Optical filter and imaging apparatus

Patent metadata

Field	Value
Publication number	US-2025116802-A1
Application number	US-202418988429-A
Country	US
Kind code	A1
Filing date	Dec 19, 2024
Priority date	Jun 24, 2022
Publication date	Apr 10, 2025
Grant date	—

Abstract

An optical filter includes a glass substrate having a first main surface and a second main surface opposite each other and including phosphoric acid glass, a first antireflective layer disposed directly or indirectly on the first main surface of the glass substrate, and a resin layer, containing dye, disposed as one or more layers directly or indirectly on the second main surface of the glass substrate, wherein the glass substrate includes a predetermined range of amount of oxides, wherein the dye has a maximum absorption wavelength in the resin layer at a wavelength range of 690 to 800 nm, wherein thickness of the resin layer is 10 μm or less, wherein the optical filter has all spectral characteristics specified in (a- 1 ) to (a- 6 ), and wherein a Haze value of the optical filter is 2% or less.

First claim

What is claimed:

1 . An optical filter comprising:
a glass substrate having a first main surface and a second main surface opposite each other and including phosphoric acid glass; a first antireflective layer disposed directly or indirectly on the first main surface of the glass substrate; and a resin layer, containing dye, disposed as one or more layers directly or indirectly on the second main surface of the glass substrate, wherein the glass substrate includes, in a percentage by mass on an oxide basis: 50 to 80% of P 2 O 5 ; 5 to 20% of Al 2 O 3 ; 4 to 20% of CuO; 0.5 to 15% of R(1) 2 O, wherein R(1) is at least one component selected from a group consisting of Li, Na, K, Rb, and Cs; and 0 to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr, and Zn, wherein the dye has a maximum absorption wavelength in the resin layer at a wavelength range of 690 to 800 nm, wherein a thickness of the resin layer is 10 μm or less, wherein the optical filter has spectral characteristics specified as: (a-1) a transmittance T (t)450 at a wavelength of 450 nm is 80% or more at incidence angles of 0° and 500; (a-2) an average transmittance T (t)ave1 in a wavelength range of 450 to 600 nm is 78% or more at incidence angles of 0° and 50°; (a-3) a maximum transmittance T (t)max1 in the wavelength range of 450 to 600 nm is 85% or more at incidence angles of 0° and 50°; (a-4) a minimum wavelength λ (t)50 at which the transmittance is 50% is in a range of 600 to 650 nm at incidence angles of 0° and 50°; (a-5) an average transmittance T (t)ave2 in a wavelength range of 750 to 1200 nm is 4.0% or less at incidence angles of 0° and 50°; and (a-6) a maximum transmittance T (t)max2 in a wavelength range of 1000 to 1200 nm is 15% or less at incidence angles of 0° and 50°, and wherein a Haze value of the optical filter is 2% or less.

2 . The optical filter according to claim 1 , wherein when light is incident from a direction of the first main surface of the glass substrate, the optical filter has spectral characteristics specified as:
(a-7) a maximum reflectance R (t)max1 in a wavelength range of 450 to 700 nm is 7% or less at incidence angles of 5° and 50°; and (a-8) a maximum reflectance R (t)max2 in a wavelength range of 700 to 1200 nm is 45% or less at incidence angles of 5° and 50°.

3 . The optical filter according to claim 1 , wherein a second antireflective layer is disposed directly or indirectly on the second main surface of the glass substrate.

4 . The optical filter according to claim 3 , wherein:
the second main surface of the glass substrate is coated with the resin layer; the resin layer has a maximum absorption wavelength in a wavelength range of 650 to 850 nm; and the second antireflective layer is disposed directly or indirectly on the resin layer.

5 . The optical filter according to claim 3 , wherein when transmittance (%) is referred to as T and reflectance (%) is referred to as R, absorptivity is expressed by a following formula (1):

Absorptivity
⁢

(
%
)

=

100
-
T
-
R

,

(
1
)

wherein when light is incident from a direction of the first main surface of the glass substrate, the optical filter has spectral characteristics specified as:
(a-9) an average absorptivity of 15% or less at an incidence angle of 0° and a reflection angle of 5° in a wavelength range of 450 to 600 nm; and
(a-10) an average absorptivity of 88% or more at an incidence angle of 0° and a reflection angle of 5° in a wavelength range of 600 to 1200 nm.

6 . The optical filter according to claim 5 having spectral characteristics specified as:
(a-11) a difference between an average absorptivity at an incidence angle of 0° and a reflection angle of 5° and an average absorptivity at an incidence angle of 50° and a reflection angle of 50° in a wavelength range of 450 to 600 nm is 3% or less; and
(a-12) a difference between the average absorptivity at the incidence angle of 0° and the reflection angle of 5° and the average absorptivity at the incidence angle of 50° and the reflection angle of 50° in the wavelength range of 600 to 1200 nm is 5% or less.

7 . The optical filter according to claim 6 , wherein:
when the absorptivity calculated from the formula (1) is referred to as X, an absorbance is expressed by a following formula (2):

Absorbance
=

-
log

⁢
10
⁢

(

X
/
100

)

;

(
2
)

when the optical filter satisfies the following relational expression, where B1 is an absorbance at a wavelength of 450 nm, B2 is an absorbance at a wavelength of 500 nm, B3 is an absorbance at a wavelength of 550 nm, and B4 is an absorbance at a wavelength of 600 nm at an incidence angle of 0° and a reflection angle of 5°.

1
<

B
⁢
2
/
B
⁢
1

0
<

B
⁢
3
/
B
⁢
2

<
1

0
<

B
⁢
4
/
B
⁢
3

<
1

8 . The optical filter according to claim 1 , wherein when transmittance (%) at an incidence angle of 5° is referred to as T (5) and reflectance (%) at an incidence angle of 5° is referred to as R (5) , internal transmittance is expressed by a following fo

Assignees

• Agc Inc

Inventors

• Shiono Kazuhiko
• Shimada Takuro
• ORITA Yuichiro
• Sakagami Takahiro
• Nagata Takashi
• Kamijyo Katsushi

Classifications

• G02B5/226

  Glass filters · CPC title

• G02B5/223

  containing organic substances, e.g. dyes, inks or pigments · CPC title

• G02B5/208

  for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation · CPC title

• G02B1/11

  Anti-reflection coatings · CPC title

• G02B5/22 Primary

  Absorbing filters {(G02B5/201 - G02B5/208 take precedence)} · CPC title