Patent ID: 11960110
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. An optical element comprising:
a substrate made of glass or plastic; and
an optical filter provided on the substrate,
wherein the optical filter comprises in order from a substrate side:
a first layer made of a material whose extinction coefficient at a wavelength of 550 nm is 0.02 or less;
an absorption layer having light absorbency; and
a second layer made of a material whose extinction coefficient at the wavelength of 550 nm is 0.02 or less, the substrate, the first layer, the absorption layer, and the second layer being mutually adjacent,
wherein a thickness of the substrate is 0.2 mm or more and 8.0 mm or less, and
wherein the following condition is satisfied:

R2−R1≥10[%]

where R1 [%] represents a reflectance of the optical filter for light whose wavelength is 550 nm and that makes incident on the optical filter from a side opposite to the substrate, and R2 [%] represents a reflectance of the optical filter for light whose wavelength is 550 nm and that makes incident on the optical filter from the substrate side.