Interferometric cantilever detection

Detection of cantilever displacement is another important issue in force microscope design. The first AFM instrument used an STM to monitor the movement of the cantilever—an extremely sensitive method. STM detection suffers from the disadvantage, however, that tip or cantilever contamination can affect the instrument s sensitivity, and that the topography of the cantilever may be incorporated into the data. The most coimnon methods in use today are optical, and are based either on the deflection of a laser beam [80], which has been bounced off the rear of the cantilever onto a position-sensitive detector (figme B 1.19.18), or on an interferometric principle [81]. 

Electrocapillary curves of various metals under different conditions have been determined with the bending plate technique 1158,159], The deflection of the plate is usually measured by an optical lever. Pangarov and Kolarov used an interferometric method to detect the bending of the plate I60]. Recently the method was improved by using microfabricated cantilevers 1161-163). Bard et al. glued flat metal 1164,165] or semiconductor 1166] electrodes onto piezoelectric disks. When applying a potential to the electrode the resultant bending caused a potential on the piezo, which was detected. 

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