The principle of confocal microscopy is quite simple: shine focused light on the sample and collect the intensity of the reflected light. The reflected beam is separated from the path of the incoming light via a (polarizing) beam splitter.

All we have to do to get an image is to move the sample with respect to the light spot, and of course make sure it stays in focus.

So where does the BluRay come into all of this?

It turns out that CD, DVD, and BluRay drives use exactly this principle to read your music/movies! (To first order approximation at least...).

As you can see from the picture there is a few more components, not just a laser, a beam splitter, a lens, and a sensor. Those additional components are basically there to improve the quality of the beam and are suitably well engineered that we can more or less ignore them (for now).

(Picture adapted from repairfaq.org)