I started with a paper clip on the CDI moved in as close as I could. You can see the blurred edge of the paper clip at the top.For comparison, here’s a piece of my hair, poorly shot because the depth of field is so limited at this magnification. Also I haven’t mastered the layering function as yet.Average hair width is ~ 100 µm or 0.1 mm. Those holes on the CD are tiny indeed.
More info from Wikipedia – The pits in a CD are 500 nm wide, between 830 nm and 3,000 nm long and 150 nm deep. 1000 nm = 1 µm