The laser-equipped Lego train

In a previous post I was not very happy with the results of my opto-acoustic capture of the miniature gramophone record, so today I thought I'd try to illuminate the record surface more evenly.

Of course, the straightforward solution is to build a circular LEGO® railroad track around the record and have a laser-hauled train run around the track, illuminating the record surface with coherent light at a constant tangential angle, while a camera captures the image at long exposure.

This time I didn't want to go through the trouble of positioning the high-resolution camera and only got this:

I learned that Lego is not very good for laser work in general; specifically the trains don't run very smoothly, as you can see in the above pic. Updates with audio will follow, anyway. In the meantime, here's a video.

Bonus points if you can hear what's happening in the background.

Update: I didn't post an audio update, because the audio was useless. And the whole laser thing was a dead end anyway. Instead, I edited the high-res photo I took earlier, removing the extreme shadows using Gimp's Dodge/Burn tool, then changed my Perl code a bit so that it actually stays on track, and made this:

Now I can put the robot back together and close this case.