Two scanning tunneling microscopes (STMs) operating in air were design
ed for imaging samples with dimensions up to 75 mm diam and 25 mm thic
kness. Both STMs allow a wide sampling range capability to be obtained
by means of xy sample positioning stages spanning 25 mm with 0.1 mum
resolution. The automatic tip-sample approach is achieved in the two d
evices by moving either the head scanning stage or the sample bolder.
These STMs were successfully used to image highly oriented pyrolithic
graphite, gratings, and indentations made on hardened steel.