OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE

• Main Author: EMOTO KENGO
• Format: Patent
• Language: English
• Published: 26.01.2001
• Edition: 7
• Subjects: CALCULATING; COMPUTING; COUNTING; HANDLING RECORD CARRIERS; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS; PRESENTATION OF DATA; RECOGNITION OF DATA; RECORD CARRIERS

PROBLEM TO BE SOLVED: To make stable information reproduction possible by providing the above device with two light sources; a light source for recording and a light source for reproducing and forming the higher order diffracted luminous fluxes of second or higher order obtained by diffracting the luminous flux from the light source for reproduction with a diffraction grating as a luminous flux for reproduction of information. SOLUTION: The P polarized luminous flux emitted from an LD 63b for reproduction is collimated by a collimator lens 63b to nearly parallel luminous fluxes which are made incident on the diffraction grating 65 and are divided into the higher order diffracted luminous fluxes of the zero order luminous flux, ±1st and ±2nd order or above. The diffracted luminous fluxes of the zero order luminous flux and 1st order formed by the diffraction grating 65 pass a dichroic prism 64 and a polarization beam splitter 66. The luminous fluxes are imaged as light spot on the information tracks and tracking tracks on an optical card C through a bending mirror 27, a quarter-wave plate 28 and an objective lens 29. The light beams cast onto the optical card C are reflected again at this card and are respectively projected again at a photodetector 74 through a detection optical system 30 through the objective lens 29 and the quarter-wave plate 28.