According to crash this is impossible?
Look, it's a simple matter of optics. CD-ROM's read by bouncing a laser of wavelength
w at a reflective disc rotating k*w distance away. Data is encoded onto the disc by depressing the reflective surface such that it is moved k*w+1/2w away from the laser, so that as the beam returns from the reflective disc, it's 180 degrees out of phase and so the beam cancels itself out. A simple photodiode detects the difference between the beam being reflected and the beam being out of phase.
Shooting the beam through a transparent disc to try to detect some biological colony isn't going to work,
because there's no photodetector above the disc in a CD-ROM drive. And even if there were, what's the point of this? The best you get is a picture of a disc with fungus growing on it, and you can get that from putting it on a flatbed scanner.