Patent ID: 6819498
Filing Date: 2004-11-16
Classification: G02B

Abstract:
A two-wavelength antireflection film for antireflection in two-wavelength regions of light between 200 nanometers and 850 nanometers wherein one of the two-wavelength regions ranges from about 200 nanometers to 350 nanometers and includes a design main wavelength and the other two-wavelength region extends from about 650 nanometers to 850 nanometers comprising:a substrate which is transparent in wavelength regions in which the substrate is to be used; a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4&lgr; to 0.1&lgr; for the design main wavelength (&lgr;); a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05&lgr; to 0.6&lgr; for the design main wavelength &lgr;; a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1&lgr; to 0.5&lgr; for the design main wavelength &lgr;; and a fourth thin film which is formed on the third thin film, and has a refractive index of 1.35 to 1.55 and optical film thickness of 0.2&lgr; to 0.35&lgr; for design main wavelength &lgr;.