| 摘要 |
PROBLEM TO BE SOLVED: To perform stably control for keeping constant the distance between a sample and a probe of a cantilever even at the high-speed scanning time, in a slope detection system in an AC mode. SOLUTION: A voltage signal wherein a displacement detection signal of the cantilever 1 from a piezo element 4 for detection is the amplitude quantity of the displacement detection signal by RMS 11 is outputted. An error amplifier 12 outputs an error signal between the voltage signal and a reference voltage. The error signal is inputted respectively into two kinds of the first and second low-pass filters 18, 19 with an optional gain by a gain 13. The error signal is changed into an error signal having two kinds of time constants of an error signal having a small time constant by the first low-pass filter 8 and an error signal having a large time constant by the second low-pass filter 19. Feedback control in the Z-direction is changed into double feedback control between control by the potential of the piezo element 4 for detection based on the signal having the small time constant and control by a Z-piezo scanner 6 based on the signal having the large time constant, and feedback control in the Z-direction can be performed stably at the high-speed scanning time. COPYRIGHT: (C)2005,JPO&NCIPI
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