A Compact Disc-Recordable Compatible Digital Versatile Disc Pickup with a Lens for 780 nm and 650 nm Wavelengths

Two types of compact disc-recordable(CD-R) compatible digital versatile disc (DVD) pickups have been developed. One has separate conjugate points for DVD and compact disc(CD) readouts. The other has a common conjugate point for DVD and CD readouts. Optical and signal properties are considered for both types. Both types have been shown to exhibit good qualities for practical use.