Basic layer for an optical filter
The present invention provides a basic layer for an optical filter, an optical filter, and their application for an image capture device. The present invention provides a basic layer for an optical filter and an optical filter having excellent optical properties while exhibiting excellent durability including a moisture-resistant layer.
1 . A basic layer for an optical filter, the basic layer comprising:
an infrared absorption substrate; and
a moisture-resistant layer disposed on one or both surfaces of the infrared absorption substrate,
wherein the moisture-resistant layer comprises at least one selected from the group consisting of polysilazane, polysilane, polycarbosilane, fluoro-resin, epoxy resin, urethane resin, polysilsesquioxane, polycarbonate and polysiloxane, each having an average unit of Chemical Formula 3:
wherein, in the Chemical Formula 3, R comprises an epoxy group, an amino group, a (meth)acrylic group, a (meth)acryloyloxy group, a (meth)acryloyloxyalkyl group, a mercapto group, a mercaptoalkyl group, a ureido group, an isocyanate group, a hydroxy group, or an isocyanatoalkyl group and a is 0.01 or more and less than 4;
wherein a ripple value at an incident angle of 0 degree of the basic layer in a wavelength range of 450 nm to 560 nm is 7% or less, and
wherein an absolute value of ΔT V according to Equation 1 is 30% or less:
△
T
V
=
100
×
(
T
V
.
f
-
T
V
.
i
)
/
T
V
.
i
,
and
[
Equation
1
]
wherein the T V.f is an average transmittance of the basic layer in a wavelength range of 425 nm to 560 nm after maintaining the basic layer at a temperature of about 85° C. and a relative humidity of 85% for 120 hours, and the T V.i is an average transmittance of the basic layer in the wavelength range of 425 nm to 560 nm before maintaining the basic layer at the temperature and the relative humidity.
2 . The basic layer of claim 1 , wherein an average transmittance of the basic layer in a wavelength range of 800 nm to 1000 nm is 6% or less.
3 . The basic layer of claim 1 , wherein a T50% cut-off wavelength of the basic layer is from 590 nm to 660 nm.
4 . The basic layer of claim 3 , wherein an average transmittance of the basic layer in a wavelength range of 425 nm to 560 nm of a transmission band is 75% or more.
5 . The basic layer of claim 1 , wherein the moisture-resistant layer is in contact with the infrared absorption substrate and wherein an adhesion strength of the moisture-resistant layer according to ASTM D3359 standard is 3B or more.
6 . The basic layer of claim 1 , wherein the infrared absorption substrate is a CuO containing fluorophosphate glass substrate or a CuO containing phosphate glass substrate.
7 . The basic layer of claim 1 , wherein the moisture-resistant layer has a thickness in a range of approximately 0.01 μm to 10 μm.
8 . The basic layer of claim 1 , further comprising a light absorption layer on one or both surfaces of the infrared absorption substrate.
9 . An optical filter comprising:
the basic layer of claim 1 ; and
a dielectric film formed on one or both surfaces of the infrared absorption substrate of the basic layer for an optical filter.
10 . The optical filter of claim 9 , wherein the dielectric film comprises a first sub-layer and a second sub-layer, wherein the first sub-layer and the second sub-layer have different refractive indices from each other, and wherein the first sub-layer and the second sub-layer are alternately stacked.
11 . The optical filter of claim 10 , wherein the first sub-layer and the second sub-layer are formed such that a V value according to the Equation 2 below is 17 or less:
V
=
K
×
{
[
(
n
1
/
n
2
)
2
p
×
(
n
1
2
/
n
s
)
-
1
]
/
[
(
n
1
/
n
2
)
2
p
×
(
n
1
2
/
n
s
)
+
1
]
}
2
[
Equation
2
]
wherein n 1 is a refractive index of the first sub-layer, n 2 is a refractive index of the second sub-layer, n s is a refractive index of the infrared absorption substrate, K is a total number of the first sub-layer and the second sub-layer in the dielectric film, and p is a number satisfying K=(2p+1).
12 . The optical filter of claim 11 , wherein a ratio (n 1 /n 2 ) of the refractive index (n 1 ) of the first sub-layer relative to the refractive index (n 2 ) of the second sub-layer is in a range of 1.4 to 2.0.
13 . The optical filter of claim 12 , wherein the refractive index n 1 of the first sub-layer is in a range of 1.8 to 3.5.
14 . The optical filter of claim 11 , wherein a ratio (n 1 /n s ) of the refractive index (n 1 ) of the first sub-layer relative to the refractive index (n s ) of the infrared absorption substrate is in a range of 1.4 to 2.0.
15 . The optical filter of claim 11 , wherein K in Equation 2 is 15 or less.
16 . The optical filter of claim 11 , wherein a thickness of each of the first sub-layer and the second sub-layer is from 5 nm to 200 nm and wherein an average value of the thickness of the first sub-layer and the thickness of the second sub-layer in the dielectric film is from 5 nm to 70 nm.
17 . The optical filter of claim 9 , wherein the dielectric film has a thickness in a range of 100 nm to 500 nm.
18 . The optical filter of claim 9 , wherein the dielectric film is formed on both surfaces of the infrared absorption substrate.
19 . An image capturing device comprising the optical filter of claim 10 .