The laser diode is the heart of the CD player, responsible for reading the data stored on the disc. Let's take one apart and get it going as a stand alone laser. It can be used for future projects not limited to light shows, laser engraving, games and experiments. As you can see, a laser beam shoots from the diode towards the prism, which. Laser diodes can "deteriorate" over many hundreds or thousands of hours use. Deterioration here meaning a reduction in optical output for a given current.