| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head device and an optical information recording/reproducing device capable of correctly detecting a radial tilt of an optical recording medium without generating an offset in a radial tilt signal even if an objective lens is shifted in the radial direction of the optical recording medium. SOLUTION: Exit light from a semiconductor laser is divided into three light of zero-order light being a main beam and ±1st-order diffracted light being a sub beam by a diffraction optical element, and three light condensing spots are shifted in the radial direction of a disk and are arranged. Three reflected light from the disk is diffracted as +1st-order diffracted light by a hologram optical element 8 and is received by a photodetector. The radial tilt of the disk for each of the main beam and the sub beam are detected based on the difference between the intensity of +1st-order diffracted light from areas 15, 18, 19, 22 of the hologram optical element 8 and the intensity of +1st- order diffracted light from areas 16, 17, 20, 21 of the same. |
