Question: How do DVDs work?
Answer: Yeah, you've thought about it before. You've popped a movie into the player and thought about how amazing it was that that little disk could play entertainment for you.
Strictly speaking, a DVD is just a CD with more space on it. The data on the disk is encoded in little valleys and bumps on the surface. The reason you can't feel those little imperfections on the surface is because during their production, they're covered with a few layers of polycarbonate plastic.
 |
A scanning-electron-microscope image of a DVD. See the
bumps? That's your movie. (PC: optics.rochester.edu) |
You can't see them, either, because a reflective layer (which I assume is the back of the DVD that we know so well) is put over them, covering them.
Essentially, the data on a DVD is bundled into an extremely long, condensed spiral of data. Your DVD player is designed to read the bumps on the spiral of the DVD.
So your DVD is basically a prettied-up coiled string of data with plastic around it. Doesn't sound all that fancy, right? It's actually more complicated than I summarize it to be, as you've already found by reading above.
Just a heads-up: The string is something like 740 NANOmeters thick. And just letting you know, 1 meter is 1,000,000,000 nanometers. The wavelength of red light is 650 nanometers. So your DVD's data is only slightly thicker than a
wave of light. That's
really small!
If you want to learn more about DVDs and how they work, click
here.
