Read signal evaluation method, information recording and reading method, and information recording and reading apparatus

An information recording method for recoding digital information in a recording medium so that the digital information is optically readable as an optical phase, comprising the steps of:

• optically reading the digital information stored in the recording medium, the digital information representing a phase signal, and the phase signal defined as a signal representing an optical phase difference between a phase of a reference light and a phase of a reading light;
• extracting, from the digital information, a predetermined digital pattern corresponding to a phase value;
• and
• changing a recording condition, so as to approximately equalize the extracted phase value to a predetermined value.

An information recording method for recoding digital information in a recording medium so that the digital information is optically readable as an optical phase, comprising the steps of:

• optically reading the digital information stored in the recording medium, the digital information representing a phase signal, the phase signal defined as a signal representing an optical phase difference between a phase of a reference light and a phase of a reading light;
• extracting, from the phase signal, a phase value corresponding to a predetermined digital pattern, and a shift, in a time axis direction, from a target wave corresponding to the predetermined digital pattern;
• and
• changing a recording condition, so as to approximately equalize the extracted shift in the time axis direction to a predetermined value.

A read signal evaluation apparatus comprising:

• a reading unit configured to read digital information stored in a recording medium, the digital information representing a phase signal, the phase signal defined as a signal representing an optical phase difference between a phase of a reference light and a phase of a reading light;
• a decoder configured to decode the phase signal;
• a pattern detector configured to detect a predetermined digital pattern in the result of the decoding by the decoder;
• and
• a calculator configured to calculate a statistical average of the phase signal from which the predetermined digital pattern is detected by the pattern detector.

A read signal evaluation apparatus comprising:

• a reading unit configured to read digital information stored in a recording medium as a phase signal;
• a decoder configured to decode the phase signal;
• a pattern detector configured to detect a predetermined digital pattern in the decoding result by the decoder;
• and
• a calculating means for calculating a statistical average of the phase signal from which the predetermined digital pattern is detected by the pattern detector;
• wherein the reading unit comprises a homodyne detection system.