Abstract
The distance between sample and probe in a scanning near-field optical microscope is regulated via tracing the shear-force on the tip which is glued to a tuning fork piezo. A lock-in technique is used. We demonstrate that the bandwidth of the control loop is increased if not only amplitude or phase, but a favorable combination of both is used as feedback signal. The enhancement of bandwidth is connected with a reduction of signal-to-noise ratio. The optimum combination of both, bandwidth and signal-to-noise ratio, can be adjusted purely electronically to the specific needs of an experiment. A theoretical model is developed that discloses the relation between the mechanical and electrical properties of the combination of tuning fork and fiber tip. The frequency response of the shear-force detection system is calculated with a numerical simulation based on this model. Experimental frequency response curves are well fitted by these simulations. Our results are especially important for low-temperature scanning microscopy, where the bandwidth enhancement is essential for obtaining a reasonable scanning speed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
