| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffraction element for diffracting two light beams having different wavelength to a prescribed angle, respectively, and to provide an optical pickup apparatus equipped with the diffraction element. <P>SOLUTION: The 1st light having the wavelength λ1 and the 2nd light having the wavelength λ2 are diffracted by the diffraction element. The diffraction element is provided with a substrate 1 on which a 1st pattern for diffracting the 1st light is formed, and a substrate 2 on which a 2nd pattern is formed. The substrates 1 and 2 are provided with an area D1 where the recessed part of the 1st pattern and the projecting part of the 2nd pattern overlap each other, an area D2 where the projecting part of the 1st pattern and the recessed part of the 2nd pattern overlap each other, an area D3 where the projecting parts of the 1st and 2nd patterns overlap each other and an area D4 where the recessed parts of the 1st and 2nd patterns overlap each other, and the shape of the 2nd pattern is adjusted so that a phase difference of the light having the wavelength λ2 may not exist between the area D1 and the area D2, and also, between the area D3 and the area D4, and the phase difference of the light having the wavelength λ2 may exist between the area D1 or the area D2 and the area D3 or the area D4. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
