Optical information recording medium and information recording and reproducing method thereof

摘要

An optical information recording medium, wherein concave and convex shaped guide grooves narrower in width W than the spot diameter of the laser beam is formed in the face of the recording film layer of a substrate, and the recording film layer undergoes optically detectable changes caused by the application of a laser beam thereto, the detectable changes being due to the changes in the optical phase of the reflected light or the transmitted light, and the changes in the optical phase being caused in the direction of reducing the optical phase difference between concave and convex portions of guide grooves disposed in the substrate.