| 摘要 |
PROBLEM TO BE SOLVED: To provide one optical detection system immune to disturbance by controlling a distance between a semispherical lens and an optical recording medium so as to fix the intensity of reflected light from a spot, where the recording layer of the optical recording medium is a crystal phase, by monitoring the reflected light intensity of light made incident from the semispherical lens to the optical recording medium. SOLUTION: A surface write type optical recording medium 1 constituted by using a phase change material and a semispherical lens 2 are constituted proximately. Light from a light source is converged to the optical recording medium 1 by an objective lens 3 and the semispherical lens 2, and information is recorded and/or reproduced and/or erased. The semispherical lens 2 is a semispherical fine convex lens arranging its plane part facing the optical recording medium 1 parallel with the recording plane of the optical recording medium 1. With the respective layers of the semispherical lens 2 and the optical recording medium 1 constituted, intensity of reflected light returned to the side of the semispherical lens is changed corresponding to a change in the distance between the semispherical lens 2 and the optical recording medium 1. |
