# Reduced damage in electron microscopy by using interaction-free measurement and conditional re-illumination

## TL;DR

This paper explores how interaction-free measurement combined with conditional re-illumination can significantly reduce sample damage and improve resolution in low-dose electron microscopy, using theoretical and simulation analyses.

## Contribution

It introduces a novel approach integrating IFM with re-illumination strategies to enhance imaging quality while minimizing damage.

## Key findings

- Additional scattered electron detector reduces error by up to tenfold.
- Re-illumination scheme halves the error rate.
- Methods are feasible with current TEM technology.

## Abstract

Interaction-free measurement (IFM) has been proposed as a means of high-resolution, low-damage imaging of radiation-sensitive samples, such as biomolecules and proteins. The basic setup for IFM is a Mach-Zehnder interferometer, and recent progress in nanofabricated electron diffraction gratings has made it possible to incorporate a Mach-Zehnder interferometer in a transmission-electron microscope (TEM). Therefore, the limits of performance of IFM with such an interferometer and a shot-noise limited electron source (such as that in a TEM) are of interest. In this work, we compared the error probability and sample damage for ideal IFM and classical imaging schemes, through theoretical analysis and numerical simulation. We considered a sample that is either completely transparent or completely opaque at each pixel. In our analysis, we also evaluated the impact of an additional detector for scattered electrons. The additional detector resulted in reduction of error by up to an order of magnitude, for both IFM and classical schemes. We also investigated a sample re-illumination scheme based on updating priors after each round of illumination and found that this scheme further reduced error by a factor of two. Implementation of these methods is likely achievable with existing instrumentation and would result in improved resolution in low-dose electron microscopy.