Optical disk, an optical disk barcode forming method, an optical disk reproduction apparatus, a marking forming apparatus, a method of forming a laser marking on an optical disk, and a method of manufacturing an optical disk

A reproducing apparatus for reproducing information on such an optical disk comprising:

• a first recording area where main information is recorded,
• a second recording area where barcode-like marks, each of which has a strip-like configuration in a radius direction and which are disposed in a circumferential direction, are recorded as sub information on said first recording area, wherein
• said first recording area contains at least a lead-in area from which data recording starts, and a control data area which represents a physical property of the optical disk,
• said second recording area is disposed inside said control data area on said first recording area, and
• said sub information is disposed at a radial position which lies closer to the disk center than the radial position of the control data area, and
• a reproduced frequency of said main information is higher than a reproduced frequency of said sub information;
• wherein
• said apparatus reproduces recorded contents of said main information on the first recording area and said sub information on the second recording area by using a common optical pick up while rotating the optical disk, and
• when said apparatus reproduces from the second recording area by using the optical pick up, the apparatus extracts the sub information on the second recording area by suppressing the main information on the first recording area among the read out signals by suppressing high frequency signals having a frequency higher than the sub information.