Optical filter, and solid-state image pickup device and camera module using the optical filter
The problem of the present invention is to overcome drawbacks of conventional optical filters such as near-infrared cut filters and to provide an optical filter which generates little scatted light even during light absorption and has excellent transmittance property. The optical filter of the present invention is characterized by containing a squarylium-based compound and a compound which absorbs or quenches fluorescence of the squarylium-based compound. The optical filter of the present invention preferably contains a near-infrared absorbing dye containing a squarylium compound (A) and at least one compound (B) selected from the group consisting of a phthalocyanine-based compound (B-1) and a cyanine-based compound (B-2).
1. An optical filter comprising:
A near-infrared absorbing dye which comprises a squarylium-based compound (A), and a compound which absorbs fluorescence of the squarylium-based compound (A),
wherein the absorption maximum of the squarylium-based compound (A) is present on the side of shorter wavelength than the absorption maximum of the compound,
wherein the squarylium-based compound (A) has the absorption maximum in the wavelength region of not less than 650 nm but less than 740 nm, and the compound has the absorption maximum in the wavelength region of more than 670 nm but not more than 760 nm, and the difference in the absorption maximum wavelength between the squarylium-based compound (A) and the compound is from 1 to 100 nm, and
wherein an average transmittance of the optical filter in a wavelength region of from 430 nm to 580 nm is at least 87%, and an average transmittance of the near-infrared cut filter in a wavelength region of from 800 nm to 1000 nm is at most 1%.
2. The optical filter according to claim 1 , further comprising at least one near-ultraviolet absorbing agent selected from the group consisting of an azomethine-based compound, an indole-based compound, a benzotriazole-based compound and a triazine-based compound.
3. The optical filter according to claim 1 , which is for a solid-state image pickup device.
4. A solid-state image pickup device equipped with the optical filter according to claim 1 .
5. A camera module equipped with the optical filter according to claim 1 .
6. The optical filter according to claim 1 , comprising a resin substrate which comprises a resin, the squarylium-based compound (A), and the compound.
7. The optical filter according to claim 6 , wherein the resin is at least one resin selected from the group consisting of a cyclic polyolefin-based resin, an aromatic polyether-based resin, a polyimide-based resin, a fluorene polycarbonate-based resin, a fluorene polyester-based resin, a polycarbonate-based resin, a polyamide-based resin, a polyarylate-based resin, a polysulfone-based resin, a polyether sulfone-based resin, a polyparaphenylene-based resin, a polyamidoimide-based resin, a polyethylene naphthalate-based resin, a fluorinated aromatic polymer-based resin, a (modified) acrylic resin, an epoxy-based resin, an allyl ester-based curing resin and a silsesquioxane-based ultraviolet curing resin.
8. The optical filter according to claim 1 , wherein the resin substrate is formed on an optical part made of a glass plate, quartz, or transparent plastic.
9. The optical filter according to claim 1 , wherein the difference in the absorption maximum wavelength between the squarylium-based compound (A) and the compound which absorbs fluorescence of the squarylium-based compound (A) is from 5 to 80 nm.
10. The optical filter according to claim 1 , wherein the difference in the absorption maximum wavelength between the squarylium-based compound (A) and the compound which absorbs fluorescence of the squarylium-based compound (A) is from 10 to 60 nm.