CD. Printed label. Pits and lands.

Images made through a microscope. All subject types.

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Charles Krebs
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Joined: Tue Aug 01, 2006 8:02 pm
Location: Issaquah, WA USA

CD. Printed label. Pits and lands.

Post by Charles Krebs »

I picked up an Olympus Neo DPlan 80/0.80 at a very low price. (A little beat up on the tip, but the glass looks to be unscathed). Previously I've looked at a CD in epi-darkfield with the 20X. (No need to "disassemble it" since there is adequate working distance with the 20X to see through the plastic). After Gerd posted his excellent CD/DVD comparison a while back, I've wondered how the "pits and lands" would look under higher mag darkfield. This time I needed to peel off some of the material since the short working distance of the 80X will not allow imaging through the plastic.

But before I even got to that subject I was intrigued by the way the screened on "label" looked under the various types of epi illumination. I thought others might find it interesting as well. So the first three shots are of the printed back surface of the CD (all taken at 50X on sensor).

The first is epi-DIC.
Second is brightfield (with crossed polarizers)
Third is epi-darkfield.




I had broken apart the CD and scraped some of the pieces with a razor in order to gain access to the layer that contained the data. This next image shows a part where the layers broke off, but some still adhered to the underlying surface. First is the painted plastic rear surface (on the left). Then there appears to be the reflective layer (but it actually appears clear here :smt017), then below that is the layer that (I think!) is the actual data layer. This was with brightfield and crossed polarizers.


Finally I found a nice clean section, and got the epi-darkfield image of the data pits and lands. (This was 200X on Canon 50D sensor... 80X objective and 2.5X NFK photoeyepiece)

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Post by SiBurning »

Glad to see this.

I was just looking at a CD and vinyl record the other day, thinking of bringing a microscope to a stereo meet. Couldn't get a good enough image in the eyepiece. Seeing all the trouble you went through to get this online... well...


and I don't feel so bad now. :D

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Joined: Sun Aug 15, 2010 1:43 pm

Post by Mitch640 »

That's pretty interesting. I also tried viewing a CD after Gerds thread, but got nothing.

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