Does the laser on my CD player read the CD from the outside in (like a stylus on a record player), or from the inside out?
The information stored on a CD: is it stored on the outside of the disk, with blank space in the middle, or vice-versa?
Finally: when my CD burner burns a CD (or when the machinery at the factory does it), does it burn from the outside in, or from the inside out?
A CD player/burner works from the inside towards the outside on a continous spiral track (just like vinyl records, except in the opposite direction).
The blank space is on the outside of the disc. If you look closely at an already-burned CD-R (or DVD-R) that’s not completely full, you can see a line where the burn stopped. The spiral track around the disc onto which data is written is 0.5 microns wide.
Factory-made CDs aren’t burned. That’d be much too slow for mass production.
They’re mechanically pressed in a mold, much like vinyl LPs were. One smoosh and the entire CD is done. Then a protective outer layer is put over the pressed dents and the whole thing heated to fuse the cover onto the substrate.
The data on a CD is actually just under the label. The rest of the disc’s thickness is due to a protective layer of plastic.
Sorry, not quite. The polycarbonate substrates are molded as you describe, the data layer is metallized with a thin layer of (usually) aluminum - about 50-70 nanometers thick, then the metallized data layer is spin-coated with a layer of liquid UV-curable resin called lacquer - about 5-12 microns thick. The disc is exposed to very high energy radiation for 1-2 seconds and the lacquer is cured.
The finished discs then go to be printed.
Should be: very high energy UV radiation