Electron Microscopy Drift Compensation for Radiation-Sensitive Specimens
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Solution Overview
Problem
High-resolution electron microscopy is hindered by image drift, which causes blurring, and radiation-sensitive specimens are irreversibly damaged by the high radiation dose required for accurate drift estimation, rendering subsequent images unusable.
Innovation Solution
An electron-microscopy system with a fast controllable beam deflector and drift-estimation algorithm that locks onto drift-induced motion without exposing the specimen to a high radiation dose, using a charged particle beam system with active optical control and electro-mechanical compensation to maintain image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high radiation dose is applied to obtain an accurate initial drift estimate, then drift estimation accuracy is improved, but radiation damage to the specimen worsens
Solution Approach 1:
The patent divides the sample into different portions: a first portion used for drift estimation and a second portion (POI) containing the radiation-sensitive specimen. The beam alternates between these portions, allowing drift measurement without exposing the sensitive specimen to high radiation doses.
Solution Approach 2:
The patent introduces an intermediary region (first portion) that serves as a proxy for drift measurement. This intermediary area absorbs the radiation dose required for accurate drift estimation, protecting the actual specimen of interest from radiation damage while still providing the necessary drift data.
2Measurement precision
If the electron beam is continuously applied to the specimen for drift estimation, then drift measurement accuracy is improved, but specimen integrity worsens
Solution Approach 1:
The patent implements periodic beam switching between the first portion (for drift estimation) and the second portion (POI containing the specimen). This periodic action allows drift measurement to occur intermittently without continuous exposure of the sensitive specimen, maintaining both measurement accuracy and specimen integrity.
3Object-affected harmful factors
If beam deflection is used to move the electron beam away from the specimen during drift estimation, then radiation exposure of the specimen is reduced, but drift estimation accuracy may worsen
Solution Approach 1:
The patent uses beam deflection to redirect the electron beam to an intermediary first portion of the sample that is spatially separated from the POI. This deflected beam position serves as a mediator for drift measurement, providing accurate drift data while the specimen remains unexposed to the beam during these measurement phases.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-resolution imaging of radiation-sensitive specimens without significant radiation damage by accurately compensating for drift through controlled beam deflection and stage actuation, preserving image quality.
Implementation Method 1
a drift-estimation algorithm that locks on the drift-induced motion when the beam deflector places the electron beam into a first position on the sample
Implementation Method 2
A controlled actuation system, often referred to as 'stage,' can be used to move the sample holder during the image-acquisition process to counteract the drift-induced motion
Data Source
AI summary
In one example, a method performed via a computing device for providing support to a charged particle beam system includes computing a drift estimate based at least in part on a first set of image frames acquired with a charged particle beam column and a detector from a first portion of a sample. The method also includes configuring the charged particle beam column and the detector to acquire a second set of image frames from a second portion of the sample. The method further includes performing drift compensation during acquisition of the second set of image frames based at least in part on the drift estimate.