optical technology, media ordering information, cd mastering, dvd mastering, blu-ray mastering, single layer optical media, bd rom optical media, bd-r dl optical media Search      About OM&T Products Test Discs About Test Disc Test Disc Products - Products Overview - Products Catalogue - Terms & Conditions Philips Blu-ray Test Disc Range Special CD/ DVD Ranges Media Ordering News Center Job Opportunities Contact      Home  -  Products  -  Test Discs  -  Test Discs Products  -  Products Overview     Products Overview Back Physical Defects Physical defects are generally defects arising during the manufacturing process.      Eccentricity This relates to variations in the distance between the geometrical center of the data track and the center hole of the disc. For example the specified eccentricity is ±70 µm for CDs. Higher eccentricities can cause playability problems because of tracking errors. Damage introduced by the user can also be compounded by excessive eccentricity.      Thickness Disc thickness is important because the spherical aberration (inability of all rays tofocus at the same point) depends on the thickness of the substrate. The optical path is designed for anominal thickness of 1.2 mm, so thickness variations will increase the spherical aberration. Thinner and thicker discs − varying from the nominal specification by ±0.1 mm − allow drive or player robustness to variations in the substrate thickness to be checked.     Vertical deviation Vertical deviation is defined as the movement which the actuator has to make to follow the tracks correctly as the disc height varies. By means of height deviations the test disc activates the actuator, the focus servo loop.      Angular deviation Angular deviation is the angle between a parallel incident beam and the reflected beam, including deflection due to the entrance surface and unparallelism of the recorded layer. The maximum angular deviation is defined as 0.80° in the radial direction and 0.30° in the tangential direction. Defects Explained Physical defects Semi-physical defects Electronic/optical defects Custom discs       © Copyright 2008, all rights reserved with Moserbaer Optical Storage designed by: cross section

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