| 摘要 |
PCT No. PCT/JP90/00843 Sec. 371 Date Feb. 21, 1991 Sec. 102(e) Date Feb. 21, 1991 PCT Filed Jun. 28, 1990 PCT Pub. No. WO91/00596 PCT Pub. Date Oct. 1, 1991.An optical disc apparatus includes an optical disk which satisfies the relationship of (Ascos phi s - 1) >/= -Ds(As2 - 2Ascos phi s + 1)2/4 lambda 2 or Ascos phi s = 1 where As, phi s are the amplitude reflectivity ratio and the phase difference between the regions within and out of a signal mark (27, 28) on a signal surface (16) of the optical disc, Ds is the area of the signal mark (27, 28) and lambda is the wavelength of a light source (8), and the light reflected from signal surface (16) is input-coupled by a grating coupler (4A, 4B) into a waveguide layer to propagate as wave-guided light (18A, 18B), radiated at the end of the wave-guiding layer (3A, 3B) and received by a light detector (6A, 6B) so that a control signal and a reproduced signal can be obtained from the detector.
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