[3dem] Event-Based Electron Counting

[Benjamin Bammes]

Dear colleagues,

After 8 long years of development, I am thrilled to introduce Apollo, a new
cryo-EM camera using a novel event-based direct detection sensor.

Until now, electron counting has been done through a brute force
software-based approach, where integrating mode frames are read from a CMOS
direct detection sensor and then processed in software using an electron
counting algorithm. This has required stringent control of the beam
intensity to ensure that each frame is sufficiently sparse to avoid
coincidence loss. As a result, the vast majority of pixels in each frame
are noise. (This is why EER format has been helpful, because most pixels
delivered by current cameras are thresholded to zero and are thus not
necessary for storage and downstream processing.)

Instead of this brute-force approach, Apollo uses a new strategy:
performing electron counting in hardware by identifying electron detection
events on the sensor, centroiding each event in FPGA hardware, and
delivering super-resolution (67 megapixel) dose fractionated frames
(already counted) to the computer to be used for motion correction and
other downstream cryo-EM image processing.

As a result, Apollo does not have the electrons per pixel per second
limitations of current detectors. Apollo has high linearity and SNR up from
0.01 all the way up to 60 electrons per pixel per frame!

This has been a really fun project to work on and I'm really excited to see
the impact this has on cryo-EM in the coming years.

To everyone in the community that has given us feedback over the years, I'd
like to offer my heartfelt gratitude. Your input has been instrumental in
guiding this development, whether you knew it or not. Thank you.

Feel free to contact me directly if you have any questions, or go to
https://urldefense.com/v3/__https://directelectron.com/apollo__;!!Mih3wA!Rn4GZBSNcaYIge5ZaA0KulYqegCG8XgEgPsVlCXkhLPtGxq1BJnIUsytT9uyj0VTig$ .

----

*Benjamin Bammes, Ph.D.*
*Director of Research & Development*bbammes at directelectron.com  |  858.384.0291
x105

*DIRECT ELECTRON, LP*
https://urldefense.com/v3/__http://www.directelectron.com__;!!Mih3wA!Rn4GZBSNcaYIge5ZaA0KulYqegCG8XgEgPsVlCXkhLPtGxq1BJnIUsytT9uNNw-usA$ 

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