Optical filter and imaging apparatus
AssigneeNippon Sheet Glass Co., Ltd.
InventorsTomitaka Takagi, Katsuhide Shimmo
Life of this patent
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Abstract
An optical (1a) includes a light-absorbing layer (10). The light-absorbing layer absorbs light in at least a portion of the near-infrared region. When light with a wavelength of 300 to 1200 nm is incident on the optical filter (1a) at an incident angle of 0°, the optical filter (1a) satisfies given spectral transmittance requirements. When an average of absolute values of differences each between a value of a normalized spectral transmittance for an incident angle x° and a value of a normalized spectral transmittance for an incident angle y° in the wavelength range of W nm to V nm (W<V) is expressed as ΔTSx/yW-V, the optical filter (1a) satisfies requirements ΔTS0/40380-530≤3%, ΔTS0/40450-650≤3%, and ΔTS0/40530-750≤3%.
Claims17
An optical filter comprising:
- a light-absorbing layer that includes a light absorber for absorbing light in at least a portion of the near-infrared region, wherein
- when light with a wavelength of 300 to 1200 nm is incident on the optical filter at an incident angle of 0°, the optical filter satisfies the following requirements (1) to (9):
- (1) a spectral transmittance at a wavelength of 380 nm is 20% or less;
- (2) the spectral transmittance at a wavelength of 450 nm is 75% or more;
- (3) an average of the spectral transmittance in the wavelength range of 500 to 600 nm is 80% or more;
- (4) the spectral transmittance at a wavelength of 700 nm is 5% or less;
- (5) the spectral transmittance at a wavelength of 715 nm is 3% or less;
- (6) an average of the spectral transmittance in the wavelength range of 700 to 800 nm is 1% or less;
- (7) the maximum of the spectral transmittance in the wavelength range of 750 to 1080 nm is 1% or less;
- (8) the maximum of the spectral transmittance in the wavelength range of 1000 to 1100 nm is 2% or less;
- and
- (9) a wavelength bandwidth of a wavelength band in which the spectral transmittance in the wavelength range of 400 to 700 nm is 75% or more is 170 nm or more,
- when light with a wavelength of 300 to 1200 nm is incident on the optical filter at incident angles of x° and y° (0≤x≤30, 30≤y≤65, and x<y) and an average of absolute values of differences each between a value of a normalized spectral transmittance for the incident angle x° and a value of a normalized spectral transmittance for the incident angle y° at the same wavelength in the wavelength range of W nm to V nm (W<V) is expressed as ΔTSx/yW-V,
- the optical filter satisfies requirements ΔTS0/40380-530≤3%, ΔTS0/40450-650≤3%, and ΔTS0/40530-750≤3%,
- the normalized spectral transmittance being determined by normalization of a spectral transmittance for each of the incident angles so that the maximum of the spectral transmittance for each of the incident angles in the wavelength range of 400 to 650 nm is 100% and
- ΔTS0/v380-530 is 1.9% or less when y is in the range of 35 to 65.
Dependencies are inferred from the claim text.