Aberration compensating device and optical head device

1. An aberration compensating device for compensating aberration of a laser beam which is emitted from a light source and converged on an optical recording disk through an objective lens comprising:

a liquid crystal panel including a liquid crystal layer whose refractive index is changed in accordance with an applied voltage and transparent electrodes which are disposed so as to interpose the liquid crystal layer therebetween; and

a liquid crystal panel control part for controlling the applied voltage which is applied to the transparent electrodes;

wherein at least one of the transparent electrodes includes a center part in an approximately circular shape and an outer peripheral part surrounding the center part, and the outer peripheral part includes a plurality of outer peripheral divided parts which are divided around the center part, and

when a diameter of an incident area of the laser beam corresponding to a pupil diameter of the objective lens on the liquid crystal panel is set to be “D1” and a diameter of the center part is set to be “D2”, (D2/D1) is set at a value in the range 0.5 to 0.65.

2. The aberration compensating device according to claim 1 , wherein the (D2/D1) is set at a value in the range 0.52 to 0.6.

3. The aberration compensating device according to claim 1 , wherein the voltage is independently set which is respectively applied to the center part and the outer peripheral divided parts.

4. The aberration compensating device according to claim 1 , wherein the outer peripheral divided parts comprise eight sections divided by an approximately equal angle around the center part.

5. The aberration compensating device according to claim 1 , wherein each of the transparent electrodes includes the center part and the outer peripheral part.

6. An optical head device comprising:

a light source;

an objective lens for converging a laser beam emitted from the light source on an optical recording disk; and

an aberration compensating device which is disposed between the light source and the objective lens for compensating aberration of the laser beam;

wherein the aberration compensating device comprises;

a liquid crystal panel including a liquid crystal layer whose refractive index is changed in accordance with an applied voltage and transparent electrodes which are disposed so as to interpose the liquid crystal layer therebetween; and

a liquid crystal panel control part for controlling the voltage which is applied to the transparent electrodes;

wherein at least one of the transparent electrodes includes a center part in an approximately circular shape and an outer peripheral part surrounding the center part, and the outer peripheral part includes a plurality of outer peripheral divided parts which are divided around the center part, and

when a diameter of an incident area of the laser beam corresponding to a pupil diameter of the objective lens on the liquid crystal panel is set to be “D1” and a diameter of the center part is set to be “D2”, (D2/D1) is set at a value in the range 0.5 to 0.65.

7. The optical head device according to claim 6 , wherein the (D2/D1) is set at a value in the range 0.52 to 0.6.

8. The optical head device according to claim 6 , wherein the voltage is independently set which is respectively applied to the center part and the outer peripheral divided parts.

9. The optical head device according to claim 6 , wherein the outer peripheral divided parts comprise eight sections divided by an approximately equal angle around the center part.

10. The optical head device according to claim 6 , wherein each of the transparent electrodes includes the center part and the outer peripheral part.