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.