A Scanning 2-Grating Free Electron Mach-Zehnder Interferometer

TL;DR

This paper presents a novel free electron Mach-Zehnder interferometer built within a transmission electron microscope, enabling precise phase measurements and nanoscale imaging using electron interference.

Contribution

The work introduces a 2-grating electron interferometer with real-time phase measurement and large path separation capabilities, advancing electron phase imaging techniques.

Findings

Successfully demonstrated phase shifts measurement due to electrostatic potentials.

Achieved quantitative nanoscale phase imaging of nanoparticles.

Enabled real-time phase information in electron interferometry.

Abstract

We demonstrate a 2-grating free electron Mach-Zehnder interferometer constructed in a transmission electron microscope. A symmetric binary phase grating and condenser lens system forms two spatially separated, focused probes at the sample which can be scanned while maintaining alignment. The two paths interfere at a second grating, creating in constructive or destructive interference in output beams. This interferometer has many notable features: positionable probe beams, large path separations relative to beam width, continuously tunable relative phase between paths, and real-time phase information. Here we use the electron interferometer to measure the relative phase shifts imparted to the electron probes by electrostatic potentials as well as a demonstration of quantitative nanoscale phase imaging of a polystyrene latex nanoparticle.