STM Calibration

STM Cal. tab allow user to adjust calibration data for tunneling mode of SPM operation.

• Max It, nA - maximum tunneling current. This value depends upon a sample table that is used (with hi or low sensitivity). This value can be calculated fom following equation: $I_t=U_t/R_t$,where $R_t$ is sample table resistance.
• Max Ut, V - Maximum voltage on the tunneling gap.
• Inverse feedback - sign of a feedback. With positive feedback incriase in error signal leads to increase in feedback signal, with negative feedback - increase in error signal leads to decrease in feedback signal. In STM mode positive feedback is used.
• Inverse It - Error signal sign. In STM head inverting operational amplifier is installed. So the error signal come to ADC in inverted form.
• Feedback channel - channel of 1-st ADC, from which feedback signal is taken. At the present moment 0 channel is used for error (deflection) signal, and 1-st channel used for RMS signal (which is used as feedback signal in Resonance AFM mode)