| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical recording medium capable of recording and reproducing a signal with an optical pickup used for reproducing DVD, even if the density becomes higher than that of DVD or the like. SOLUTION: This optical recording medium 10 has a substrate 1, a recording layer 2, a thermally expanding layer 3, a space 4 and a light transmissive substrate 5. When the medium 10 is irradiated with a laser beam LB from the substrate 5 side, a region of the thermally expansive layer 3 having a raised temperature from irradiation by the laser beams LB expands towards the substrate 5. The expanded region 20 has a lens effect with respect to the laser beam LB and condenses the laser beam LB to a greater extent at the irradiation spot. Thus, the spot diameter in the case of the presence of the expanded region 20 is made smaller than the spot diameter in the case of the absence of the expanded region 20. |
