OPTICAL PICKUP COMPATIBLE WITH CD-R AND DVD USING ROUND SHIELD SURFACE

摘要

PURPOSE: An optical pickup compatible with a CD-R and a DVD using a round shield surface is provided to adopt a round diaphragm having the round shield surface capable of selectively controlling numerical apertures according to beams having different wavelengths, so as to remove a spherical aberration generated during disk compatibility. CONSTITUTION: The 650nm wavelength beam emitted from a light source(31) is transmitted to the first hologram beam splitter(32). The transmitted beam is incident on a beam splitter(33). The beam splitter(33) transmits all 650nm wavelength beams, and totally reflects 780nm wavelengths. A beam transmitted through the beam splitter(33) passes through a collimating lens(34), and is transmitted to a round diaphragm(40). A 780nm wavelength beam emitted from a light source of a laser diode unit(37) is transmitted to the second hologram beam splitter(36). The transmitted beam is incident on the beam splitter(33). The round diaphragm(40) compensates a spherical aberration generated by the 780nm wavelength beam of the laser diode unit(37).