Abstract: An information signal area on an information signal recording surface is provided as pits on a mirror in accordance with modulated information data, and is covered with a metal alloy reflective film. Sections that do not include pits corresponding to the information data are provided in the information signal area, and portions of the metal alloy reflective film on the sections are formed as perforated marks corresponding to the information data. In this case, the reproduction signal amplification level of a prepit signal and the reproduction signal amplitude level of a perforated mark signal can be obtained as substantially equal values by adjusting the depth and width of pits and/or adjusting the width and length of perforated marks. Hence, waveform distortion due to a waveform equalization circuit and variations in binary signals due to displacement of the slice level are reduced so that signals can be stably and reliably detected with the same reading apparatus.

Abstract: A read-only optical disc medium is disclosed. The disc medium includes: an information recording area in which information is recorded by means of an embossed pit array formed in a convexo-concave shape having a reflective layer deposited thereon; a test writing area which is used for test write recording of a mark formed by dissipating or decreasing the reflective layer; and an additional write area in which a record data string is formed of a mark by dissipating or decreasing the reflective layer under a recording condition decided in accordance with a result of test write recording performed in the test writing area.

Abstract: An optical disk read only memory having an information recording surface with a concave-convex pattern formed on the basis of a first signal and a reflective film covering the surface. The disc medium includes: an additional information recording section formed on a recording track of a first data string; and a second data string including a mark of removing or reducing the reflective film. The modulation methods of the first and the second data strings are identical, and Lh(n)>Lp1(n) and Wh(n)>(Wp1(n)+Wp2(n))/2 are satisfied, where a reference clock cycle is T, a data length is nT, a length and a width of the mark are Lh(n) and Wh(n), a length and a width of a base of the pit are Lp1(n), and Wp1(n), a length and a width of a top face of the pit is Lp2(n) exceeding Lp1(n), and Wp2(n) exceeding Wp1(n).

Abstract: An information signal area on an information signal recording surface is provided as pits on a mirror in accordance with modulated information data, and is covered with a metal alloy reflective film. Sections that do not include pits corresponding to the information data are provided in the information signal area, and portions of the metal alloy reflective film on the sections are formed as perforated marks corresponding to the information data. In this case, the reproduction signal amplification level of a prepit signal and the reproduction signal amplitude level of a perforated mark signal can be obtained as substantially equal values by adjusting the depth and width of pits and/or adjusting the width and length of perforated marks. Hence, waveform distortion due to a waveform equalization circuit and variations in binary signals due to displacement of the slice level are reduced so that signals can be stably and reliably detected with the same reading apparatus.

Abstract: An optical disk read only memory having an information recording surface with a concave-convex pattern formed on the basis of a first signal and a reflective film covering the surface. The disc medium includes: an additional information recording section formed on a recording track of a first data string; and a second data string including a mark of removing or reducing the reflective film. The modulation methods of the first and the second data strings are identical, and Lh(n)>Lp1(n) and Wh(n)>(Wp1(n)+Wp2(n))/2 are satisfied, where a reference clock cycle is T, a data length is nT, a length and a width of the mark are Lh(n) and Wh(n), a length and a width of a base of the pit are Lp1(n), and Wp1(n), a length and a width of a top face of the pit is Lp2(n) exceeding Lp1(n), and Wp2(n) exceeding Wp1(n).

Abstract: A read-only optical disc medium is disclosed. The disc medium includes: an information recording area in which information is recorded by means of an embossed pit array formed in a convexo-concave shape having a reflective layer deposited thereon; a test writing area which is used for test write recording of a mark formed by dissipating or decreasing the reflective layer; and an additional write area in which a record data string is formed of a mark by dissipating or decreasing the reflective layer under a recording condition decided in accordance with a result of test write recording performed in the test writing area.

Abstract: An optical disk checkup/measuring apparatus capable of shortening measuring time and of being incorporated into a manufacturing line and has a simple structure includes rotation driving elements (2,3) for driving rotation of an optical disk to be measured (10), a light emitting portion LD for emitting a light beam LF onto the optical disk to be measured (10), an optically detecting portion (D1, D2) for receiving and detecting the light beam LR reflected from the optical disk to be measured (10) and an operation processing portion (4, 5) for processing a signal received and detected by the optically detecting portion (D1, D2) so as to form a specified signal. The light emitting portion is composed of a plurality of light emitting elements LD provided in a radial direction of the optical disk to be measured (10), and the light beams are emitted successively from the light emitting elements LD onto the optical disk to be measured (10).

Abstract: A recording and/or reproducing apparatus for a magneto-optical recording medium includes a semiconductor laser device for radiating a laser beam to the magneto-optical recording medium, a driving circuit for supplying a driving signal to the semiconductor laser device, a first oscillating circuit for generating first high-frequency signals superposed on the driving signal from the driving circuit during recording on the magneto-optical recording medium, and a second oscillating circuit for generating second high-frequency signals superposed on the driving signal from the driving circuit during reproduction from the magneto-optical recording medium. The first high-frequency signals are of a frequency twice the maximum recording frequency or higher, and the second high-frequency signals are of a frequency different from that of the first high-frequency signals.