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JP-7856139-B2 - Optical filter

JP7856139B2JP 7856139 B2JP7856139 B2JP 7856139B2JP-7856139-B2

Inventors

  • 塩野 和彦
  • 遠藤 清和
  • 長田 崇

Assignees

  • ＡＧＣ株式会社

Dates

Publication Date
20260511
Application Date
20230221
Priority Date
20220302

Claims (17)

  1. An optical filter comprising a substrate, a dielectric multilayer film (I) on one main surface side of the substrate, and a dielectric multilayer film (II) on the other main surface side of the substrate, The substrate comprises near-infrared absorbing glass and a resin film. The resin film comprises a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) , (i-4), (i-5), and (i-7) . (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 440-600 (0 deg) AVE for wavelengths of 440-600 nm is 86% or higher. ( i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 800-1200 (0 deg) AVE at wavelengths of 800-1200 nm is 3% or less. (i-5) When the dielectric multilayer film (I) side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI 440-600 (5 deg) AVE at wavelengths of 440-600 nm is 4% or less. ( i-7) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII 700-800 (40deg) AVE at wavelengths of 700-800 nm in the spectral reflectance curve at an incident angle of 40 degrees is 5.5% or less.
  2. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-2). (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR50 is such that the transmittance is 50% in the range of wavelengths 550 to 750 nm. (0 deg) T And, in the spectral transmittance curve at an incident angle of 40 degrees, the wavelength IR50 has a transmittance of 50% in the range of wavelengths 550 to 750 nm. (40 deg) T The absolute value of the difference is 6 nm or less.
  3. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-3). (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 700 to 800 nm. 700-800(0deg)AVE less than 1%
  4. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-6). (i-6) When the dielectric multilayer film (I) side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI at wavelengths of 800 to 1200 nm 800-1200 (5deg) AVE over 95%
  5. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-8). (i-8) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 800 to 1200 nm. 800-1200 (40deg) AVE over 10%
  6. In the spectral transmittance curve at an incident angle of 40 degrees, the average transmittance T for wavelengths of 440-600 nm is shown. 440-600(40deg)AVE The optical filter according to claim 1, wherein the ratio is 85.6% or more.
  7. In the spectral transmittance curve at an incident angle of 40 degrees, the average transmittance T for wavelengths of 800 to 1200 nm is shown. 800-1200 (40deg) AVE The optical filter according to claim 1, wherein the content is 2.6% or less.
  8. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII 700-800 (50 deg) AVE at wavelengths of 700-800 nm in the spectral reflectance curve at an incident angle of 50 degrees is 8% or less. (i-10) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII 800-1200 (50 deg) AVE at wavelengths of 800-1200 nm in the spectral reflectance curve at an incident angle of 50 degrees is 10% or more.
  9. The optical filter according to claim 1, wherein the near-infrared absorbing glass satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Average internal transmittance T 400-600AVE at wavelengths of 400-600nm is 90% or higher. (iii-2) Average internal transmittance T 700-800AVE at wavelengths of 700-800nm is 40% or lower. (iii-3) Average internal transmittance T 800-1200AVE at wavelengths of 800-1200nm is 40% or lower.
  10. The optical filter according to claim 1, wherein the dielectric multilayer film (II) is laminated on the resin film.
  11. The optical filter according to claim 1, wherein the dielectric multilayer film (II) satisfies all of the following spectral characteristics (v-II-1) to (v-II-2). (v-II-1) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII 700-800 (5deg) MAX at wavelengths of 700-800 nm is 8% or less. (v-II-2) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII 700-800 (5deg) AVE at wavelengths of 700-800 nm is 6% or less.
  12. The optical filter according to claim 1, wherein the dielectric multilayer film (II) satisfies all of the following spectral characteristics (v-II-3) to (v-II-5). (v-II-3) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII 700-800 (5deg) MAX at wavelengths of 700-800 nm is 7.5% or less. (v-II-4) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII 700-800 (5deg) AVE at wavelengths of 700-800 nm is 5.5% or less. (v-II-5) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII 800-1200 (5deg) AVE at wavelengths of 800-1200 nm is 20% or more.
  13. The optical filter according to claim 1, wherein the dielectric multilayer film (II) further satisfies the following spectral characteristics (v-II-6). (v-II-6) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII 440-600 (5deg) AVE at wavelengths of 440-600 nm is 6% or less.
  14. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-12). (i-12) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength at which the transmittance is 50% in the range of 550 to 750 nm is defined as IR50 (0 deg)T . When the dielectric multilayer film (I) side is considered the incident direction, and the spectral reflectance curve at an incident angle of 5 degrees shows that the wavelength at which the reflectance is 50% in the range of 550 to 750 nm is defined as IR50 (5 deg)R , The absolute value of the difference between IR50 (0 deg) T and IR50 (5 deg) R is 85 nm or greater.
  15. The optical filter according to claim 1, wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-3). (iv-1) The average internal transmittance T 440-600AVE at wavelengths of 440-600 nm is 90% or more. (iv-2) The average internal transmittance T 700-800AVE at wavelengths of 700-800 nm is 50% or less. (iv-3) In the spectral transmittance curve at wavelengths of 600-800 nm, when the shortest wavelength at which the internal transmittance is 50% is defined as IR50 (S) and the longest wavelength as IR50 (L) , IR50 (L) - IR50 (S) ≧100nm
  16. The optical filter according to claim 1, wherein the resin film further comprises a dye (NIR2) having a maximum absorption wavelength in the resin between 680 and 870 nm, and having a different maximum absorption wavelength from the dye (NIR1).
  17. An imaging apparatus comprising an optical filter according to any one of claims 1 to 16 .

Description

This invention relates to an optical filter that transmits visible light and blocks near-infrared light. In imaging devices using solid-state image sensors, optical filters are used that transmit visible light (hereinafter also referred to as "visible light") and block near-infrared wavelength light (hereinafter also referred to as "near-infrared light") in order to reproduce colors well and obtain sharp images. Such optical filters can take various forms, such as reflective filters that alternately layer dielectric thin films with different refractive indices on one or both sides of a transparent substrate (dielectric multilayer film) and reflect the light to be blocked by utilizing light interference. Patent documents 1 and 2 describe optical filters having a dielectric multilayer film and an absorbing layer containing a dye. International Publication No. 2020/050177International Publication No. 2020/004641 Figure 1 is a schematic cross-sectional view showing an example of an optical filter according to one embodiment.Figure 2 is a schematic cross-sectional view showing another example of an optical filter according to one embodiment.Figure 3 illustrates the mechanism of repetitive reflection generation between the sensor and the optical filter.Figure 4 shows the spectral transmittance curves of the resin film of Example 1-1 and the resin film of Example 1-2.Figure 5 shows the spectral reflectance curves of the dielectric multilayer film (II) of Example 3-3 and the dielectric multilayer film (II) of Example 3-4.Figure 6 shows the spectral transmittance curves of the optical filter of Example 4-1 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side.Figure 7 shows the spectral reflectance curve of the optical filter of Example 4-1 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side.Figure 8 shows the spectral transmittance curves of the optical filter of Example 4-2 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side.Figure 9 shows the spectral reflectance curve of the optical filter of Example 4-2 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side. Embodiments of the present invention will be described below. In this specification, near-infrared absorbing dyes may be abbreviated as "NIR dyes," and ultraviolet absorbing dyes may be abbreviated as "UV dyes." In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. A dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. Furthermore, the group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas. In this specification, internal transmittance is the transmittance obtained by subtracting the effect of interfacial reflection from the measured transmittance, as shown by the formula {measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))} × 100. In this specification, the spectral transmission of a substrate and the transmission of a resin film, including cases where a dye is contained in the resin, refers to "internal transmission" even when the term "transmission" is used. On the other hand, the transmission of a dielectric multilayer film and the transmission of an optical filter having a dielectric multilayer film are measured transmission values. In this specification, for a particular wavelength range, a transmittance of, for example, 90% or more means that the transmittance does not fall below 90% across the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, for a particular wavelength range, a transmittance of, for example, 1% or less means that the transmittance does not exceed 1% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance in a particular wavelength range are the arithmetic mean of the transmittance and internal transmittance for every 1 nm in that wavelength range. The spectral characteristics can be measured using a UV-Vis spectrophotometer. In this specification, the "～" symbol used to indicate a numerical range includes both upper and lower limits. <Optical Filters> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "this filter") comprises a substrate, a dielectric multilayer film 1 laminated as the outermost layer on one main surface side of the