Information recording medium and its production

Abstract

Abstract PURPOSE:To increase the recording density per unit track by forming plural series of pit arrays which are different in depth on the tracks of an optical disk. CONSTITUTION:Plural series of the pit arrays which are different in depth are formed to a photoresist by using plural beams of laser light having different exposing intensity, by which respectively different sets of information are provided in said plural series of the pit arrays. More specifically, the part of the 1st series pit 1 has depth D1 and the 2nd series pit 2 has depth D2; the 2nd series pit 2 positions in the middle of the 1st series pit 1 and eventually both the pits are formed as the independent and divided pits. The 1st series pit 1 and the 2nd series pit 2 are positioned respectively on one side and the other side relative to the center line A-A of the track. The pitch from which reflected light is discriminated by selecting the intensity level of the reflected light if the depths D1, D2 are respectively set at lambda/8, lambda/4, respectively when the wavelength of the reading out laser light is designated as lambda.

Inventors

• 👤 Masumi Fujita
• 👤 藤田　真純

Bibliographic Details