Veeco AFM Board

I had this PCB from an old Veeco Atomic Force Microscope (AFM) sitting in my junk box. An AFM is capable of sub-nanometer resolution imaging. This is much better than the few hundred nanometers you can achieve with an optical microscope or 10s of nanometers generally achievable with optical super resolution microscopy.

With sub-nanometer resolution, you can potentially resolve individual atoms. Over on my other newsletter I generally look at approaches analyzing DNA. A few of these are based around directly detecting single molecules. So I picked up some old AFM parts on eBay a while ago to play around with (you can find full teardown pics here).

Generally AFMs are described as using a tip to touch a surface. This brings up all sorts of complicated questions like “what does touching mean anyway?”. But it seems like as good an analogy as any…

A nanoscale tip moves along the surface, feeling out features. A laser is reflected by the backside of the tip, which is attached to a sprung cantilever. As the tip moves up and down the reflection is registered on a quadrant photodiode (much like a optical disc read head), and therefore provides feedback on the tips motion.

Generally the sample is on a piezo driven stage, which lets you move it in X,Y and Z with sub-nanometer precision.

Looking at the PCB, Veeco had removed the markings for a few of the chips. I thought it would be fun to pull the caps off these and image a few of the chips:

The middle IC seems to be the AD534 an “Internally Trimmed Precision IC Multiplier”. I manually stitched together the die image shown below, which is from my old epi-illumination rig. Rather handily the datasheet also includes a mask image, which is an exact match.

A quick google search failed to identify the “left” and “right” ICs from their markings alone. In the time I had, that’s as far as I got with this PCB, so for the moment back in the junk drawer it goes.

But stay tuned! Someday I might revisit it.

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