Patent ID: 6226257
Filing Date: 2001-05-01
Classification: G11B

Abstract:
An optical information storage medium having a plurality of grooves and a plurality of lands alternately formed, each of said grooves and each of said lands functioning as recording tracks to form an information storage region, said optical information storage medium comprising:a first header region having a plurality of first phase pits respectively formed along imaginary lines extended from said plurality of lands; anda second header region having a plurality of second phase pits respectively formed along imaginary lines extended from said plurality of grooves;wherein each of said grooves has an optical depth of approximately 3.lambda./8 where .lambda. is the wavelength of a light beams to be used;each of said first phase pits has an effective optical depth of approximately .lambda./8;each of said second phase pits has an optical depth substantially equal to that of each of said grooves; andsaid first header region and said second header region are shifted from each other along the imaginary extension lines of each of said grooves.