REPRODUCING METHOD FOR OPTICAL RECORDING MEDIUM

• Main Authors: KUME MINORU, TSUJIOKA TSUYOSHI, MATSUURA KOTARO, YAMAMOTO SHIGEAKI, TATEZONO FUMIO
• Format: Patent
• Language: English
• Published: 29.05.1990
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

PURPOSE:To provide the reproducing method which does not generate a reverse reaction by irradiating the optical recording medium on which information is recorded as a change in the state of a recording layer consisting of a photochromic material with light of the wavelength of a low absorptivity and detecting the change in the refractive index thereof. CONSTITUTION:A metallic reflecting film 2 is formed on a substrate 1 and a spiropyrane compd. which is the photochromic material is mixed with a resin and the mixture is applied thereon to form the recording layer 3. The spiropyrane compd. changes its light absorptivity before and after the irradiation with UV rays. Incident light LB1 is made into the reflected light LB2 from the medium surface and the reflected light LB2 transmitted through the recording layer 3 and reflected by the reflecting film 2. The refractive index in the air is designated as n1 and the refractive indices of the medium as n2 (before the irradiation of light) and n3 (after the irradiation of light), then n1/n2=sinphi1/sinphi2, n1/n3=sinphi1/sinphi3 hold. Since the phi2, phi3 can be detected by determining the phase difference between the LB2 and the LB3, the difference between the refractive indices n2 and n3, i.e. the detection of information, is possible. The optical recording and reproducing system which can reproduce the information without erasing the information and utilizes the photochromic material is obtd. in this way.