Optical recording medium, holographic recording and/or retrieval method and holographic recording and/or retrieval apparatus

A holographic recording and/or retrieval method, which records a hologram in an optical recording medium and/or retrieves a recorded hologram, comprising the steps of:

• during recording, recording a hologram by simultaneously irradiating a recording layer of the optical recording medium with signal light of a predetermined wavelength and reference light;
• and
• during retrieval, guiding reading light of a wavelength that does not change a refractive index or absorption coefficient held in the recording layer through the recording layer, and retrieving a hologram by diffracted light produced when the reading light is guided through the recording layer,
• the optical recording medium comprising a substrate and the recording layer being formed on a surface of the substrate, through which light having an incident angle of a predetermined value or more with respect to the surface is guided, and which changes a refractive index or absorption coefficient upon simultaneous irradiation of the signal light of the predetermined wavelength and reference light, and can record a hologram by holding the changed refractive index or absorption coefficient.

A holographic recording and/or retrieval apparatus, which records a hologram in an optical recording medium and/or retrieves a recorded hologram, comprising:

• a signal light irradiating unit that irradiates a predetermined area of a recording layer of the optical recording medium with signal light of a predetermined wavelength from a direction crossing with a guide direction of the recording layer;
• a reference light irradiating unit that irradiates the predetermined area with reference light of a predetermined wavelength so as to change a refractive index or absorption coefficient of the recording layer by interference action with the signal light;
• and
• a reading light inputting unit that inputs reading light of a wavelength that does not change the refractive index or absorption coefficient held in the recording layer so as to guide it through the recording layer,
• the optical recording medium comprising a substrate and the recording layer being formed on a surface of the substrate, through which light having an incident angle of a predetermined value or more with respect to the surface is guided, and which changes the refractive index or absorption coefficient upon simultaneous irradiation of the signal light of the predetermined wavelength and reference light, and can record a hologram by holding the changed refractive index or absorption coefficient.