LASER diffraction off a CD-ROM

I recently took a photo of LASER diffraction off a CD. Some of my friends (and I) liked it, so I thought it should appear on my blog as well. So here it is:

I’ve labelled the various beams that you see in the photograph in this version:

Trivia: Why is the second maximum beam (n=2) brighter than the first maximum beam (n=1)?

I was able to roughly estimate that the CD’s tracks are about a micrometre apart and that the pits containing the data are either further apart than that, or show a regularity on a larger scale than that. Need to do some more qualitative experiments on that.

The photo is a 15 second exposure at f/3.5 @ ISO 1600. Released to public domain. Credits requested.

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