1. R.J. Muha, S.M. Gates, P. Basu, J.T. Yates Jr., Rev. Sci. Instrum. 56, 613 (1985)
2. Model 2B50B, obtainable from Analog Devices, One Technology Way, Norwood, MA 02062-9106
3. Model UDC 500, obtainable from Honeywell, Micro Switch Division, 11 W. Spring Street, Freeport, IL 61032-4353. More advanced controllers are now available from Honeywell, such as the UDC 5000 ultrapro
4. M.A. DeAngelis, A.B. Anton, J. Vac. Sci. Technol. A10, 3507 (1992)
5. LabVIEW is available from National Instruments, 6504 Bridge Point Parkway, Austin, TX 78730-5039, USA