Yasuyuki Kanou

Dvd/cd/cd-r Compatible Pick-up With Two-wavelength Two-beam Laser

The CD-ROM and CD-R (recordable CD) playback compatibility is in great demand for DVD-ROM disc drive devices. The authors developed a new optical mechanism that utilizes a holographic optical element with wavelength selectivity, and two-wavelength two-beam laser in order to produce a DVD/CD/CD-R playback compatible pick-up with one objective lens.

Beam shaping for detection of small object by phase correction element

The spat size is determined by the wavelength of the laser and the numerical aperture (NA) of the objective lens. So it cannot be below the diffraction limit. There is, however, a method of increasing the resolution of an ideal optical system by varying the state of the laser light that enters the objective lens. This is a kind of super-resolution. That method, however; generates side-lobes, which are a characteristic of super-resolution. We report a method of eliminating the effects of side lobes through beam shaping. We evaluated the data reading characteristic for when the phase correction element was applied to an optical disk.