- #1
Charles123
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I read things like "When a dual layer DVD burner reads a dual layer disc, the read-laser readjusts its focus past the semi-transparent first layer of physical data, on to an additional layer of data." and "Reflectivity of both recording layers of a dual layer recordable disc is the similar: greater than 18 percent. The reflectivity between the L0 and L1 layers, however, is greater than 50 percent because the upper (second) recording layer absorbs and reflects some of energy that is directed at the lower (first) recording layer L0 in order for organic dye to be recorded.". Ok, so the first layer is semi-permeable, but how does the signal differentiates what is reflected by one layer from what is reflected by the other layer? I imagine, and this applies to a single layer DVD or CD, in the differentiation between lands and bumps that the refractivity in the polycarbonate layer allows the reading or not reading (0 or 1) of the reflected signal - "The laser beam passes through the polycarbonate layer, reflects off the aluminum layer and hits an opto-electronic device that detects changes in light. The bumps reflect light differently than the "lands" (the rest of the aluminum layer), and the opto-electronic sensor detects that change in reflectivity. The electronics in the drive interpret the changes in reflectivity in order to read the bits that make up the bytes."; and therefore I assume that it may also play a part in detecting from witch layer it is reading.
Can someone elucidate me on this? And please correct any wrong assumption that I may have made!
Thank you
Regards
Can someone elucidate me on this? And please correct any wrong assumption that I may have made!
Thank you
Regards