| 摘要 |
According to a method for designing an optical pickup including a monolithic laser diode that emits a laser light beam for DVD recording and a laser light beam for CD playback, two photodetective portions provided on the same substrate for receiving the laser light beams, and an objective lens, for each of the emitting portions of the monolithic laser diode for emitting the DVD recording and CD playback laser light beams respectively, the specification of the error of the emission direction thereof is determined according to the following formula: |(Deltatheta ⊥<SUB>1</SUB>xDeltatheta<SUB>1</SUB>xDpd<SUB>1</SUB>/Dob<SUB>1</SUB>-Deltatheta ⊥<SUB>2</SUB>xDeltatheta<SUB>2</SUB>xDpd<SUB>2</SUB>/Dob<SUB>2</SUB>)xKpd<SUB>2</SUB>|<=7, where, let the variables corresponding to the DVD recording laser light beam be followed by a subscript "1" and variables corresponding to the CD playback laser light beam be followed by a subscript "2", Deltatheta ⊥ represents the emission angle; Deltatheta represents the sensitivity, to the emission angle, of the deviation of the gravity center of the intensity of the light exiting from the object lens; Dob represents the diameter of the light beam immediately after exiting from the object lens; Dpd represents the diameter of the spot formed by the light beam on the photodetective portion; Kpd represents the sensitivity of the deviation of light reception balance to the deviation of the photodetective portion; and a represents the tolerable value for the remnant deviation of light reception balance.
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