In article <3dv3ts$7de@planchet.rutgers.edu>, palmer@alumni.caltech.edu (David M. Palmer) writes:
> chensung@ux5.lbl.gov (Sung-wei Chen) writes:
> No it doesn't need expensive circuitry nor a vacuum system.
> The magazine 'Computers In Physics' had an article about an
> easy to build STM about 5-8 years ago. Vibration isolation was
> done with bungee cords. There was no 'inchworm' drive for coarse
> positioning so it had a limited field of view, but it still looked
> pretty good. I am mechanically inept and it looked like the
> sort of project I would be able to do.
That was the Jul/Aug 1990 issue of Computers in Physics, page 427, "A Scanning Tunneling Microscope For Undergraduate Laboratories" by R.K. Sears, B.G. Orr, and T.M. Sanders, Jr. of U of Michigan, Ann Arbor.
They give only a block diagram of the circuitry, but do give several useful references. About the only "major" change I would suggest for the amateur scientist with a MS/DOS PC is to buy an inexpensive Soundblaster 16 compatible audio card. These come with two 8/16 bit A/D ports and two 8/16 bit D/A ports suitable for acquistion up to audio frequencies. Unfortunately, the only book I have on programming Soundblaster cards ("The Soundblaster Book" by Josha Munnik and Eric Oostendorp, Sybex 1994) covers only 8 bit AD/DA for the standard Soundblaster card. If anyone knows of a better reference on sound cards, please let me know. The alternative is to purchase a more expensive AD/DA card from a "real" data acquistion card manufacturer.
They hung the entire microscope from the ceiling by elastic cords (1-Hz resonance) to isolate the system.
The design was meant for a student lab where, according to the authors, "The philosophy of the course is not to emphasize the final operation of the instrument, but to concentrate on the steps necessary to build research apparatus."