| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head, a light emitting and receiving element, and an optical recording medium recording and reproducing device that can conduct focus control of an objective lens with high accuracy in response to a tendency of a high recording density of an optical disk. SOLUTION: The optical head 2 is provided with a semiconductor laser 61, an optical diffractive element 65, an objective lens 70 and a photo detection element 74 or the like. Focal positions in the optical axis direction of two sub spots formed on the photo detection element 74 by the action of the diffractive element 65 differ from each other in the radial direction and moving the objective lens 70 in the optical axis direction allows the intensity distribution of the spots on the photo detection element 74 to indicate asymmetrical behaviors. Focus control of the objective lens 70 is corrected on the basis of the amplitude of a push-pull signal of the two sub spots detected by the photo detection element 74.
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