Optical recording/pickup head compatible with a digital versatile disk (DVD) and a recordable compact disk (CD-R) using a holographic variable aperture

摘要

An optical recording/pickup head having compatibility with a recordable compact disk (CD-R) and a digital video disk (DVD) transmits a first light beam having a wavelength of 635 nm for a DVD emitted from a first light source and a second light beam having a wavelength of 780 nm for a CD-R emitted from a second light source to an objective lens, using a holographic variable aperture. The holographic variable aperture totally transmits the incident first light beam to the objective lens, and transmits part of the incident second light beam to the objective lens. The objective lens focuses the incident first and second light beams on the information recording surfaces of the CD-R and the DVD. The sizes of the light spots which are focussed on the information recording surfaces of the DVD and the CD-R by the objective lens are approximately 0.9 m and 1.4 m, respectively, which appropriate for recording and reproducing the respective disks. The light spots have only a main lobe.