Hoya Corporation

Dainippon Plastics Co., Ltd.

Shigetoshi Fujiwara

Yoshio Kishima

Tadasu Inoue

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%.

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Hachioji, Japan

Shigetoshi Fujiwara