OPTICAL FILTER, AND DEVICE USING SAID FILTER

摘要

[Problem] To provide an optical filter with which improvements are made with respect to problems of conventional optical filters such as near infrared cut-off filters, which has a broad angular field of view and a high visible light transmittance, and which exhibits excellent ray cut-off properties even with respect to a relatively long wavelength range, namely wavelengths in the range 1100-1200 nm. [Solution] Provided is an optical filter provided with: a transparent resin substrate including a near-infrared absorption pigment; and a near-infrared reflective film formed upon at least one surface of the substrate. The optical filter satisfies conditions (A) to (D): (A) that the average transmittance of the filter measured from an orthogonal direction be at least 75% for wavelengths in the range 430-580 nm; (B) that the average reflectance of the filter measured from at least one surface thereof when measured from an angle of 5˚ with respect to the orthogonal direction be at least 80% for wavelengths in the range 800-1000 nm; (C) that the average reflectance of the filter measured from at least one surface thereof when measured from an angle of 5˚ with respect to the orthogonal direction be at least 70% for wavelengths in the range 1100-1200 nm; and (D) that the absolute value of the difference between the value (Xa) of the longest wavelength at which the transmittance of the filter measured from the orthogonal direction is 50% for wavelengths in the range 560-800 nm, and the value (Xb) of the longest wavelength at which the transmittance of the filter measured from an angle of 30˚ with respect to the orthogonal direction is 50% for wavelengths in the range 560-800 nm, be less than 15 nm.