| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can write and/or reproduce information on various kinds of optical information recording mediums compatibly. <P>SOLUTION: This pickup maintains the tracking characteristics excellent by inputting the light flux of a wavelength λ1 to the objective lens OBJ in a state of limited convergent light by limiting the emission angle of the light flux of a wavelength λ3. On the other hand, the tracking characteristics are maintained excellent by designing the refraction surface of the objective lens OBJ to the light flux of a wavelength λ1 to reduce the amount of the sine condition violation ΔL, since the tracking characteristics may be degraded if the light flux of wavelength λ1 is input to the objective lens OBJ in the state of a limited convergent light. In this case, although the amount of sine condition violations becomes rather large for the light flux of the wavelength λ3, the tracking characteristics can be maintained at a certain level by suppressing the emission angle of the light flux of the wavelength λ3 as mentioned above. <P>COPYRIGHT: (C)2007,JPO&INPIT |
