the DQE of K2 summit which installed last week.

Submitted by Kunpeng on Tue, 2015-07-28 10:35

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FindDQE

Fresh K2 summit be installed on our Titan last week. the DQE curve and the images of beam stop were post here, and the silhouettes were imaged at High Voltage: 300kV, dose: 50e/pixel, pixel size: 1.31A/pixel. I just used e2proc2d.py to average the DM4 stack images to a MRC file.

I have two questions here,

1) The NPS still too low, and the DQE curve of counted mode much lower than the number given by factory. and There are many bright pixels within the beam stop region (see attached images) which should be completely black. I can't find the reason, should I use the unblur to alignment the frames in the moive then summed them up?

2) There is one error message when I deal with the super-resolution mode image with findDQE.

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Determining image threshold

Threshold = 4.47827615E-02
N, DMEAN, DRMS inside pointer = 26963543 1.52597297E-02 1.55108580E-02
N, DMEAN, DRMS outside pointer = 28092857 7.43057951E-02 2.38520112E-02
Gain conversion factor (counts/e) = 9.28822439E-04

Thresholding image
Removing single pixel outliers

Number of pixel outliers = 13576109
Try a higher dose to reduce outliers to zero

Pointer distance from edge: 6 7415 8 7387
ERROR: Pointer less than 405 from edge
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dqe-5e-10s-29: 5e: 5e/pixel/s, 10s: exposure time, 29: total dose 29e/A^2
dqe-1e-7s-sr, 1e: 1e/pixel/s, 7s: exposure time, sr: super resolution mode

Alexis Tue, 2015-07-28 10:48

Your images do not look like they have the number of electrons you report. Are you sure you converted all the frames in the stacks and averaged them together? Could it be you only converted the first frame, for example? Perhaps something went wrong in the file conversion?

Kunpeng Wed, 2015-07-29 09:29

I confirmed that e2porc2d.py converted all the frames and averaged. but I don't know how difference between averaged them and summed them up. I'll try the unblur and summovie later.