OPTICAL REPRODUCTION DEVICE

• Main Authors: SANO SHOJI, SUGAWARA MAKOTO, YOSHINAGA CHIKASHI, OKUBO TATSUO, NAKAZATO YASUHIRO
• Format: Patent
• Language: English
• Published: 31.07.1997
• Edition: 6
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

PROBLEM TO BE SOLVED: To prevent the degradation in reading accuracy based on the double refraction of the transparent layer of a recording medium by setting the polarization direction of a reading light beam at a specific direction with respect to the flow direction of a material in injection molding of the transparent layer. SOLUTION: The transparent layer of a disk 4 is formed by injection molding of a resin, such as acryl or polycarbonate. the resin is supplied from a central gate. The optical anisotropy of a circumferential direction (x) and a radial direction (y) arises in consequence of the radial flow of the resin. The light beam from a semiconductor laser 1 arrives at the signal surface of the disk 4 through a half mirror 2 and an objective lens 3. The reflected light subjected to modulation is inputted through the objective lens 3 and the half mirror 2 to a photodetector 5. The p-n junction surface of the semiconductor laser 1 is arranged in a direction (x) in the photodetector to align the direction of the linearly polarized light of the irradiation light on the signal surface of the disk 4 to the radial direction (y) of the disk 4. As a result, the generation of a phase difference component in the light beam passing the optically anisotropic transparent layer is suppressed.