ANITA—An active vibration cancellation system for scanning probe microscopy

Abstract

The high sensitivity of scanning probe microscopes poses a barrier to their use in noisy environments. Vibrational noise, whether from structural or acoustic sources, can manifest as relative motion between the probe tip and sample, which then appears in the probe position ("Z") feedback as it tries to cancel this motion. Here we describe an active cancellation process that nullifies the appearance of this vibration by adding a drive signal into the existing Z-feedback loop. The drive is digitally calculated from accelerometer-based vibration measurements. By transferring the vibration cancellation effort to this drive signal, vibration-created noise is significantly reduced. This inexpensive and easy solution requires no major instrumental modifications and is ideal for those looking to place their microscopes in noisier environments, coupled, for example, to active refrigeration systems (e.g., pulse tube cryocoolers) or other high-vibration instruments.

Development of a near-5-Kelvin, cryogen-free, pulse-tube refrigerator-based scanning probe microscope

“…Such integration would not only eliminate the dependency on scarce helium, but it would also enable experiments to be carried out uninterrupted without the need for cryogen refills. To this end, several SPM systems that have integrated cryogen-free refrigerators using elaborate mechanical vibration isolations have been reported [7][8][9][10][11][12] and made commercially available [13,14]. However, realizing an instrument with both a base temperature close to 4.2 K, and high-resolution measurement capabilities similar to liquid-helium-based SPM systems has remained elusive.…”