maximum transmittance T 1000-1200(0deg)MAX Below 7%.

[0142] Satisfying the characteristics (i-25) and (i-26) means that the transmittance of visible light is excellent, and satisfying the characteristics (i-27) and (i-28) means that the shielding property in the near-infrared region is excellent.

[0143] Minimum transmittance T 450-550(0deg)MIN It is more preferably 85% or more, and even more preferably 87% or more.

[0144] Maximum transmittance T 450-550(0deg)MAX It is more preferably 92% or more, and even more preferably 94% or more.

[0145] Maximum transmittance T 750-1000(0deg)MAX It is more preferably 1% or less, and even more preferably 0.9% or less.

[0146] Maximum transmittance T 1000-1200(0deg)MAX It is more preferably 5% or less, and even more preferably 4% or less.

[0147] <Second dielectric multilayer film>

[0148] In the present optical filter, the second dielectric multilayer film preferably suppresses reflection in the visible light region and the near-infrared light region even at a high incident angle. In the present invention, since the second dielectric multilayer film suppresses reflection in the visible light region and the near-infrared light region, it is possible to obtain an optical filter that reduces the generation of ripples in the visible light region and suppresses stray light because the spectral characteristics are not easily changed for light at a high incident angle.

[0149] The second dielectric multilayer film is a multilayer film comprising a plurality of layers with different refractive indices and these layers are alternately stacked. More specifically, the second dielectric multilayer film 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 the second dielectric multilayer film is a multilayer film obtained by alternately stacking two or more dielectric layers therein.

[0150] The refractive index of the high refractive index layer is preferably 1.6 or more at a wavelength of 500 nm, and more preferably 2.2 to 2.5. Examples of materials for the high refractive index layer include Ta2O5, TiO2, TiO, Ti2O3, and Nb2O5. Other commercially available products include OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), and OA600 (a mixture of Ta2O5 and TiO2) manufactured by Canon Optron Co., Ltd. Among them, TiO2 is preferred in terms of film-forming properties, reproducibility of the refractive index, stability, and the like.

[0151] The refractive index of the medium refractive index layer is preferably greater than or equal to 1.6 and less than 2.2 at a wavelength of 500nm. As the material of the medium refractive index layer, for example, ZrO2, Nb2O5, Al2O3, HfO2, OM-4 and OM-6 (a mixture of Al2O3 and ZrO2) sold by Canon Optron Co., Ltd., OA-100, H4 and M2 (aluminum oxide-lanthanum oxide) sold by Merck, etc. Among them, from the aspects of film forming properties, reproducibility of refractive index, stability, etc., Al2O3 compounds and mixtures of Al2O3 and ZrO2 are preferred.

[0152] The refractive index of the low refractive index layer is preferably less than 1.6 at a wavelength of 500 nm, and more preferably 1.38 to 1.5. Examples of the material of the low refractive index layer include SiO2, SiO x N y , MgF2, etc. Other commercially available products include S4F and S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Co., Ltd. Among them, SiO2 is preferred in terms of film-forming reproducibility, stability, and economy.

[0153] (Configuration of the Second Dielectric Multilayer Film)

[0154] Figure 2 This is a cross-sectional schematic diagram showing the structure of the optical filter produced in Example 2-1 described later. In Example 2-1, the second dielectric multilayer film 20A adopts a laminated structure in which TiO2 (refractive index at 500nm: 2.467) as a high refractive index layer and SiO2 (refractive index at 500nm: 1.483) as a low refractive index layer are alternately laminated. However, in this embodiment, the structure is not limited to this, and the above materials can be arbitrarily selected.

[0155] like Figure 2 As shown, the second dielectric multilayer film includes at least one H2 layer, and the H2 layer satisfies a refractive index of 1.8 or more and 2.5 or less at 500 nm and a QWOT (Quarter Wave Optical Thickness) of 1.1 or more and 3.5 or less. The refractive index of the H2 layer is preferably 1.9 or more and 2.5 or less, more preferably 2.0 or more and 2.5 or less, and further preferably 2.1 or more and 2.5 or less.

[0156] Here, QWOT can be calculated by the following formula.

[0157] QWOT = (physical film thickness / central wavelength) × 4 × refractive index

[0158] It should be noted that the unit of the 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.

[0159] like Figure 2 As shown, when the H2 layer closest to the phosphate glass is set as the first H2 layer, the second dielectric multilayer film includes a first M2 layer between the first H2 layer and the phosphate glass, and the first M2 layer is composed of a plurality of continuous layers satisfying that the total QWOT of each layer is greater than 1.2 and less than 1.8.

[0160] It should be noted that in Figure 2In the example shown, when the layer closest to the phosphate glass is set as the first layer, the first M2 layer is composed of four layers from the first layer to the fourth layer, but as long as the total QWOT of each layer is 1.2 or more and 1.8 or less, the first M2 layer can be composed of any number of layers. That is, the first M2 layer can also be a single layer that satisfies the 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 6 layers or less, and more preferably 3 layers or less.

[0161] The inventors of the present invention have discovered that: by having the second dielectric multilayer film have the above-mentioned structure, the first M2 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smooth. Therefore, reflection is suppressed in a wide wavelength range from the visible light region to the near-infrared light region, and the incident angle dependence of the reflection characteristics is suppressed, thereby being able to suppress stray light.

[0162] More specifically, the second dielectric multilayer film has the above-described structure, and thus the following characteristics can be obtained.

[0163] (i-5) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 of the wavelength 750nm to 1000nm 750-1000(5deg)AVE Less than 3%;

[0164] (i-6) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 at wavelengths of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0165] (i-7) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0166] (i-8) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at wavelengths of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0167] In this embodiment, the first M2 layer can be arranged at any position between the first H2 layer and the phosphate glass. Figure 2In the embodiment, the first M2 layer is composed of all the layers (1st to 4th layers) contained between the phosphate glass and the first H2 layer, but the layer from the closest to the phosphate glass (1st layer) to the third closest to the phosphate glass (3rd layer) can be set as the first M2 layer (in this case, the total QWOT of the 1st to 3rd layers is 1.423), and SiO2 (4th layer) which is the layer closest to the first H2 layer can be set as an optional layer.

[0168] In addition, when there are multiple single layers satisfying QWOT of greater than 1.2 and less than 1.8 or multiple continuous layers satisfying QWOT of greater than 1.2 and less than 1.8 between the first H2 layer and the phosphate glass, any one of the corresponding single layers or multiple continuous layers is set as the first M2 layer, and the other layers are set as optional layers.

[0169] As described above, in this embodiment, as long as the first M2 layer is included between the first H2 layer and the phosphate glass, an optional layer may be included between the first H2 layer and the phosphate glass within a range that does not hinder the effect of the present invention. The optional 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 preferred that there is no optional layer between the first H2 layer and the phosphate glass. That is, it is preferred that the first H2 layer, the first M2 layer, and the phosphate glass are formed continuously.

[0170] As materials for the optional layers, there can be mentioned the above-mentioned high refractive index layer, medium refractive index layer and low refractive index layer.

[0171] In addition, if Figure 3 As shown, the second dielectric multilayer film may be composed of two or more H2 layers. Figure 3 As shown in FIG. 1 , when the second layer close to the phosphate glass is set as the second H2 layer, it is preferred to include a second M2 layer between the first H2 layer and the second H2 layer, and the second M2 layer is composed of a plurality of continuous layers satisfying that the total QWOT of each layer is 1.2 or more and 2.1 or less. By including the second M2 layer between the first H2 layer and the second H2 layer, the second M2 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smooth, so that reflection is further suppressed in a wide wavelength range from the visible light region to the near infrared light region.

[0172] It should be noted that in Figure 3In the example shown in , the second M2 layer is composed of three layers from the 6th layer to the 8th layer, but as long as the total QWOT of each layer is 1.2 or more and 2.1 or less, the second M2 layer can also be composed of any number of layers. That is, the second M2 layer can also be a single layer that satisfies 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 6 layers or less, and more preferably 3 layers or less.

[0173] In addition, in this embodiment, if Figure 4 As shown, it is preferred that two single layers satisfying a QWOT of 1.2 or more and 2.1 or a plurality of continuous layers satisfying a total QWOT of 1.2 or more and 2.1 or less are included between the first H2 layer and the second H2 layer. Figure 4 As shown, in the corresponding single layer or multiple continuous layers, the layer closest to the second H2 layer is set as the second M2 layer, and the layer second closest to the second H2 layer is set as the third M2 layer. That is, the second dielectric multilayer film preferably includes a third M2 layer between the first H2 layer and the second M2 layer in addition to the second M2 layer, and the third M2 layer is composed of a single layer satisfying QWOT of 1.2 or more and 2.1 or a plurality of layers satisfying QWOT of 1.2 or more and 2.1 or less in total.

[0174] Since the second dielectric multilayer film has such a structure, the third M2 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smooth, so that reflection is further suppressed in a wide wavelength range from the visible light region to the near infrared light region.

[0175] As described above, as long as the layer close to the second H2 layer is the second M2 layer, the second M2 layer and the third M2 layer can be arranged at any position.

[0176] It should be noted that in Figure 4 In the example shown, there are two single layers satisfying QWOT of greater than 1.2 and less than 2.1 or multiple continuous layers (second M2 layer and third M2 layer) satisfying the total QWOT of greater than 1.2 and less than 2.1 between the first H2 layer and the second H2 layer, but it may also include more than three corresponding single layers or multiple continuous layers.

[0177] In addition, between the first H2 layer and the second H2 layer, in addition to the second M2 layer and the third M2 layer, an optional layer may be included within the scope of not hindering the effect of the present invention. As the optional layer, the same optional layer as above can be listed. However, from the viewpoint of improving productivity, it is preferred that there is no optional layer. That is, it is most preferred that the second H2 layer, the second M2 layer, the third M2 layer and the first H2 layer are continuously formed.

[0178] Even in the case where there is no third M2 layer, it is preferred that no optional layer exists and the second H2 layer, the second M2 layer, and the first H2 layer are continuously formed.

[0179] In addition, from the viewpoint of further suppressing reflection, it is preferred that the QWOT of the first H2 layer and the second H2 layer in the second dielectric multilayer film are different from each other. In addition, from the same viewpoint, it is preferred that the QWOT of a single layer constituting the first M2 layer, the second M2 layer and the third M2 layer or the total value of the QWOT of a plurality of continuous layers are different from each other.

[0180] It should be noted that the total number of laminated dielectric layers in the second dielectric multilayer film is preferably 10 to 30, and more preferably 10 to 20. When the total number of laminated dielectric layers is within the above range, the film thickness per layer can be prevented from increasing.

[0181] The overall thickness of the second dielectric multilayer film is preferably 0.5 μm to 2.0 μm, and more preferably 0.5 μm to 1.0 μm. When the thickness of the second dielectric multilayer film is within the above range, the thickness of each layer can be prevented from increasing.

[0182] The second dielectric multilayer film and the first dielectric multilayer film described later can be formed by, for example, a vacuum film forming process such as CVD, sputtering, or vacuum evaporation; or a wet film forming process such as spraying or dipping.

[0183] <First dielectric multilayer film>

[0184] In the present optical filter, the first dielectric multilayer film preferably suppresses reflection in the visible light region and the near-infrared light region. By suppressing reflection in the visible light region and the near-infrared light region through the first dielectric multilayer film, it is possible to obtain an optical filter that reduces the generation of ripples in the visible light region and suppresses stray light because the spectral characteristics are not easily changed for light with a high incident angle.

[0185] The first dielectric multilayer film is a multilayer film including a plurality of layers with different refractive indices and these layers are alternately stacked. More specifically, the first dielectric multilayer film 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 the first dielectric multilayer film is a multilayer film obtained by alternately stacking two or more dielectric layers therein.

[0186] The refractive index and material of the high refractive index layer, the medium refractive index layer, and the low refractive index layer may be the same as those of the second dielectric multilayer film.

[0187] (Constitution of the First Dielectric Multilayer Film)

[0188] In this embodiment, if Figure 2As shown, the first dielectric multilayer film includes at least one H1 layer, and the H1 layer satisfies a refractive index of 1.8 to 2.5 at 500 nm and a QWOT of 1.1 to 3.5. The refractive index of the H1 layer is preferably 1.9 to 2.5, more preferably 2.0 to 2.5, and further preferably 2.1 to 2.5.

[0189] like Figure 2 As shown, when the H1 layer closest to the resin film is set as the first H1 layer, the first dielectric multilayer film preferably includes a first M1 layer between the first H1 layer and the resin film, and the first M1 layer is composed of a plurality of continuous layers satisfying that the total QWOT of each layer is greater than 1.2 and less than 1.8.

[0190] That is, similarly to the second dielectric multilayer film including the first H2 layer and the first M2 layer, the first dielectric multilayer film preferably also includes the first H1 layer and the first M1 layer. Since the first dielectric multilayer film has the above-mentioned structure, the first M1 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smooth, so when incident light is incident from the resin surface of the filter, reflection is further suppressed in a wide wavelength range from the visible light region to the infrared light region.

[0191] More specifically, since the first dielectric multilayer film has the above-described structure, the following characteristics can be obtained.

[0192] (i-13) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(5deg)AVE Less than 3%;

[0193] (i-14) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0194] (i-15) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0195] (i-16) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0196] It should be noted that the first M1 layer can be disposed at any position between the first H1 layer and the resin film. Figure 2 In the embodiment, the first M1 layer is constituted by all the layers (1st to 4th layers) contained between the resin film and the first H1 layer, but the layer closest to the resin film (1st layer) to the layer third closest to the resin film (3rd layer) can be set as the first M1 layer (in this case, the total QWOT of the 1st to 3rd layers is 1.423), and SiO2 (4th layer) which is the layer closest to the first H1 layer can be set as an optional layer.

[0197] In addition, when there are multiple single layers satisfying QWOT of greater than 1.2 and less than 1.8 or multiple continuous layers satisfying QWOT of greater than 1.2 and less than 1.8 between the first H1 layer and the resin film, any one of the corresponding single layers or multiple continuous layers is set as the first M1 layer, and the other layers are set as optional layers.

[0198] As such, an optional layer may be included between the first H1 layer and the resin layer within a range that does not hinder the effects of the present invention. For example, the optional layer may be included between the resin layer and the first M1 layer, or between the first M1 layer and the first H1 layer. Examples of the optional layer include the same optional layers as described above.

[0199] In addition, if Figure 3 As shown, the first dielectric multilayer film may be a structure including two or more H1 layers. In this case, when the second layer close to the resin film is set as the second H1 layer, it is preferred to include a second M1 layer between the first H1 layer and the second H1 layer, and the second M1 layer is composed of a plurality of continuous layers satisfying QWOT of 1.2 or more and 2.1 or less in total. By having the second M1 layer between the first H2 layer and the second H2 layer, the second M1 layer functions as an intermediate refractive index layer, and the spectral waveform becomes smooth, so that reflection is further suppressed when incident from the resin surface of the filter.

[0200] It should be noted that the second M1 layer can be composed of any number of layers as long as the total QWOT of each layer is greater than or equal to 1.2 and less than or equal to 2.1. That is, the second M1 layer can be a single layer satisfying QWOT of greater than or equal to 1.2 and less than or equal to 2.1. However, from the perspective of improving productivity, the second M1 layer is preferably composed of 6 layers or less, and more preferably 3 layers or less.

[0201] In addition, in this embodiment, if Figure 4As shown, it is preferred that two single layers satisfying QWOT of 1.2 or more and 2.1 or a plurality of continuous layers satisfying QWOT of 1.2 or more and 2.1 or less are included between the first H1 layer and the second H1 layer. In this case, in the corresponding single layer or the plurality of continuous layers, the layer closest to the second H1 layer is set as the second M1 layer, and the layer second closest to the second H1 layer is set as the third M1 layer. That is, the first dielectric multilayer film preferably includes a third M1 layer between the first H1 layer and the second M1 layer in addition to the second M1 layer, and the third M1 layer is composed of a single layer satisfying QWOT of 1.2 or more and 2.1 or a plurality of layers satisfying QWOT of 1.2 or more and 2.1 or less.

[0202] Since the first dielectric multilayer film has such a structure, the third M1 layer functions as an intermediate refractive index layer and the spectral waveform becomes smooth, so that reflection is further suppressed in a wide wavelength range from the visible light region to the near infrared light region.

[0203] As described above, as long as the layer close to the second H1 is the second M1 layer, the second M1 layer and the third M1 layer may be arranged at any position.

[0204] It should be noted that in Figure 4 In the example shown, there are two single layers satisfying QWOT of greater than 1.2 and less than 2.1 or multiple continuous layers (second M1 layer and third M1 layer) satisfying the total QWOT of greater than 1.2 and less than 2.1 between the first H1 layer and the second H1 layer, but it may also include more than three corresponding single layers or multiple layers.

[0205] In addition, between the first H1 layer and the second H1 layer, in addition to the second M1 layer and the third M1 layer, an optional layer may be included within the range that does not hinder the effect of the present invention. As the optional layer, the same optional layers as above can be listed. However, from the viewpoint of improving productivity, it is preferred that there is no optional layer. That is, it is most preferred that the second H1 layer, the second M1 layer, the third M1 layer and the first H1 layer are formed continuously.

[0206] Even in the case where the third M1 layer is not present, it is preferred that no optional layer exists and the second H1 layer, the second M1 layer, and the first H1 layer are continuously formed.

[0207] In addition, from the viewpoint of further suppressing reflection, it is preferred that the QWOT of the first H1 layer and the second H1 layer in the first dielectric multilayer film are different from each other. In addition, from the same viewpoint, it is preferred that the QWOT of a single layer or the total value of the QWOT of a plurality of continuous layers constituting the first M1 layer, the second M1 layer and the third M1 layer are different from each other.

[0208] It should be noted that the total number of laminated dielectric layers in the first dielectric multilayer film is preferably 10 to 30, and more preferably 10 to 20. When the total number of laminated dielectric layers is within the above range, the film thickness per layer can be prevented from increasing.

[0209] The overall thickness of the first dielectric multilayer film is preferably 0.5 μm to 2.0 μm, and more preferably 0.5 μm to 1.0 μm. When the thickness of the first dielectric multilayer film is within the above range, the thickness of each layer can be prevented from increasing.

[0210] <Phosphate glass>

[0211] It is preferable that phosphate glass satisfies all of the following spectral characteristics (ii-1) to (ii-3).

[0212] (ii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 92%;

[0213] (ii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%;

[0214] (ii-3) the wavelength IR50 at which the internal transmittance is 50% is within the wavelength range of 625 nm to 650 nm;

[0215] (ii-4) Average internal transmittance T at wavelengths of 750 nm to 1000 nm 750-1000AVE Less than 2.5%;

[0216] (ii-5) Average internal transmittance T at wavelengths of 1000 nm to 1200 nm 1000-1200AVE Below 7%.

[0217] Satisfying the spectral characteristic (ii-1) means that the transmittance in the blue light region is excellent, and satisfying the spectral characteristic (ii-2) means that the transmittance in the visible light region of 450 nm to 600 nm is excellent.

[0218] Internal transmittance T 450 It is more preferably 93% or more, and even more preferably 95% or more.

[0219] Average internal transmittance T 450-600AVE It is more preferably 94% or more, and even more preferably 95% or more.

[0220] By satisfying the spectral characteristic (ii-3), it means that light in the near-infrared region is shielded and visible transmission light is effectively allowed to enter.

[0221] The wavelength IR50 is more preferably in the range of 625 nm to 645 nm, and further preferably in the range of 625 nm to 640 nm.

[0222] Satisfying the spectral characteristic (ii-4) means that the light shielding property in the near-infrared light region of 750 nm to 1000 nm is excellent.

[0223] T 750-1000AVE It is more preferably 2% or less, and even more preferably 1.2% or less.

[0224] Satisfying the spectral characteristic (ii-5) means that the light shielding property in the near-infrared light region of 1000 nm to 1200 nm is excellent. 1000-1200AVE It is more preferably 6.8% or less, and even more preferably 6.5% or less.

[0225] In the present invention, the phosphate glass preferably absorbs near-infrared light starting from the region of 625nm to 650nm as shown in the above characteristic (ii-3), and exhibits high light shielding properties above 750nm as shown in the above characteristic (ii-4). Thus, a substrate capable of compensating for the light shielding properties of the above dielectric multilayer film can be obtained.

[0226] In the present invention, phosphate glass refers to glass containing 40% or more of P2O5 in terms of mass percentage based on oxides. In addition, phosphate glass preferably contains copper ions. By containing copper ions that absorb light with a wavelength of around 900nm, near-infrared light of 700nm to 1200nm can be blocked. It should be noted that phosphate glass also includes silicon phosphate glass in which a part of the skeleton of the glass is composed of SiO2.

[0227] For example, the phosphate glass preferably contains the following glass-constituting components. It should be noted that the content ratios of the following glass-constituting components are expressed as mass percentages based on oxides.

[0228] P2O5 40%~80%

[0229] Al2O3 0.5%~20%

[0230] ΣR2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O and Cs2O, and ΣR2O is the total amount of R2O) 0.5% to 20%

[0231] ΣR'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO and ZnO, and ΣR'O is the total amount of R'O) 0% to 40%

[0232] CuO 0.5%~40%

[0233] P2O5 is a main component of glass and is used to improve near-infrared cutoff. If the content of P2O5 is 40% or more, its effect can be fully obtained. If the content of P2O5 is 80% or less, it is not easy to cause problems such as glass becoming unstable and reduced weather resistance. Therefore, the content of P2O5 is preferably 40% to 80%, more preferably 45% to 78%, further preferably 50% to 77%, further more preferably 55% to 76%, and most preferably 60% to 75%.

[0234] Al2O3 is the main component of glass and is used to improve the strength of glass, improve the weather resistance of glass, etc. If the content of Al2O3 is 0.5% or more, its effect can be fully obtained. If the content of Al2O3 is 20% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced. Therefore, the content of Al2O3 is preferably 0.5% to 20%, more preferably 1.0% to 20%, further preferably 2.0% to 18%, further more preferably 3.0% to 17%, particularly preferably 4.0% to 16%, and most preferably 5.0% to 15.5%.

[0235] R2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O and Cs2O) is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. If the total amount of R2O (ΣR2O) is 0.5% or more, its effect can be fully obtained. If the total amount of R2O (ΣR2O) is 20% or less, the glass is not easy to become unstable, so it is preferred. Therefore, the total amount of R2O (ΣR2O) is preferably 0.5% to 20%, more preferably 1.0% to 19%, further preferably 1.5% to 18%, further more preferably 2.0% to 17%, particularly preferably 2.5% to 16%, and most preferably 3.0% to 15.5%.

[0236] Li2O is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. The content of Li2O is preferably 0% to 15%. If the content of Li2O is 15% or less, it is less likely to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of Li2O is more preferably 0% to 8%, further preferably 0% to 7%, further more preferably 0% to 6%, and most preferably 0% to 5%.

[0237] Na2O is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. The content of Na2O is preferably 0% to 15%. If the content of Na2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of Na2O is more preferably 0.5% to 14%, further preferably 1% to 13%, further more preferably 2% to 13%, and most preferably 3% to 13%.

[0238] K2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of K2O is preferably 0% to 20%. If the content of K2O is 20% or less, the glass is less likely to become unstable, so it is preferred. The content of K2O is more preferably 0.5% to 19%, further preferably 1% to 18%, further more preferably 2% to 17%, and most preferably 3% to 16%.

[0239] Rb2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of Rb2O is preferably 0% to 15%. If the content of Rb2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of Rb2O is more preferably 0.5% to 14%, further preferably 1% to 13%, further more preferably 2% to 13%, and most preferably 3% to 13%.

[0240] Cs2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. As the content of Cs2O, it is preferably 0% to 15%. If the content of Cs2O is 15% or less, the glass is not easy to become unstable, so it is preferred. The content of Cs2O is more preferably 0.5% to 14%, further preferably 1% to 13%, further more preferably 2% to 13%, and most preferably 3% to 13%.

[0241] In addition, among the alkali metal components represented by R2O, by adding two or more of each component simultaneously, a mixed alkali effect is generated in the glass, R + The mobility of ions is reduced. As a result, when the glass comes into contact with water, the H + Ions and R in Glass +The hydration reaction caused by the ion exchange of ions improves 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, the total amount (ΣR2O) of R2O (wherein R2O is Li2O, Na2O, K2O, Rb2O and Cs2O) is preferably greater than 7% and less than or equal to 18%. If the total amount of R2O is greater than 7%, its effect can be fully obtained. If the total amount of R2O is less than 18%, it is not easy to cause problems such as the glass becoming unstable, the near-infrared cutoff property being reduced, and the strength of the glass being reduced, so it is preferred. Therefore, ΣR2O is preferably greater than 7% and less than or equal to 18%, more preferably 7.5% to 17%, further preferably 8% to 16%, further more preferably 8.5% to 15%, and most preferably 9% to 14%.

[0242] R'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO and ZnO) is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, increase the strength of glass, etc. The total amount of R'O (ΣR'O) is preferably 0% to 40%. If the total amount of R'O is 40% or less, it is less likely that the glass will become unstable, the near-infrared cutoff will decrease, and the strength of the glass will decrease. Therefore, it is preferred. The total amount of R'O (ΣR'O) is more preferably 0% to 35%, and further preferably 0% to 30%. The total amount of R'O (ΣR'O) is further more preferably 0% to 25%, particularly preferably 0% to 20%, and most preferably 0% to 15%.

[0243] CaO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, and increase the strength of glass. As the content of CaO, it is preferably 0% to 10%. If the content of CaO is less than 10%, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of CaO is more preferably 0% to 8%, further preferably 0% to 6%, further more preferably 0% to 5%, and most preferably 0% to 4%.

[0244] MgO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, and increase the strength of glass. The content of MgO is preferably 0% to 15%. If the content of MgO is 15% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of MgO is more preferably 0% to 13%, further preferably 0% to 10%, further more preferably 0% to 9%, and most preferably 0% to 8%.

[0245] BaO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. As the content of BaO, it is preferably 0% to 40%. If the content of BaO is 40% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of BaO is more preferably 0% to 30%, further preferably 0% to 20%, further more preferably 0% to 10%, and most preferably 0% to 5%.

[0246] SrO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. As the content of SrO, it is preferably 0% to 10%. If the content of SrO is 10% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of SrO is more preferably 0% to 8%, further preferably 0% to 7%, and most preferably 0% to 6%.

[0247] ZnO has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of ZnO is preferably 0% to 15%. If the content of ZnO is 15% or less, it is not easy to cause problems such as glass becoming unstable, glass solubility deteriorating, and near-infrared cutoff properties decreasing, so it is preferred. The content of ZnO is more preferably 0% to 13%, further preferably 0% to 10%, further more preferably 0% to 9%, and most preferably 0% to 8%.

[0248] CuO is a component for improving near-infrared cutoff. As the content of CuO, it is preferably 0.5% to 40%. If the content of CuO is 0.5% or more, its effect can be fully obtained. In addition, if the content of CuO is 40% or less, it is not easy to produce problems such as devitrification in the glass and reduced transmittance of light in the visible light region, so it is preferred. The content of CuO is more preferably 1.0% to 35%, further preferably 1.5% to 30%, further more preferably 2.0% to 25%, and most preferably 2.5% to 20%.

[0249] In the phosphate glass of the present embodiment, F may be contained in a range of 10% or less in order to improve weather resistance. If the content of F is 10% or less, it is less likely to cause problems such as reduced near-infrared cutoff properties and generation of devitrified foreign matter in the glass, and therefore, it is preferred. The content of F is more preferably 9% or less, further preferably 8% or less, further more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0250] In order to stabilize the glass, B2O3 may be contained within a range of 10% or less. If the content of B2O3 is 10% or less, it is not easy to produce problems such as poor weather resistance of the glass and reduced near-infrared cutoff, so it is preferred. The content of B2O3 is more preferably 9% or less, further preferably 8% or less, further more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0251] In this embodiment, in order to improve the weather resistance of the phosphate glass, SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, MoO3, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 may be contained within a range of 5% or less. If the content of these components is 5% or less, it is not easy to cause problems such as devitrification foreign matter in the glass and reduction of near-infrared cutoff properties, so it is preferred. The content of these components is preferably 4% or less, more preferably 3% or less, further preferably 2% or less, and further more preferably 1% or less.

[0252] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO are all components that reduce the transmittance of light in the visible light region by being present in phosphate glass. Therefore, it is preferred that these components are not substantially contained in the glass.

[0253] In the present invention, “substantially containing no specific component” means that the specific component is not intentionally added, and does not exclude the inclusion of the specific component to the extent that the specific component is not inevitably mixed from the raw materials, etc. and does not affect the desired properties.

[0254] From the viewpoint of reducing the height of the camera module, the thickness of the phosphate glass is preferably 0.5 mm or less, more preferably 0.3 mm or less, and from the viewpoint of maintaining the strength of the device, the thickness of the phosphate glass is preferably 0.1 mm or more, more preferably 0.15 mm or more.

[0255] Phosphate glass can be produced, for example, by the following method.

[0256] First, the raw materials are weighed and mixed in such a manner that the composition is within the above range (mixing step). The raw material mixture is placed in a platinum crucible and heated and melted in an electric furnace at a temperature of 700°C to 1400°C (melting step). After being fully stirred and clarified, it is poured into a mold, cut, and ground to form a flat plate of a specified thickness (forming step).

[0257] In the melting step of the manufacturing method, the maximum temperature of the glass during the glass melting is preferably adjusted to 1400° C. or less. If the maximum temperature of the glass during the glass melting is higher than the above temperature, the transmittance characteristics may deteriorate. The above temperature is more preferably 1350° C. or less, further preferably 1300° C. or less, and further preferably 1250° C. or less.

[0258] If the temperature in the melting step is too low, problems such as devitrification during melting and time consumption for complete melting may occur. Therefore, the temperature is preferably 700° C. or higher, and more preferably 800° C. or higher.

[0259] <Resin film>

[0260] The resin film in the optical filter of the present invention comprises a resin and a near infrared absorbing pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin. Here, the resin refers to a resin constituting the resin film.

[0261] The resin film preferably satisfies all of the following spectral characteristics (iii-1) to (iii-3).

[0262] (iii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 85%;

[0263] (iii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%;

[0264] (iii-3) The wavelength IR50 at which the internal transmittance is 50% is within the range of 660 nm to 700 nm.

[0265] Satisfying the spectral characteristic (iii-1) means that the transmittance in the blue light region is excellent.

[0266] Internal transmittance T 450 It is more preferably 87% or more, and even more preferably 90% or more.

[0267] Satisfying the spectral characteristic (iii-2) means that the transmittance in the visible light region of 450 nm to 600 nm is excellent.

[0268] Average internal transmittance T 450-600AVE It is more preferably 93% or more, and even more preferably 95%.

[0269] By satisfying the spectral characteristic (iii-3), when used in combination with the above-mentioned phosphate glass, an optical filter can be obtained in which the incidence angle dependency of the spectral characteristic is suppressed in the range of 630 nm to 680 nm.

[0270] The wavelength IR50 is more preferably in the range of 660 nm to 690 nm, and further preferably in the range of 665 nm to 685 nm.

[0271] The resin film of the present invention contains a dye having a maximum absorption wavelength in the range of 690 nm to 800 nm, and can shield light in the near-infrared region of around 700 nm, where phosphate glass has a slightly weak light shielding property, by utilizing the absorption characteristics of the dye.

[0272] Examples of near infrared absorbing pigments include those selected from cyanine pigments, phthalocyanine pigments, At least one of the group consisting of salt pigments, naphthalocyanine pigments and diimmonium pigments can be used alone or in combination. Among them, squaric acid is preferred from the viewpoint of easily exerting the effect of the present invention. Salt pigments, anthocyanin pigments.

[0273] The near infrared absorbing pigment content in the resin film is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, relative to 100 parts by mass of the resin. When two or more compounds are combined, the above content is the total of the compounds.

[0274] The resin film may contain other pigments, for example, ultraviolet light absorbing pigments, within a range not impairing the effects of the present invention.

[0275] Examples of ultraviolet light absorbing pigments include: Azoles, merocyanines, anthocyanines, naphthalimide pigments, Oxadiazole pigments, Azine pigment, Oxazolidine pigments, naphthalene dicarboxylic acid pigments, styryl pigments, anthracene pigments, cyclic carbonyl pigments, triazole pigments, etc. Among them, merocyanine pigments are particularly preferred. In addition, one may be used alone or two or more may be used in combination.

[0276] The resin is not limited as long as it is a transparent resin, and one or more transparent resins selected from polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins can be used. These resins can be used alone or in combination of two or more.

[0277] From the viewpoint of the spectral characteristics, glass transition temperature (Tg) and adhesion of the resin film, at least one resin selected from the group consisting of polyimide resins, polycarbonate resins, polyester resins and acrylic resins is preferred.

[0278] When a plurality of dyes are used, these dyes may be contained in the same resin film or may be contained in different resin films.

[0279] The resin film can be formed by dissolving or dispersing the pigment, resin or raw material components of the resin and each component as required in a solvent to prepare a coating liquid, applying the coating liquid on a support and drying it, and further curing it as required. The support at this time may be phosphate glass used in the present filter, or a peelable support used only when forming the resin film. In addition, the solvent can be any dispersion medium that can be stably dispersed or a solvent that can dissolve.

[0280] In addition, in order to improve the voids caused by tiny bubbles, the depressions caused by the attachment of foreign matter, the shrinkage holes in the drying process, etc., the coating liquid may contain a surfactant. In addition, in the coating of the coating liquid, for example, a dip coating method, a cast coating method or a spin coating method may be used. The above-mentioned coating liquid is applied to a support and then dried to form a resin film. In addition, in the case where the coating liquid contains a raw material component of a transparent resin, a curing treatment such as heat curing or photocuring is further performed.

[0281] The resin film can also be produced in a film shape by extrusion molding. The obtained film-shaped resin film is laminated on phosphate glass and integrated by thermocompression bonding or the like, thereby producing a substrate.

[0282] The optical filter may have one layer of resin film or two or more layers of resin film. When having two or more layers of resin film, each layer may have the same structure or different structures.

[0283] From the perspective of the in-plane film thickness distribution and appearance quality of the coated substrate, the thickness of the resin film is preferably 10 μm or less, more preferably 5 μm or less, and from the perspective of expressing the desired spectral characteristics with an appropriate pigment concentration, the thickness of the resin film is preferably 0.5 μm or more. It should be noted that when the optical filter has two or more layers of resin films, the total thickness of each resin film is preferably within the above range.

[0284] <Other>

[0285] This optical filter may have, for example, other components such as inorganic particles that control the transmission and absorption of light in a specific wavelength range, and components (layers) that generate absorption. Specific examples of inorganic particles include ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, and lanthanum boride. ITO particles and cesium tungstate particles have high transmittance for visible light and have light absorption in a wide range of infrared wavelengths greater than 1200 nm, so they can be used when shielding of infrared light is required.

[0286] As described above, the present specification discloses the following optical filters and the like.

[0287] [1] An optical filter comprising, in order, a first dielectric multilayer film, a resin film, a phosphate glass film, and a second dielectric multilayer film, wherein:

[0288] The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin.

[0289] The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices,

[0290] The second dielectric multilayer film includes at least one H2 layer, the H2 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5.

[0291] When the layer closest to the phosphate glass in the H2 layer is set as the first H2 layer,

[0292] A first M2 layer is included between the first H2 layer and the phosphate glass, the first M2 layer being composed of a single layer satisfying a QWOT of 1.2 or more and 1.8 or less or a plurality of layers satisfying a total QWOT of 1.2 or more and 1.8 or less,

[0293] The filter satisfies all of the following spectral characteristics (i-1) to (i-4):

[0294] (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%;

[0295] (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%;

[0296] (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%;

[0297] (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

[0298] [2] An optical filter comprising, in order, a first dielectric multilayer film, a resin film, a phosphate glass film, and a second dielectric multilayer film, wherein:

[0299] The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin.

[0300] The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices,

[0301] The first dielectric multilayer film includes at least one H1 layer, the H1 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5.

[0302] When the layer closest to the resin film in the H1 layer is set as the first H1 layer,

[0303] A first M1 layer is included between the first H1 layer and the resin film, the first M1 layer being composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.8,

[0304] The filter satisfies all of the following spectral characteristics (i-1) to (i-4):

[0305] (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%;

[0306] (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%;

[0307] (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%;

[0308] (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

[0309] [3] The optical filter as described in [1], wherein the optical filter further satisfies the following spectral characteristics (i-5) to (i-8):

[0310] (i-5) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 of the wavelength 750nm to 1000nm 750-1000(5deg)AVE Less than 3%;

[0311] (i-6) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0312] (i-7) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0313] (i-8) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0314] [4] The optical filter as described in any one of [1] to [3], wherein the optical filter further satisfies the following spectral characteristics (i-9) to (i-12):

[0315] (i-9) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(0deg)AVE Below 7%;

[0316] (i-10) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(50deg)AVE Below 7%;

[0317] (i-11) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the wavelength IR30 when the transmittance is 30% (0deg) In the wavelength range of 630nm to 680nm;

[0318] (i-12) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the wavelength IR30 when the transmittance is 30% (50deg) In the wavelength range of 630nm ~ 680nm.

[0319] [5] The optical filter as described in any one of [1], [3] and [4], characterized in that the first dielectric multilayer film includes at least one H1 layer, the H1 layer has a refractive index of not less than 1.8 and not more than 2.5 and a QWOT of not less than 1.1 and not more than 3.5,

[0320] When the layer closest to the resin film in the H1 layer is set as the first H1 layer,

[0321] A first M1 layer is included between the first H1 layer and the resin film, and the first M1 layer is composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.8.

[0322] [6] The optical filter described in [2] is characterized in that the second dielectric multilayer film includes at least one H2 layer, the H2 layer has a refractive index of not less than 1.8 and not more than 2.5 and a QWOT of not less than 1.1 and not more than 3.5,

[0323] When the layer closest to the phosphate glass in the H2 layer is set as the first H2 layer,

[0324] A first M2 layer is included between the first H2 layer and the phosphate glass, and the first M2 layer is composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.8.

[0325] [7] The optical filter as described in [5], wherein the optical filter further satisfies the following spectral characteristics (i-13) to (i-16):

[0326] (i-13) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(5deg)AVE Less than 3%;

[0327] (i-14) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%;

[0328] (i-15) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%;

[0329] (i-16) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

[0330] [8] The optical filter as described in any one of [1] to [7], wherein the optical filter further satisfies the following spectral characteristics (i-17) to (i-20):

[0331] (i-17) The average transmittance T 450-550(0deg)AVE With the average transmittance T 450-550(50deg)AVE The absolute value of the difference is less than 3.5%;

[0332] (i-18) The average transmittance T 750-1000(0deg)AVE With the average transmittance T 750-1000(50deg)AVE The absolute value of the difference is less than 1.5%;

[0333] (i-19) Average transmittance T at wavelengths of 1000 nm to 1200 nm in the spectral transmittance curve under the condition of an incident angle of 0 degrees 1000-1200(0deg)AVE The average transmittance T of the wavelength 1000nm to 1200nm in the spectral transmittance curve under the condition of an incident angle of 50 degrees 1000-1200(50deg)AVE The absolute value of the difference is less than 1.5%;

[0334] (i-20) The wavelength IR30 when the transmittance is 30% in the spectral transmittance curve under the condition of an incident angle of 0 degrees (0deg) The wavelength IR30 when the transmittance is 30% in the spectral transmittance curve under the condition of an incident angle of 50 degrees (50deg) The absolute value of the difference is less than 15 nm.

[0335] [9] The optical filter as described in any one of [1] to [8], wherein the optical filter further satisfies the following spectral characteristic (i-21):

[0336] (i-21) When the second dielectric multilayer film side is taken as the incident direction, within the wavelength range of 750 nm to 1000 nm, the average value of the absorption loss amount defined below is 95% or more,

[0337] (Absorption loss) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectivity at an incident angle of 5 degrees).

[0338]

[10] The optical filter as described in any one of [1] to [9], wherein the optical filter further satisfies the following spectral characteristic (i-22):

[0339] (i-22) When the second dielectric multilayer film side is taken as the incident direction, within the wavelength range of 750nm to 1000nm, the minimum value of the absorption loss amount defined below is greater than 90%,

[0340] (Absorption loss) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectivity at an incident angle of 5 degrees).

[0341]

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

[10] , wherein the optical filter further satisfies the following spectral characteristic (i-23):

[0342] (i-23) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R2 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R2 n(5deg) The number of n that is less than 1% is 200 or more.

[0343]

[12] The optical filter as described in any one of [5] to

[11] , wherein the optical filter further satisfies the following spectral characteristic (i-24):

[0344] (i-24) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R1 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R1 n(5deg) The number of n that is less than 1% is 150 or more.

[0345]

[13] The optical filter according to any one of [1], [3] to [5], and [7] to

[12] , wherein

[0346] The second dielectric multilayer film includes two or more H2 layers.

[0347] When the second layer in the H2 layer that is closest to the phosphate glass is set as the second H2 layer,

[0348] A second M2 layer is included between the first H2 layer and the second H2 layer, and the second M2 layer is composed of a single layer satisfying a QWOT of 1.2 to 2.1 or a plurality of layers satisfying a total QWOT of 1.2 to 2.1.

[0349]

[14] An optical filter as described in

[13] , wherein the second dielectric multilayer film includes a third M2 layer between the first H2 layer and the second M2 layer, and the third M2 layer is composed of a single layer satisfying a QWOT of greater than 1.2 and less than 2.1 or a plurality of layers satisfying a total QWOT of greater than 1.2 and less than 2.1.

[0350]

[15] The optical filter as described in any one of [1] to

[14] , wherein the phosphate glass satisfies all of the following spectral characteristics (ii-1) to (ii-5):

[0351] (ii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 92%;

[0352] (ii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%;

[0353] (ii-3) the wavelength IR50 at which the internal transmittance is 50% is within the wavelength range of 625 nm to 650 nm;

[0354] (ii-4) Average internal transmittance T at wavelengths of 750 nm to 1000 nm 750-1000AVE Less than 2.5%;

[0355] (ii-5) Average internal transmittance T at wavelengths of 1000 nm to 1200 nm 1000-1200AVE Below 7%.

[0356]

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

[15] , wherein the resin film satisfies all of the following spectral characteristics (iii-1) to (iii-3):

[0357] (iii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 85%;

[0358] (iii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%;

[0359] (iii-3) The wavelength IR50 at which the internal transmittance is 50% is within the range of 660 nm to 700 nm.

[0360]

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

[16] , wherein the phosphate glass has the following composition, which comprises, in terms of mass percentage based on oxides:

[0361] 40% to 80% P2O5,

[0362] 0.5%~20% Al2O3,

[0363] 0.5% to 20% ΣR2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O and Cs2O, and ΣR2O is the total amount of R2O),

[0364] 0% to 40% ΣR'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO and ZnO, and ΣR'O is the total amount of R'O),

[0365] 0.5%~40% CuO.

[0366]

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

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

[0367] Example

[0368] Next, the present invention will be described in more detail with reference to examples.

[0369] For the measurement of each spectral characteristic, an ultraviolet-visible spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation) was used.

[0370] In addition, when the incident angle is not particularly clearly stated, the spectral characteristics are values ​​measured under the condition of an incident angle of 0° (a direction perpendicular to the main surface of the filter).

[0371] The pigments used in each example are as follows.

[0372] Compound 1 (squaric acid Salt compound): synthesized based on International Publication No. 2017 / 135359.

[0373] Compound 2 (merocyanine compound): synthesized based on the specification of German Patent Gazette No. 10109243.

[0374] Compound 3 (cyanine compound): synthesized based on the method described in Dyes and Pigments, 73, 344-352 (2007).

[0375] Compound 4 (squaric acid Salt compound): synthesized according to the method described in JP-A-2017-110209.

[0376]

[0377] <Spectral characteristics of pigments in resin>

[0378] A polyimide resin (Mitsubishi Gas Chemical Co., Ltd., "C3G30G" (trade name), refractive index 1.59) was dissolved in γ-butyrolactone (GBL):cyclohexanone=1:1 (mass ratio) to prepare a polyimide resin solution having a resin concentration of 8.5 mass %.

[0379] The pigments of the above compounds 1 to 4 were added to the above resin solution at a concentration of 7.5 parts by mass of each pigment relative to 100 parts by mass of the resin, and stirred and dissolved at 50° C. for 2 hours to obtain a coating solution. The obtained coating solution was applied to an alkali glass (manufactured by Schott, D263 glass, with a thickness of 0.2 mm) by spin coating to form a coating film with a film thickness of about 1.0 μm.

[0380] The spectral transmittance curve of the obtained coating film in the wavelength range of 350 nm to 1200 nm was measured using an ultraviolet-visible spectrophotometer.

[0381] The spectral characteristics of each of the above compounds 1 to 4 in the polyimide resin are shown in the following table. Note that the spectral characteristics shown in the following table were evaluated using internal transmittance in order to avoid the influence of reflection at the air interface and the glass interface.

[0382] [Table 1]

[0383]

[0384] <Example 1-1 and Example 1-2: Spectral characteristics of resin film>

[0385] Any one of the pigments in compounds 1 to 4 was mixed with the polyimide resin solution (Mitsubishi Gas Chemical Co., Ltd., C3G30G) prepared in the same manner as when calculating the spectral characteristics of the above compounds at the concentrations described in the table below, stirred and dissolved at 50° C. for 2 hours to obtain a resin solution. The obtained resin solution was applied to an alkali glass (Schott Co., Ltd., D263 glass, 0.2 mm thick) by spin coating to form a resin film with a film thickness of 1.0 μm.

[0386] The spectral transmittance curve of the obtained resin film in the wavelength range of 350 nm to 1200 nm was measured using an ultraviolet-visible spectrophotometer.

[0387] The obtained spectral characteristics are shown in the following table. It should be noted that the spectral characteristics shown in the following table were evaluated using internal transmittance in order to avoid the influence of reflection at the air interface and the glass interface.

[0388] It should be noted that Examples 1-1 and 1-2 are reference examples.

[0389] [Table 2]

[0390]

[0391] <Spectral characteristics of glass>

[0392] Phosphate glass 1 and phosphate glass 2 were prepared as phosphate glasses according to the following operation procedures.

[0393] The raw materials were weighed and mixed in a manner to form the composition (mass % of oxide basis) shown in the following table, placed in a crucible with an internal volume of about 400cc, and melted for 2 hours in an atmospheric atmosphere. Then, the mixture was clarified and stirred, and poured into a rectangular mold of 100mm in length × 80mm in width × 20mm in height preheated to about 300°C to about 500°C, and then slowly cooled at about 1°C / min to form a plate of 40mm in length × 30mm in width and a thickness of the value shown in Table 4, and both sides were optically polished to obtain a plate-shaped glass.

[0394] In addition, NF50T manufactured by AGC Corporation was prepared as fluorophosphate glass 1 and fluorophosphate glass 2. The thicknesses of fluorophosphate glass 1 and fluorophosphate glass 2 are shown in Table 4, respectively.

[0395] [Table 3]

[0396]

[0397] For each glass, a spectral transmittance curve in a wavelength range of 350 nm to 1200 nm was measured using an ultraviolet-visible spectrophotometer.

[0398] The obtained spectral characteristics are shown in the table below. It should be noted that, for the spectral characteristics shown in the table below, internal transmittance was used to evaluate in order to avoid the influence of reflection at the air interface and the glass interface. The obtained results are shown in the table below.

[0399] In addition, the haze of each glass was determined based on JIS K7136 using an automatic haze meter (manufactured by Tokyo Denshoku Co., Ltd., model: TC-HIIIDPK).

[0400] In addition, the spectral transmittance curves of phosphate glass 1 and fluorophosphate glass 1 are shown in Figure 5 middle.

[0401] [Table 4]

[0402]

[0403] From the above results, it can be seen that phosphate glass 1 and phosphate glass 2 having a specific glass composition have a high transmittance in the visible light region and a high light shielding property in the near-infrared light region compared to fluorophosphate glass 1 and fluorophosphate glass 2. In addition, phosphate glass 1 and phosphate glass 2 having a specific glass composition have a low haze.

[0404] On the other hand, although fluorophosphate glass 1 and fluorophosphate glass 2 maintain high visible light transmittance, they have poor infrared light shielding properties. In addition, in order to improve light shielding properties, the thickness of the glass is increased, resulting in that the wavelength IR50 is on the short wavelength side and cannot meet the desired spectral characteristics.

[0405] <Example 2-1 to Example 2-8: Configuration of filter>

[0406] [Example 2-1]

[0407] A second dielectric multilayer film having a total of 8 layers was formed by vapor deposition on one main surface of the above-mentioned phosphate glass 1 (thickness: 0.28 mm) in such a manner that each layer had a film material and film thickness (nm) as shown in the following table. Hereinafter, the dielectric multilayer film having the structure of Table 5 is referred to as "dielectric multilayer film 1".

[0408] [Table 5]

[0409]

[0410] A resin film was formed on the main surface of the phosphate glass 1 by the same method as in Example 1-1. Then, a dielectric multilayer film 1 was formed as a first dielectric multilayer film on the surface of the resin film by vapor deposition, thereby obtaining an optical filter of Example 2-1. The configuration of the optical filter of Example 2-1 is shown in Tables 10 and 11. Figure 2 middle.

[0411] It should be noted that, when the dielectric multilayer film 1 is formed as the second dielectric multilayer film, the H layer / M layer column in Table 5 can be considered as the H2 layer / M2 layer, and when the dielectric multilayer film 1 is formed as the first dielectric multilayer film, the H layer / M layer column in Table 5 can be considered as the H1 layer / M1 layer. The same applies to the following tables.

[0412] [Example 2-2]

[0413] A filter was produced in the same manner as in Example 2-1 except that dielectric multilayer films having the structures shown in the following table were formed as the first dielectric multilayer film and the second dielectric multilayer film. Hereinafter, the dielectric multilayer film having the structure shown in Table 6 is referred to as "dielectric multilayer film 2". The structure of the filter of Example 2-2 is shown in Tables 10 and 11. Figure 3 middle.

[0414] [Table 6]

[0415]

[0416] [Example 2-3]

[0417] A filter was produced in the same manner as in Example 2-1 except that dielectric multilayer films having the structures shown in the following table were formed as the first dielectric multilayer film and the second dielectric multilayer film. Hereinafter, the dielectric multilayer film having the structure shown in Table 7 is referred to as "dielectric multilayer film 3". The structures of the filters of Example 2-3 are shown in Tables 10 and 11. Figure 4 middle.

[0418] [Table 7]

[0419]

[0420] [Example 2-4]

[0421] A filter was produced in the same manner as in Example 2-1 except that a dielectric multilayer film having a structure shown in the following table was formed as the first dielectric multilayer film. Hereinafter, the dielectric multilayer film having a structure shown in Table 8 is referred to as "dielectric multilayer film 4". The structure of the filter of Example 2-4 is shown in Table 10.

[0422] [Table 8]

[0423]

[0424] [Example 2-5]

[0425] An optical filter was produced in the same manner as in Example 2-4 except that the dielectric multilayer film 4 was formed as the second dielectric multilayer film.

[0426] [Example 2-6]

[0427] A filter was produced in the same manner as in Example 2-4 except that fluorophosphate glass 1 was used as phosphate glass, the resin film of Example 1-2 was formed as the resin film, and a dielectric multilayer film having a structure shown in the following table was formed as the second dielectric multilayer film. Hereinafter, the dielectric multilayer film having a structure shown in Table 9 is referred to as "dielectric multilayer film 5". The structure of the filter of Example 2-6 is shown in Table 11.

[0428] [Table 9]

[0429]

[0430] [Example 2-7]

[0431] An optical filter was produced in the same manner as in Example 2-6 except that the dielectric multilayer film 1 was formed as the first dielectric multilayer film.

[0432] [Example 2-8]

[0433] The optical filter of Example 2-8 was prepared in the same manner as in Example 2-1 except that fluorophosphate glass was used as phosphate glass.

[0434] <Examples 2-1 to 2-8: Spectral characteristics of filters>

[0435] For the optical filters of Examples 2-1 to 2-8, the spectral transmittance curves at the conditions of incident angles of 0 and 50 degrees and the spectral reflectance curves at the conditions of incident angles of 5 and 50 degrees in the wavelength range of 350 nm to 1200 nm were measured using an ultraviolet-visible spectrophotometer. It should be noted that in the measurement of the spectral reflectance curves, the case where the second dielectric multilayer film side is the incident direction is represented as the "front surface", and the case where the first dielectric multilayer film side is the incident direction is represented as the "back surface".

[0436] The characteristics shown in the following table were calculated from the obtained spectral characteristic data.

[0437] In addition, the spectral transmittance curves (incident angles 0 and 50 degrees) of the filters of Examples 2-1, 2-4, 2-5, and 2-6 and the reflectance curves (incident angles 5 and 50 degrees) when the second dielectric multilayer film side is the incident direction are shown in FIG. Figure 6 to Figure 13 middle.

[0438] It should be noted that Examples 2-1 to 2-4 are embodiments, and Examples 2-5 to 2-8 are comparative examples.

[0439] [Table 10]

[0440]

[0441] [Table 11]

[0442]

[0443] From the above results, it can be seen that compared with Examples 2-5 to 2-8 as comparative examples, the filters of Examples 2-1 to 2-4 as embodiments are filters that have high transmittance in the visible light region and high shielding properties in the near-infrared light region, and the change in visible light transmittance is small even at high incident angles, thereby suppressing the generation of ripples. In addition, the reflectivity is small on all incident surfaces, thereby also suppressing the generation of stray light.

[0444] On the other hand, the optical filters of Example 2-5 as comparative examples have large reflection characteristics on all incident surfaces.

[0445] In addition, the optical filter of Example 2-6 as a comparative example has large reflection characteristics on all incident surfaces, poor light shielding properties in the near-infrared region, and a large absorption loss.

[0446] In addition, the optical filter of Example 2-7 as a comparative example has a large reflection characteristic when incident light is incident on a glass surface, is poor in light shielding properties in the near-infrared region, and has a large absorption loss.

[0447] In addition, the optical filter of Example 2-8 as a comparative example was inferior in light shielding property in the near-infrared region.

[0448] The present invention is described in detail with reference to specific embodiments, but various changes and modifications can be made without departing from the spirit and scope of the present invention, which is obvious to those skilled in the art. This application is based on Japanese patent application (Japanese patent application 2022-138361) filed on August 31, 2022, and its contents are incorporated into this application by reference.

[0449] Description of symbols

[0450] 1B filter

[0451] 11 Phosphate glass

[0452] 12 Resin film

[0453] 20A Second dielectric multilayer film

[0454] 20B First dielectric multilayer film

Claims

1. A filter, comprising a first dielectric multilayer film, a resin film, a phosphate glass and a second dielectric multilayer film in sequence, wherein: The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin. The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices, The second dielectric multilayer film includes at least one H2 layer, the H2 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.

5. When the layer closest to the phosphate glass in the H2 layer is set as the first H2 layer, A first M2 layer is included between the first H2 layer and the phosphate glass, the first M2 layer being composed of a single layer satisfying a QWOT of 1.2 or more and 1.8 or less or a plurality of layers satisfying a total QWOT of 1.2 or more and 1.8 or less, The filter satisfies all of the following spectral characteristics (i-1) to (i-4): (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%; (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%; (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%; (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

2. A filter, comprising a first dielectric multilayer film, a resin film, a phosphate glass and a second dielectric multilayer film in sequence, wherein: The resin film includes a resin and a pigment having a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin. The first dielectric multilayer film and the second dielectric multilayer film each include a plurality of layers with different refractive indices, The first dielectric multilayer film includes at least one H1 layer, the H1 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.

5. When the layer closest to the resin film in the H1 layer is set as the first H1 layer, A first M1 layer is included between the first H1 layer and the resin film, the first M1 layer being composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.8, The filter satisfies all of the following spectral characteristics (i-1) to (i-4): (i-1) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(0deg)AVE More than 85%; (i-2) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 450nm to 550nm 450-550(50deg)AVE More than 85%; (i-3) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T 750-1000(0deg)AVE Less than 2.5%; (i-4) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T 750-1000(50deg)AVE Below 2.5%.

3. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-5) to (i-8): (i-5) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 at wavelengths of 750nm to 1000nm is 750-1000(5deg)AVE Less than 3%; (i-6) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R2 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%; (i-7) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%; (i-8) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R2 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

4. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-9) to (i-12): (i-9) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(0deg)AVE Below 7%; (i-10) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the average transmittance T of the wavelength 1000nm to 1200nm 1000-1200(50deg)AVE Below 7%; (i-11) In the spectral transmittance curve under the condition of an incident angle of 0 degrees, the wavelength IR30 when the transmittance is 30% (0deg) In the wavelength range of 630nm to 680nm; (i-12) In the spectral transmittance curve under the condition of an incident angle of 50 degrees, the wavelength IR30 when the transmittance is 30% (50deg) In the wavelength range of 630nm ~ 680nm.

5. The optical filter according to claim 1, wherein: The first dielectric multilayer film includes at least one H1 layer, the H1 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.

5. When the layer closest to the resin film in the H1 layer is set as the first H1 layer, A first M1 layer is included between the first H1 layer and the resin film, and the first M1 layer is composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.

8.

6. The optical filter according to claim 2, characterized in that: The second dielectric multilayer film includes at least one H2 layer, the H2 layer has a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.

5. When the layer closest to the phosphate glass in the H2 layer is set as the first H2 layer, A first M2 layer is included between the first H2 layer and the phosphate glass, and the first M2 layer is composed of a single layer satisfying a QWOT of 1.2 to 1.8 or a plurality of layers satisfying a total QWOT of 1.2 to 1.

8.

7. The optical filter according to claim 5, wherein: The filter also satisfies the following spectral characteristics (i-13) to (i-16): (i-13) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at wavelengths of 750nm to 1000nm is 750-1000(5deg)AVE Less than 3%; (i-14) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(5deg)AVE Less than 3%; (i-15) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 750nm to 1000nm is 750-1000(50deg)AVE Less than 5%; (i-16) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 50 degrees, the average reflectance R1 at a wavelength of 450nm to 600nm is 450-600(50deg)AVE Less than 5%.

8. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-17) to (i-20): (i-17) The average transmittance T 450-550(0deg)AVE With the average transmittance T 450-550(50deg)AVE The absolute value of the difference is less than 3.5%; (i-18) The average transmittance T 750-1000(0deg)AVE With the average transmittance T 750-1000(50deg)AVE The absolute value of the difference is less than 1.5%; (i-19) Average transmittance T at wavelengths of 1000 nm to 1200 nm in the spectral transmittance curve under the condition of an incident angle of 0 degrees 1000-1200(0deg)AVE The average transmittance T of the wavelength 1000nm to 1200nm in the spectral transmittance curve under the condition of an incident angle of 50 degrees 1000-1200(50deg)AVE The absolute value of the difference is less than 1.5%; (i-20) The wavelength IR30 when the transmittance is 30% in the spectral transmittance curve under the condition of an incident angle of 0 degrees (0deg) The wavelength IR30 when the transmittance is 30% in the spectral transmittance curve under the condition of an incident angle of 50 degrees (50deg) The absolute value of the difference is less than 15 nm.

9. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-21): (i-21) When the second dielectric multilayer film side is taken as the incident direction, within the wavelength range of 750 nm to 1000 nm, the average value of the absorption loss amount defined below is 95% or more, (Absorption loss) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectivity at an incident angle of 5 degrees).

10. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-22): (i-22) When the second dielectric multilayer film side is taken as the incident direction, within the wavelength range of 750nm to 1000nm, the minimum value of the absorption loss amount defined below is greater than 90%, (Absorption loss) [%] = 100 - (transmittance at an incident angle of 5 degrees) - (reflectivity at an incident angle of 5 degrees).

11. The optical filter according to claim 1, wherein: The filter also satisfies the following spectral characteristics (i-23): (i-23) When the second dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R2 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R2 n(5deg) The number of n that is less than 1% is 200 or more.

12. The optical filter according to claim 4, wherein: The filter also satisfies the following spectral characteristics (i-24): (i-24) When the first dielectric multilayer film side is taken as the incident direction, in the spectral reflectance curve under the condition of an incident angle of 5 degrees, the reflectance R1 of each wavelength is read at an interval of 1 nm from a wavelength of 750 nm to a wavelength of 1000 nm. n(5deg) (n: arbitrary integer), the reflectivity R1 n(5deg) The number of n that is less than 1% is 150 or more.

13. The optical filter according to claim 1, wherein: The second dielectric multilayer film includes two or more H2 layers. When the second layer in the H2 layer that is closest to the phosphate glass is set as the second H2 layer, A second M2 layer is included between the first H2 layer and the second H2 layer, and the second M2 layer is composed of a single layer satisfying a QWOT of 1.2 to 2.1 or a plurality of layers satisfying a total QWOT of 1.2 to 2.

1.

14. The optical filter according to claim 13, wherein: The second dielectric multilayer film includes a third M2 layer between the first H2 layer and the second M2 layer, and the third M2 layer is composed of a single layer satisfying QWOT of 1.2 to 2.1 or a plurality of layers satisfying a total QWOT of 1.2 to 2.

1.

15. The optical filter according to claim 1, wherein: The phosphate glass satisfies all of the following spectral characteristics (ii-1) to (ii-5): (ii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 92%; (ii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%; (ii-3) the wavelength IR50 at which the internal transmittance is 50% is within the wavelength range of 625 nm to 650 nm; (ii-4) Average internal transmittance T at wavelengths of 750 nm to 1000 nm 750-1000AVE Less than 2.5%; (ii-5) Average internal transmittance T at wavelengths of 1000 nm to 1200 nm 1000-1200AVE Below 7%.

16. The optical filter according to claim 1, wherein: The resin film satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) Internal transmittance T at a wavelength of 450 nm 450 More than 85%; (iii-2) Average internal transmittance T at wavelengths of 450 nm to 600 nm 450-600AVE More than 90%; (iii-3) The wavelength IR50 at which the internal transmittance is 50% is within the range of 660 nm to 700 nm.

17. The optical filter according to claim 1, wherein: The phosphate glass has the following composition, which is calculated by mass percentage based on oxides: 40% to 80% P2O5, 0.5%~20% Al2O3, 0.5% to 20% ΣR2O (wherein R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O and Cs2O, and ΣR2O is the total amount of R2O), 0% to 40% ΣR'O (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO and ZnO, and ΣR'O is the total amount of R'O), 0.5%~40% CuO.

18. The optical filter according to claim 1, wherein: The resin film has a thickness of 10 μm or less.

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