4D-STEM and Ptychography Workshop

 

4D-STEM collects diffraction patterns at a series of electron beam positions, creating 4-dimensional datasets that can be processed post-collection or in a near-live condition to reveal insights into the sample material. This workshop will guide participants through the background, collection and data processing aspects of 4D-STEM, through demonstrations and hands-on walk throughs of Python based examples.

Attendees bringing their own computer will be instructed on installing and running Python modules such as Hyperspy and Pixstem for processing 4D-STEM data. Data acquisition is usually performed with vendor software, such as the Hitachi Azorus system, which will be used in this workshop for illustrative purposes. Ptychography, which can yield quantitative phase and amplitude information on the electron transmission from processing specific 4D-STEM data collected under appropriate conditions on suitable samples, will also be discussed and demonstrated, within the schedule below:

1. Introductions and Python Environment Installation [15 min]
   • Introduction to 4D STEM [30 min]
   • Development of detectors enabling 4D-STEM
   • What can be done with 4D-STEM data?
     • Virtual detectors
     • Model fitting
     • Mapping
     • Phase retrieval
2. Typical 4D Data Acquisition workflow [15 min]
   • Use of high-speed detectors with random-access 4D scans
   • Illustration of workflow for acquiring overview STEM scans and diffraction data
3. Break for coffee and discussion [20 min]
4. Tutorial on manipulating acquired data set with open-source software (eg, Hyperspy and PixSTEM) [40 mins]
   • Overview of open-source code considerations.
   • Work through tools to create a variety of virtual detector images
5. Ptychography [20 min]
   • Introduction to ptychography as a quantitative phase imaging technique.
   • Demonstrations of reconstruction process
6. Questions and Discussion [10 min]

To register and receive introductory setup instructions if you intend to join the demonstrations using your own computer, please e-mail ablackbu@uvic.ca.