| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a liquid crystal optical element which is utilized by being switched as a diffraction element and a non-diffraction element as light beams having a plurality of wavelengths are used and to provide an optical pickup apparatus using the liquid crystal optical element. <P>SOLUTION: As for concentric belt-like patterns disposed on a transparent substrate, belt-like pattern electrode widths determined by (2×m×f×λ)<SP>1/2</SP>(m:the number of pieces from a center of the plurality of belt-like patterns, f:focal distance, λ:wavelengths of used light beams) and gap widths between belt-like patterns positioned on the outer side of the belt-like patterns are set so that phase amount difference substantially becomes λ/2 in all regions where the light beams are phase modulated. <P>COPYRIGHT: (C)2010,JPO&INPIT |
