AN X-Y SCAN GENERATOR FOR A SCANNING TUNNELING MICROSCOPE

The design and construction of a digital X-Y scan generator used in co njunction with a scanning tunneling microscope and a data acquisition card for the purpose of digitizing images are presented here. The unit generates triangular waveform voltages for the piezoelectric elements and equally spaced pulses in the X and Y directions. The ''nXn'' trig gering pulses are used to initiate digital to analog conversions in a data acquisition card thus obtaining a symmetrical digitized image. Th e generator is well suited as a scan generator for any lab-built tunne ling microscope.