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(Re-)building a Scanning Tunneling Microscope (STM).
We are currently in the process of getting an STM back up and running. The hardware was inherited from a past project by one of our members, where it successfully imaged sample surfaces. Now we are trying to improve on those past results.
[Current working state of the experiment]
Links
STM key information
Mechanics
STM Mount
The STM mount consists of two aluminum plates which seat against each other precisely using a kinematic mount made from 3 micrometer screws.
The tip/probe is mounted slightly in front of two of the screws with the last one sitting very far back. This makes a fulcrum with the back screw having even more fine adjust (factor 20).
Thread pitch of micrometer screws (according to lab book 16.3.2012):
- Front 0.25mm per revolution
- Back is hence 0.0125mm per revolution or 12.5µm
Vibration isolation
We have built ourselves a simple passive vibration isolation using tension springs and a large mass. The intended damping element (an eddy current brake) did not end up working, but also wasn't really needed after all.
We have not measured performance, but the real world resonance frequency matches the calculations quite well. Here is the calculated transmissibility (blue curve):
Electronics
Learn more about the electronics here: https://git.fa-fo.de/fafo/k8ik-stm/src/branch/main/Electronics
Piezos
Other Projects
There are quite a few other DIY/open STM builds out there. Here are a few links for further reading: