| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for use in an optical pickup, which is small and has a long working distance and also has high optical performances over the whole range of wavelengths 390nm to 420nm. <P>SOLUTION: This objective lens is an objective lens 1 to be used in a blue laser pickup and it is constituted of a compound lens in which a glass lens 1a by optical glass material whose numerical aperture of the side of an optical information recording medium is 0.85 or more and whose outer diameter D<SB>1</SB>is below 5.0mmϕ and a resin lens 1b by resin material are integrated and it has a long working distance such as that the ratio L/E of a working distance L and the flux diameter E of an incident light beam becomes 1/6 or more and the wave front aberration of the compound lens is below 0.04λ in the whole range of wavelengths 390nm to 420nm. <P>COPYRIGHT: (C)2004,JPO |
