Deflection limit

giampa posted on Wed, May 29 2013 11:43 AM

rated by 0 users

dear AFMers,

we seem to have a problem on our NS IIIa/multimode/picoforce with the deflection measurement. It apparently works fine detecting lever deflections in the range -1.25V to 1.25 V, with 'deflection limit' set to 2.5 V, but setting Deflection limit to 20 V simply rescales the data badly, but does not really extend the range for the measurement of the deflection, which still saturates if the 'real' deflection (read on the meter in the head) goes outside the +-1.25 V range. When used in imaging mode, the machine works fine, as it is in feedback and the deflection stays constant. On the other hand, doing force-curves, the deflection can change a lot and saturates easily.

Where in the hardware is the control for the 2.5-20 V amplification setting for the deflection read-out? could it be that an OpAmp or similar just burned? Any suggestions?

best regards and thanks,

giampaolo