What's new?

Hopefully I'll get around to update this site occasionally. It's supposed to reflect a reasonably up-to-date state of my project. The most recent changes, as well as developments or questions that have not made it to the regular pages yet, will be summarized here.

In the main pages, recent changes will be highlighted like this [New!].

April 17, 2006


Some updates to the web pages:

  • Fixed an embarassing number of dead links and outdated information on the References page.
  • Added information on tip preparation on the Applications page.
  • The Mechanics page now has mechanical drawings (in poor quality) of my homebrew design.
  • Added a link to GSXM, an impressive software package for acquiring and analysing STM images (among others), to the Software page.
Still no images from my STM, but I have just set it up again after moving house...
May 5, 2004


Just a short hint that this project is not quite abandoned yet. I seem to find time to work on it about once a year, for a few days... In the meantime, the DSP has learnt to transmit image data, so the only essential component that's missing is the PC software to receive those images. Next year? ;-)

October 27, 2002


While I have updated some links on this site occasionally without mentioning it here, today's update warrants a separate announcement: Two new links to working home-built designs in the Reference section - Joseph Gatt's amateur STM and an STM for schools developed at the University of Münster.

On the software page, an update on free image processing programs for post-processing of scanned images. - While my own project has been idle for the best part of two years now, I still intend to finish it. Just took up the specification of the serial communication 'protocol' again, for transferring the scanned data to the PC. More on this soon?

April 23, 2001


We're back! After more than two months of downtime due to a very lengthy transition to another web hosting service, the STM pages are finally back up and running. Sorry about any inconveniences caused by this unexpected outage! No changes in the pages (or the state of affairs of my STM project itself) yet - but I will get around to writing that software eventually!

September 2, 2000


Hardly any progress of the STM itself during a long spring/summer hiatus. Today's update to the web site is meant to reach a consistent description of the current project state on the various pages again: I added some experimental results for the actual tunneling current amplifier and images of the vibration isolation; and updated the status description, downloadable software and GAL logic code, the budget, and some minor details. Also fixed several bad links in the reference section and elsewhere. (Hope I found them all!)

Unpleasant news from Motorola: They have discontinued the DSP56002 evaluation board used in this project, "due to lack of availability of memory components required for this product". The 56002 processor itself still is an active product, although the 3.3V version will be discontinued. No direct successor to the 56002 evaluation kit seems to be available; the DSP56009 kit looks more complex and expensive, and I have not looked into compatibility at all. You may be able to pick up leftover DSP56002 evaluation kits from dealers or distributors.

January 9, 2000


New link to John Alexander's STM, an amazingly simple amateur design using John's unimorph disk scanner, on the Reference page. A short paragraph on the disk scanner has also been added to the discussion of piezo geometries, but I really recommend John's explanation on his site.

Some small updates reflecting my progress: A short paragraph on the vibration isolation I use, some information on the DSP software I wrote to drive the STM, and minor revisions to the circuit diagrams.

Current status:
The DSP software has made more progress. The feedback loop is working, and the STM can now automatically and reliably establish tunneling current (without crashing the tip in the process). Unfortunately, I can't obtain any images yet, since that requires additional software on the host PC side to be written. - On the hardware side, I'm not quite happy with the feedback loop's performance yet; more noise and more phase delays than expected. While the tunneling current amplifier has now been moved from its prototyping board to the STM head, I still did not get around to update the electronics section. Next time?

December 6, 1999


Update on AngstromTools on the Reference page. Fixed a few links on the Reference page as well. Included a section on ImageJ, and updated the link to the ImageTool site on the Software page.

I have started to work on the DSP software, but don't think it's stable enough to put anything on the web site yet. Serial I/O, a simple command interpreter, stepper motor control and scan generation via the Codec on the 56002 evaluation board are working. The most important part that is still missing is the Z feedback loop.

Also, I finally tried to actually build my tunneling current amplifier - and found that things are not quite as easy as my calculations suggested, of course. I hope to add an update on noise and stability, based on actual experimental results, in the electronics section soon...



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