OPTICAL RECORDING AND READING METHOD

摘要

PURPOSE:To enable optical recording with small-sized lightweight semiconductor laser which radiates infrared rays having 800-850nm wavelength by incorporating a polydiacetylene deriv. compound and an AZ compound which absorbs infrared rays having 800-850nm wavelength into a recording layer. CONSTITUTION:A used optical recording medium has a recording layer contg. a polydiacetylene deriv. compound and an azulenium salt compound having a skeleton represented by formula I (where each of R1-R7 is H, halogen or a univalent org. residue). Infrared rays having 800-850nm wavelength are projected on the optical recording medium in accordance with the information to be recorded to discolor the projected parts of the recording layer and the recorded information is read by projecting visible light having 500-750nm wavelength on the recording layer. The azulenium salt compound (AZ compound) has an absorption peak in a wavelength range of >=750nm and generates heat under infrared light having >=750nm wavelength.