IR cut filter
An IR cut filter includes an infrared light absorber to absorb infrared light, and an infrared light reflector to reflect infrared light. The infrared light absorber has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 620 to 670 nm. The infrared light reflector has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 670 to 690 nm. The wavelength with respect to which the infrared light reflector has the 50% transmittance is longer than the wavelength with respect to which the infrared light absorber has the 50% transmittance. A combination of the infrared light absorber and the infrared light reflector provides a light transmission property of 50% transmittance with respect to a wavelength in the 620 to 670 nm wavelength band and less than 5% transmittance with respect to a 700 nm wavelength.
1. An infrared (IR) cut filter to block infrared light, the IR cut filter comprising:
an infrared light absorber configured to absorb the infrared light; and
an infrared light reflector configured to reflect the infrared light,
wherein the infrared light absorber has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 620 nm to 670 nm and 10% to light 40% transmittance with respect to a wavelength of 700 nm,
wherein the infrared light reflector has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 670 nm to 690 nm,
wherein the wavelength with respect to which the infrared light reflector has the 50% transmittance is longer than the wavelength with respect to which the infrared light absorber has the 50% transmittance, and
wherein a combination of the infrared light absorber and the infrared light reflector provides a light transmission property of 50% transmittance with respect to a wavelength in the wavelength band of 620 nm to 670 nm, 20% to 40% transmittance with respect to a wavelength of 675 nm, and less than 5% transmittance with respect to a wavelength of 700 nm.
2. The IR cut filter according to claim 1 ,
wherein the infrared light reflector has a light transmission property of less than 15% transmittance with respect to a wavelength of 700 nm.
3. The IR cut filter according to claim 1 , wherein the infrared light reflector has light transmission properties of equal to or more than 80% transmittance with respect to each wavelength in a wavelength band of 450 nm to 650 nm, and equal to or more than 90% average transmittance in the wavelength band of 450 nm to 650 nm.
4. The IR cut filter according to claim 1 , wherein a single infrared light reflector is disposed on one principal surface of a single infrared light absorber.
5. An imaging unit, comprising the IR cut filter according to claim 1 .
6. An infrared (IR) cut filter to block infrared light, the IR cut filter comprising:
an infrared light absorber configured to absorb the infrared light; and
an infrared light reflector configured to reflect the infrared light,
wherein the infrared light absorber has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 640 nm to 670 nm and 10% to 40% transmittance with respect to a wavelength of 700 nm,
wherein the infrared light reflector has a light transmission property of 50% transmittance with respect to a wavelength in a wavelength band of 670 nm to 690 nm,
wherein the wavelength with respect to which the infrared light reflector has the 50% transmittance is longer than the wavelength with respect to which the infrared light absorber has the 50% transmittance, and
wherein a combination of the infrared light absorber and the infrared light reflector provides a light transmission property of 50% transmittance with respect to a wavelength in the wavelength band of 640 nm to 670 nm and less than 5% transmittance with respect to a wavelength of 700 nm.
7. The IR cut filter according to claim 6 ,
wherein the infrared light reflector has a light transmission property of less than 15′% transmittance with respect to a wavelength of 700 nm.
8. The IR cut filter according to claim 6 , wherein the infrared light reflector has light transmission properties of equal to or more than 80% transmittance with respect to each wavelength in a wavelength band of 450 nm to 650 nm, and equal to or more than 90% average transmittance in the wavelength band of 450 nm to 650 nm.
9. The IR cut filter according to claim 6 , wherein a single infrared light reflector is disposed on one principal surface of a single infrared light absorber.
10. An imaging unit comprising the IR cut filter according to claim 6 .