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

Claim 1:
2. An optical filter provided on a substrate, the optical filter comprising in order from a substrate side:
a first layer made of a material whose extinction coefficient at the 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 number of films constituting the first layer is larger than a number of films constituting the second layer, 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.