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US 5,249,076 AGranted
Optical filter structure
AssigneesHoya Corporation, Dainippon Plastics Co., Ltd.
InventorsShigetoshi Fujiwara, Yoshio Kishima, Tadasu Inoue
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AssigneesHoya Corporation, Dainippon Plastics Co., Ltd.
InventorsShigetoshi Fujiwara, Yoshio Kishima, Tadasu Inoue
Estimating the term…
Provided is an optical filter structure which has excellent solarization resistance, and stably gives a constant wavelength distribution and constant irradiation energy for a long time, and which efficiently cuts off infrared light including near infrared light and ultraviolet light having a short wavelength and is sufficiently permeable to visible light. The optical filter structure has a glass filter 7 formed of phosphate or fluorophosphate glass containing 0.1 to 5% by weight, as an oxide, of copper oxide and an aquafilter 6 having a liquid layer 5 measuring 3 to 50 mm as a light path length, the glass filter 7 being placed either outside a container wall, 2a or 2b, of the aquafilter 6 or within the liquid layer 5, and the optical filter structure has optical characteristics that the absorption edge on a short wavelength side is a region of light having a wavelength of 250 to 330 nm and that the maximum value of the spectral transmittance on a long wavelength side beyond 780 nm is not more than 40%.
An optical filter structure (I) comprising a glass filter formed of phosphate or fluorophosphate glass containing 0.1 to 5% by weight, as an oxide, of copper oxide and an aquafilter having a liquid layer having a light path length of 3 to 50 mm, (II) said glass filter being positioned outside a wall of a container of said aquafilter or within said liquid layer, and (III) an absorption edge on a short wavelength side being in the range of from 250 to 330 nm, and the maximum of a spectral transmittance for light on a long wavelength side beyond 780 nm being not more than 40%.
A weathermeter which comprises an optical filter structure (I) comprising a glass filter formed of phosphate or fluorophosphate glass containing 0.1 to 5% by weight, as an oxide, of copper oxide and an aquafilter having a liquid layer having a light path length of 3 to 50 mm, (II) said glass filter being positioned outside a wall of a container of said aquafilter or within said liquid layer, and (III) an absorption edge on a short wavelength side being in the range of from 250 to 330 nm, and the maximum of a spectral transmittance for light on a long wavelength side beyond 780 nm being not more than 40%.
Dependencies are inferred from the claim text.