An low-cost spectrum analyzer for trouble shooting noise sources in scanning probe microscopy

TL;DR

This paper introduces a low-cost, smartphone-based spectrum analyzer for troubleshooting noise in scanning probe microscopes, enabling easy identification of interference sources without expensive equipment.

Contribution

The paper presents a novel, affordable method using a smartphone app and acoustic signals to analyze noise in scanning probe microscopes, replacing costly commercial spectrum analyzers.

Findings

Effective noise frequency identification in microscopes

Cost reduction compared to commercial analyzers

Simple setup using existing microscope signals

Abstract

Scanning probe microscopes are notoriously sensitive to many types of external and internal interference including electrical, mechanical and acoustic noise. Sometimes noise can even be misinterpreted as real features in the images. Therefore, quantification of the frequency and magnitude of any noise is key to discovering the source and eliminating it from the system. While commercial spectrum analyzers are perfect for this task, they are rather expensive and not always available. We present a simple, cost effective solution in the form of an audio output from the instrument coupled to a smart phone spectrum analyzer application. Specifically, the scanning probe signal, e.g. the tunneling current of a scanning tunneling microscope is fed to the spectrum analyzer which Fourier transforms the time domain acoustic signal into the frequency domain. When the scanning probe is in contact with the sample, but not scanning, the output is a spectrum containing both the amplitude and frequency of any periodic noise affecting the microscope itself, enabling troubleshooting to begin.