| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for BD which has high transmittance of the entire lens surface while securing a light spot diameter and sufficiently secures jitter and signal amplitude by securing the transmittance of both a lens center part and lens out circumference part. <P>SOLUTION: The tangent angle of 60 degrees or more exists on a laser incident side lens surface of an objective lens for BD, the laser incident side lens surface is provided with an anti-reflection film, and the anti-reflection film shows a first minimum value of light reflectance ratio in wavelength within the range of the wavelength 400 to 420 nm and shows a second minimum value of light reflectance ratio within the range of wavelength 556 to 712 nm of a long-wavelength side compared with the wavelength 420 nm when light is made incident perpendicularly on the center part of the laser incident side lens surface. <P>COPYRIGHT: (C)2013,JPO&INPIT |
