2 Photoactivated atomic force microscopy with 2nd harmonic response

摘要

The present invention relates to a photoactivated atomic force microscope with ultra high resolution using second harmonics. The photoactivated atomic force microscope comprises: a photoactivating light providing unit to focus a pulse laser beam of a preset reference frequency on a prescribed position of an object board to provide the pulse laser beam to thermoelastically expand samples; a cantilever having a cantilever tip on an end thereof; a signal detection unit to detect and provide a signal corresponding to a position of the cantilever tip changed by vibration of the cantilever tip; a lock-in amplifier module to detect a first harmonic signal and a second harmonic signal from signals provided from the signal detection unit to output the first and the second harmonic signal; an image signal processing unit to use the first and the second harmonic signal provided from the lock-in amplifier module to generate a first and a second ultra high resolution image for each sample; and a microscope controller to control movements of a transport stage and the cantilever. The cantilever tip comes in contact with the surface of the sample by control of the microscope controller. Optical properties for the sample are detected by sensing a movement of the cantilever tip by thermoelastic expansion of the sample. The second ultra high resolution image using the second harmonic signal has better contrast than the first ultra high resolution image by the first harmonic signal to improve resolution.