TEM 專用數位影像系統

TEM 專用數位影像系統


In a revolutionary new approach to recording TEM images, the DDD sensor images high-energy electrons directly. By avoiding the electron-to-light conversion process of a scintillator, the DDD achieves unprecedented sensitivity and resolution. Targeted especially for low-dose biological imaging, the DDD represents an important innovation that will propel the next generation of discovery.

The DE-12 Camera System is based on a 12 Mpixel DDD sensor featuring a 4K by 3K array of 6 micron pixels.

The NEW DE-20 Camera System is based on a 20 Mpixel DDD sensor featuring a 5K by 4K array of 6 micron pixels.

DE-12/20 DDD® Camera


Edge Profile Comparison (300kV)

DQE comparison

The DE-20 provides the largest field-of-view of any direct detection TEM camera for single-particle analysis (SPA), even assuming the best case performance for competing cameras.

The DE-20 provides the largest field-of-view of any direct detection TEM camera for cryo-tomography, even assuming the best case performance for competing cameras.

Application:

10 k x 7 k mosaic image from 9 individual Automated Multi-Scale Imaging of ice-embedded images, 1 sec per image, mouse cerebellum, GroEL and TMV acquired at 120 keV FEI Tecnai Courtesy Tom Deerinck, UCSD Automated Multi-Scale Imaging of ice-embedded images, 1 sec per image, mouse cerebellum, GroEL and TMV acquired at 120 keV FEI Tecnai Courtesy Tom Deerinck, UCSD microscope using Leginon. Image mag at 290X, 2,700X, and 21,000X. Dose in the final image is 11 e-/A2. Image courtesy of AMI, TSRI

High-throughput Direct Detection

DE-20 provides the largest pixel area of any direct detection TEM camera. The field-of-view of the DE-20 (5120×3840) is17% larger than a 4096×4096 integrating-mode camera and 38% larger than a 3838×3710 counting-mode camera.

Additionally, because the DE-20 (operating in integrating mode) is not constrained by the sparsity condition of electron counting, the exposure time on the DE-20 can be maintained at similar times as used with CCD cameras or film.

This combination of large field-of-view and short exposure time means that the DE-20 is the highest-throughput direct detection TEM camera available.

The DE-20 provides the largest field-of-view of any direct detection TEM camera for single-particle analysis (SPA).

Assumes 3 e-/pixel/s in order to minimize coincident electrons and optimize performance. Users may use different conditions by adjusting the balance between field-of-view, exposure time, and performance (loss of counts due to coincident electrons).

The vast majority of cryo-EM single particle analysis (SPA) experiments have a target resolution of not better than 6 Å. The figure above shows the field-of-view provided by various cameras for a single-particle experiment targeting 7.5 Å resolution with 30 e-/Å2 total exposure.

For such an experiment, the DE-12 (4096×3072) and DE-20 (5120×3840) would use ~20,000× detector magnification for 3 Å/pixel (Bammes et al., J Struct Biol 2012, doi: 10.1016/j.jsb.2012.01.008) to maximize field-of-view. This image could be acquired, for example, within 1 second.

A 4096×4096 integrating-mode direct detection camera would likely require similar Å/pixel sampling (although the magnification may be different depending on the camera’s pixel size). Compared to such a camera, the DE-20 would provide 17% larger field-of-view.

Determining the field-of-view of a 3838×3710 counting-mode direct detection camera is not as straight-forward. Electron counting requires a low exposure rate (“sparsity condition”) to reduce the occurrence of coincident electrons, which may significantly diminish the performance of the camera. For a camera operating at 400 frames per second (fps), performance degradation due to coincident electrons is minimal at <3 e-/pixel/s (Li et al., Nat Meth 2013, doi:10.1038/nmeth.2472). Due to this sparsity condition, a counting camera requires a trade-off between field-of-view, exposure time, and performance. For optimal performance (3 e-/pixel/s), one could choose 1.25 Å/pixel sampling (note that lower magnification may require an impractically long exposure time). At this condition, the DE-20 would provide 695% larger field-of-view. Furthermore, if the camera were operating at 400 frames-per-second, such an image would require 15.6 seconds exposure time in order to accumulate the necessary 30 e-/Å2 total exposure. Of course, the exposure time for a counting camera could be reduced by sacrificing overall performance and using a higher exposure rate (e.g., 10 e-/pixel/s resulting in a 4.7 s exposure).

The DE-20 provides the largest field-of-view of any direct detection TEM camera for tomography.

Assumes 3 e-/pixel/s in order to minimize coincident electrons and optimize performance. Users may use different conditions by adjusting the balance between field-of-view, exposure time, and performance (loss of counts due to coincident electrons).

The figure above shows the field-of-view provided by various cameras for a typical cryo-tomography experiment targeting better than 20 Å resolution with 1.5 e-/Å2 exposure per tilt image.

For such an experiment, the DE-12 (4096×3072) and DE-20 (5120×3840) would use ~8,000× detector magnification for 7 Å/pixel to maximize field-of-view. This image could be acquired, for example, within 0.5 second.

A 4096×4096 integrating-mode direct detection camera would likely require similar Å/pixel sampling (although the magnification may be different depending on the camera’s pixel size). Compared to such a camera, the DE-20 would provide 17% larger field-of-view.

Similar to the single particle experiment explained above, determining the field-of-view of a 3838×3710 counting-mode direct detection camera must account for the sparsity condition required for efficient electron counting. For optimal performance (3 e-/pixel/s), one could choose 5 Å/pixel sampling (note that lower magnification may require an impractically long exposure time). At this condition, the DE-20 would provide 171% larger field-of-view. Furthermore, if the camera were operating at 400 frames-per-second, such an image would require 12.5 seconds exposure time in order to accumulate the necessary 1.5 e-/Å2 exposure per tilt. Of course, the exposure time for a counting camera could be reduced by sacrificing overall performance and using a higher exposure rate (e.g., 10 e-/pixel/s resulting in a 3.8 s exposure).

Learn more about our revolutionary cameras for electron microscopy at “ directelectron.com”