| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical element for solving the problem that there is no optical diffraction element for satisfying both light transmission efficiency for a DVD and a birefringence influence of a CD, and an optical pickup using the same. <P>SOLUTION: Optical beams of a wavelength λ<SB>1</SB>emitted from a laser light source 1 are reflected by an optical element 11 through a collimator lens 4 and transmit through a polarizing element 7 obtained by forming integrally a polarizing hologram 5 and a wavelength board 6 that generates 5λ<SB>1</SB>×(1/4) phase difference to light of the wavelength λ<SB>1</SB>. In addition, optical beams of a wavelength λ<SB>2</SB>pass through the collimator lens 4 and then, are partially diffracted as ±primary light in the optical element 11 while most of the remaining optical beams are reflected as zero-order light. The light reflected as zero-order light in the optical element 11 of a wavelength λ<SB>2</SB>transmit through the polarizing element 7, but are not diffracted by the polarizing hologram 5. The light of wavelengths λ<SB>1</SB>and λ<SB>2</SB>transmitting through the polarizing element 7 form spots on optical disks 9 and 10 with different substrate thickness, respectively by an objective lens 8. <P>COPYRIGHT: (C)2007,JPO&INPIT |
