Patent ID: 9599636
Date: 2017-03-21
CPC Classifications: G01Q

Claim:
1. A scanning probe microscope comprising: a probe that is mechanically responsive to a driving force; a signal generator for providing a drive signal to an actuator that generates the driving force by heating the probe, the drive signal being such as to cause the actuator to move the probe repeatedly towards and away from a sample; a detection system arranged to output a detection signal indicative of a position of the probe; and signal processing apparatus arranged to monitor the probe as the probe approaches the sample and to detect a surface position at which the probe interacts with the sample; wherein in response to detection of the surface position the signal processing apparatus prompts the signal generator to modify the drive signal to cause the probe to move away from the sample, wherein the signal generator is arranged so that the drive signal comprises a series of cycles, each cycle comprising an approach phase in which an intensity of the drive signal increases to a maximum value to heat the probe and cause the probe to move towards the sample; and a retract phase after the approach phase in which the intensity of the drive signal reduces from the maximum value to a minimum value in response to the detection of the surface position so that the probe cools and moves away from the sample, wherein the signal generator is further arranged so that the intensity of the drive signal is held at the minimum value during the retract phase and then increased at the end of the retract phase, and wherein the signal generator is further arranged so that the duration of the retract phase for each cycle is dependent on the maximum value in the approach phase of that cycle so that a high maximum value is associated with a long retract phase and a low maximum value is associated with a short retract phase.