Patent ID: 7161744

Claim:
An objective lens for converging a monochromatic light flux having a specific wavelength in a range of 350 to 450 nm on an optical information recording medium while the objective lens is placed facing the optical information recording medium, the objective lens comprising: a lens body containing a polymer resin having an alicyclic structure; a first film having a refractive index of less than 1.7 for light having a wavelength of 405 nm; a second film having a refractive index of 1.7 or more for the light having the wavelength of 405 nm; and a third film having a refractive index of 1.55 or less for the light having the wavelength of 405 nm, wherein: the first film, the second film and the third film are provided on the lens body; the first film is provided between the lens body and the second film; the second film is provided between the first film and the third film; and a thickness of the first film is in a range of 50 to 15000 nm.