INFORMATION RECORDING MEDIUM

摘要

PURPOSE:To obtain an information recording medium which does not require an automatic focusing system by forming a recording medium of a metal or alloy which has at least two kinds of crystal structure in a solid state, maintains the crystal structure of one temp. region in the other temp. region and/or induces the volumetric changes different from each other in a crystal state. CONSTITUTION:An objective lens which condenses the light from a light source and forms a spot is united to the recording medium. The recording medium is formed of the metal or alloy which has at least two kinds of the crystal structure in the solid state, maintains the crystal structure of one temp. region in the other temp. region and/or induces the volumeric changes different from each other in the crystal state. The optical disk which does not require automatic focusing is thus constituted. The high density and high speed recording and reproducing are possible even if the rotating speed of the disk is decreased by scanning the disk with a beam in the radial direction thereof by using a galvanomirror.