Abstract: According to the method, the focusing servo is activated at the zero-crossing point of a focusing error signal FE immediately after the focusing error signal FE has exceeded the first threshold th1 or has dropped below the second threshold th2. The absolute value of the first threshold th1 and the second threshold th2 is reduced each time a predetermined time t is elapsed until the focusing servo is activated.

Abstract: The present invention provides an optical recording medium and an optical disk device realizing prevention of crosswrite and uniformity of playback signals and capable of easily securing compatibility with a read only disk. It provides an optical recording medium on which light LB condensed by a lens (12, 14) having a numerical aperture of 0.85±0.

Abstract: The present invention discloses a method for adjusting a tilt angle of an optical disc driver. The method includes the following steps. First, to move the optical pick up to close the outer end of the first and second guiding shafts. Next, the turntable drives a disc to rotate. Then, the light source provides a light to penetrate through the disc and the lens. The image sensor receives the reflection light from the disc and the lens. The monitor displays the traces projected from the reflection lights. According to the traces, the driving device adjusts the positions of the first and second guiding shafts.