CDs are dying. It’s an unfortunate but inescapable fact as the world transitions to digital downloading. But while the end may be in site for CDs and DVDs, it hasn’t come yet. Before that day actually comes, perhaps we should take a quick look at this awesome technology and how it works.
A CD’s base a a polycabonate plastic material that is transparent. It provides the structure and protection for the layers above it. Above the polycabonate is a thin layer of aluminum reflective coating followed by another thin layer of crylic and then the label. The most important part of a CD is that the polycabonate sheet is imprinted with a series of miniscule bumps. The details of the bumps is a code that is what stores the data on the disc. The bumps move outward from the center of the CD in a spiral pattern all the way to the edge. The CD reader move along this track using a precise laser to detect the changes in the bumps and decode the data stored on the CD.
As CDs become less and less useful, perhaps we need to find other uses for them. One entertaining DIY science trick we can do is to melt part of the polycarbonate sheet and blow it out to create a giant bubble. Make sure to scrape off the aluminum sheet or else it won’t expand to its full amount. Enjoy!