Sony DVP-NS300 Training Manual

Also see for DVP-NC655P: Manual Limited warranty Servise manual Operating instructions Specifications

31. What’s New?Dual Laser Optical BlockDisc Playback CharacteristicsAll fifth generation DVD models, (except basic model DVP-NS300) can play back computer made –R or +RWdiscs.Computer made (burned) –R or +RW discs have different characteristics than machine stamped counterpartsand stamped CDs have different characteristics than DVDs. To insure full compatibility, the optical block usestwo lasers. One is optimized for CDs and the other for DVDs.To understand how separate lasers insure playback of computer burned discs, some basics are explained here.The reflected Laser light from the disc to the optical block contains the data. DVD discs (including DVD-R and+RW discs) reflect best in the 650-635nM wavelength band. CD discs (including –R or +RW discs) reflect lightbest at 780nM.Figure 1-2 shows that maximum CD-R disc reflection (RF) occurs at 780nM. Since –R or +RW discs have lowerreflectivity than stamped discs (reflectivity also varies from brand to brand) output is maximized if two lasers areused: one operating at 648nM for DVDs and another at 780nM for CDs.Optical Pick-up650nM 780nM WavelengthReflectiveIntensity forCD-RFor DVDCD = 1.2cmDVD=0.6cmFor CDLensKHM-240FIGURE 1-2