It's a phase change alloy, when writing a high powered laser is used to melt the alloy, when it cools quickly it becomes opaque. When erasing, a lower powered laser heats up the disc and returns it to its transparent state. A reading laser isn't powerful enough to change the phases at all. So, you have the idea right... just no magnets involved.
It's a phase change alloy, when writing a high powered laser is used to melt the alloy, when it cools quickly it becomes opaque. When erasing, a lower powered laser heats up the disc and returns it to its transparent state. A reading laser isn't powerful enough to change the phases at all. So, you have the idea right... just no magnets involved.