Arbitrary dose patterns
This data shows the exquisite control achieved by Programmable STEM with EDM Synchrony.
(Left) User-defined test pattern with a variety of high-resolution features. The gray level in each pixel tells Synchrony how long to expose. This test pattern was used during a scan of Au nanoparticles using a JEOL GRAND ARM™2 TEM, resulting in a modulated bright-field image (Right).
The nanoparticles are clearly visible, as are the logo graphics, the test patterns, and the photograph of the TEM from the modulation image.
Images courtesy of The Rosalind Franklin Institute, UK.
Dose Painting
Annular Dark Field measurement* of grating replica with latex spheres, with exposure mask applied.
"The Great Wave off Kanagawa," exposure mask.
Dose Painting creates precise exposure patterns by synchronizing an electrostatic blanker to a STEM scan. Here, we demonstrate this capability by exposing Katsushika Hokusai’s ukiyo-e, "The Great Wave off Kanagawa," onto a grating replica sample using a 200 keV electron beam in a JEM-ARM200F. As seen in the comparison between the original image and the Annular Dark Field image written by Dose Painting, the grayscale variations and fine structural details of each pixel are faithfully reproduced.
The pattern was applied in a TEM using the Dose Painter software, which is part of the Electrostatic Dose Modulator (EDM) Synchrony system from IDES, Inc. First, a color image of "The Great Wave off Kanagawa" was converted to a 1,024 × 1,024-pixel grayscale exposure mask in TIFF format using a free and open-source raster graphics editor GIMP. Next, Dose Painter synthesized the mask into a pulse sequence. EDM Synchrony directed the electrostatic blanker to control the exposure time at each pixel of a STEM scan. The dwell time was 38.5 μs per pixel and the exposure area on the surface of the grating replica was approximately 6.6 μm × 6.6 μm.
This process can be executed on any TEM equipped with EDM Synchrony by IDES. This measurement was taken using Digital Micrograph 3 and DigiScan 3 by Gatan. JEOL TEM Center and FEMTUS™ are also supported.
*Data courtesy of Lluis Lopez Conesa, PhD, the Centres Cientifics i Tecnologics de la Universitat de Barcelona (CCiTUB).
True Area STEM Imaging with reduced beam damage
True Area STEM (TAS) imaging technology with Electrostatic Dose Modulator (EDM) Synchrony*1 can reduce specimen damage during STEM imaging. EDM Synchrony is integrated with the JEOL STEM system to make a complete flyback blanking solution. The scanning system has an unusable pre-scanning area where the magnetic coil's response is nonlinear in time and data is not acquired. Unnecessary electron radiation damage can occur in this pre-scanning area.
Flip-book animations (YouTube)
The data
*2 above are arrays of STEM images obtained using a sample, talc in riebeckite (mineral)
*3, scanned 50 times. The top row shows images acquired without TAS, while the bottom row shows images acquired in TAS mode. In the top row, significant electron beam damage is observed at the left edge of the field of view due to damage originating from the electron beam in the pre-scanning area (just outside the field of view). In contrast, in the bottom row with TAS mode, no damage caused by the fly-back irradiation is observed.
1 True Area Scan mode is available with EDM Synchrony. In case that the TEM control system is FEMTUS
TM-MDP, both EDM Basic and EDM Synchrony can provide TAS mode.
2 Measurement conditions: Instrument JEM-ARM300F2, accelerating voltage 300 kV, electron beam current 5 pico-amperes, dwell time 16 microseconds, number of pixels 512 × 512.
3 The boundary between phyllosilicate (talc) and amphibole (riebeckite) in crocidolite asbestos.
STEM Damage Reduction using EDM Synchrony
The Dose Painting feature of electrostatic dose modulator (EDM) Synchrony allows the electron dose to be adjusted for each pixel. Here we show an example of how Synchrony can reduce electron beam damage during atomic resolution STEM, by controlling with subatomic precision which regions are irradiated. In an atomic-resolution scan of SrTiO3, we only illuminate the regions near the high-contrast Sr atomic columns, allowing us to track the crystal lattice while avoiding exposure of vacuum areas and other atomic columns.
This greatly reduces the damage per scan, allowing quantitative analysis over extended periods of time. Below we show a negligible loss of X-ray intensity even after 10 minutes of continuous scanning. For advanced users comfortable with coding, Synchrony’s automation interface lets you customize this approach for your sample, defining any grayscale exposure mask you like based on an atomic resolution preliminary scan. This lets you specifically place dose to reduce damage and enhance the return of the information you care about.
Mask pattern set by Dose Painting
Images A, B, and C are annular dark field (ADF) images taken after 10 minutes of electron beam irradiation. The irradiation conditions were as follows: A was captured in the standard STEM mode, B in the True Area Scan mode (i.e. with the beam blanked during flyback), and C in the True Area Scan mode combined with a mask using Dose Painting. Graphs D, E, and F show the change in X-ray intensity of strontium with increasing dose over 10 minutes of irradiation. A corresponds to D, B to E, and C to F. Both the ADF images and the attenuation of X-ray intensity demonstrate that the combination of True Area Scan and Dose Painting greatly reduces damage to the sample.