JEOL Ltd. (President Gon-emon Kurihara) announces the release of a new STEM (scanning transmission electron microscopy) detector “4DCanvas” (pixelated STEM detector), to be released in July 2017.

Product development background

The recent transmission electron microscope (TEM) enables a sub-Å electron probe to be formed with a spherical aberration corrector (Cs corrector). Owing to Cs correction, atomic-resolution STEM has reached a general use along with various STEM detectors for diversified observation purposes. In the STEM detector, the extremely small probe scans over the specimen and maps on each pixel signals of transmitted and diffracted electrons.
An innovative new detector “4DCanvas” records position and intensity of all the transmitted, diffracted and scattered electrons as a 2-dimensional (2D) pattern for every pixel of STEM image. The sensor of this pixelated detector is a direct electron detection CCD with 264 × 264 pixels. In other words, the detector acts as a highly sensitive multi-channel STEM detector with channels of 264 × 264. The recorded data with this detector is 4-dimensional (4D) with axes of x & y of STEM pixel positions and u & v of detector pixel positions. “4DCanvas” is named after the dimensions of the acquired data with the detector. There have been several applications using the “4DCanvas”.

• Visualization of magnetic/electric field vectors by recording a shift of a transmitted beam or the center of mass for each diffraction pattern.
• Since the user can create and assign an arbitrary-shaped detector on the detector plane, a STEM image is detected by the arbitrary-shaped detector. This unique capability enables high contrast imaging (e.g. differential phase contrast image).
• By performing ptychography, a wave field of a transmitted electron beam can be reconstructed. Thus, we can observe a phase image of a sample with high efficiency. Since the detector can compensate the phase on the diffraction plane, it enables us to correct aberrations by post-processing. A series of optically sectioned Z-sliced images can be obtained (defocus is one of aberrations). The aberration corrected image is also obtained through the post processing process.

The potential applications of “4DCanvas” are expected to be increasing. This revolutionized “4DCanvas” will offer a platform to users of electron microscopes as if they freely draw a map on the canvas.

Main Features

• JEOL pixelated STEM detector
  High read-out rate of the detector enables fast acquisition of STEM images. Its signal-to-noise ratio is as high as 300:1. The quantum efficiency of this sensor is almost 100%, since the pixel size in x, y and z is large enough to detect all incoming electrons. Thus, the pixelated detector is very suitable for low-dose imaging. Furthermore, the detector functions as a high-speed and highly-sensitive direct electron detection camera for TEM imaging.
• Optimum mounting position of the detector
  “4DCanvas” is placed beneath the viewing chamber, thus simultaneous acquisition of the data for the HAADF (high-angle annular dark-field) STEM detector is possible, resulting in the comparison of images by a “4DCanvas” and a HAADF detector.
  Since the detector is retractable, various types of cameras can be attached in the opposite face of a housing chamber. An EELS (electron energy-loss spectrometer), which is mounted at the bottom of the microscope column, is usable by the retraction.
• High-speed STEM data detection
  “4DCanvas” achieves high-speed STEM image acquisition of 1,000 fps or higher, as are shown below, because the sensor is CCD, which is capable of binning.
  1,000 fps (full-frame readout, 264 × 264 pixels)
  STEM image acquisition time for 256 × 256 pixels: 64 s
  2,000 fps (1 × 2 binning, 264 × 132 pixels)
  STEM image acquisition time for 256 × 256 pixels: 32 s
  4,000 fps (1 × 4 binning, 264 × 66 pixels)
  STEM image acquisition time for 256 × 256 pixels: 16 s
• Detection of a wide range of accelerated electrons
  “4DCanvas” can also detect a wide range of accelerated electrons, ranged from 30 kV to 300 kV. This feature enables us to optimize an accelerating voltage depending on the specimen. Thus, the detector is applicable to a specimen susceptible to electron-beam irradiation.
• Installation of the pixelated detector, “4DCanvas”
  “4DCanvas” can be installed into the JEM-ARM300F and the JEM-ARM200F.
  Notice: In the near future, installation into the JEM-F200 will be possible.
• Software
  “4DCanvas” has software that creates synthetic STEM images reconstructed from the 4D data.
  The software can map the amount and direction of beam shift for each electron probe position, resulting in a map of electric-magnetic fields vector, whose components are intensities and direction.