Dose (Camera Sensitivity) Calibration » History » Version 13
Anchi Cheng, 03/31/2022 12:02 PM
1 | 1 | Amber Herold | h1. Dose (Camera Sensitivity) Calibration |
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3 | 13 | Anchi Cheng | Dose Calibration is a calibration of digital camera sensitivity. This calibration is required only once at each high tension per instrument. |
4 | 1 | Amber Herold | |
5 | 13 | Anchi Cheng | Camera sensitivity is counts on camera per electron input. |
6 | 4 | Amber Herold | |
7 | 13 | Anchi Cheng | You can either use Faraday cup or screen current to measure electron input and camera to get average counts on the camera with the same beam or enter the pre-determined camera sensitivity value provided by camera supplier under similar condition you use for data collection. |
8 | 1 | Amber Herold | |
9 | 13 | Anchi Cheng | h2. Enter pre-determined camera sensitivity value |
10 | 1 | Amber Herold | |
11 | 13 | Anchi Cheng | * Instruction for [[K2_camera_sensitivity|Gatan K2 Summit camera]] |
12 | * For K3, follows K2 super-resolution instruction. |
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13 | 1 | Amber Herold | |
14 | 13 | Anchi Cheng | # Leginon/Dose/Calibrate/Camera Sensitivity> Enter Sensitivity values in counts per electron. |
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16 | # Leginon/Dose/Calibrate/Camera Sensitivity> Click on Save. |
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17 | 1 | Amber Herold | |
18 | 13 | Anchi Cheng | !predetermined-dose.png! |
19 | 1 | Amber Herold | |
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21 | 13 | Anchi Cheng | [[Faraday Cup Measurment Notes]] |
22 | 1 | Amber Herold | |
23 | 13 | Anchi Cheng | h2. Determine the screen current/beam current scale factor |
24 | 1 | Amber Herold | |
25 | 13 | Anchi Cheng | The following uses a Faraday cup |
26 | 4 | Amber Herold | # Scope> Move the stage to an empty area or a broken hole. |
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28 | # Scope> Adjust the beam so that it passes through the measuring area of the Faraday cup. |
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29 | 1 | Amber Herold | |
30 | 4 | Amber Herold | # Scope> Choose a magnification so that the same beam will pass within but almost to the main screen, too. |
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32 | # Leginon/Dose/Dose Calibrator> Beam Diameter = 0.16 m for Tecnai main screen. |
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34 | # Leginon/Dose/Dose Calibrator> Enter Screen Current to Beam Current Scale Factor as 1 as a starting point. |
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36 | # scope> Optionally lower the screen. Dose Calibrator will automatically do this if the user forgets. |
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38 | 1 | Amber Herold | # Leginon/Dose/Dose Calibrator> Click Measure Dose Rate. The Dose Rate, Beam Current, and Screen Magnification will appear in the corresponding fields after they have been calculated. |
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40 | 13 | Anchi Cheng | # Leginon/Dose/Dose Calibrator> Adjust the Screen Current to Beam Current Scale Factor so that the displayed beam current is equal to that of the Faraday cup measurement. NRAMM Tecnai's value is 0.88. We don't have values for other microscopes since we no longer own a Faradat cup for such calibration. |
41 | 1 | Amber Herold | |
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43 | h2. Calibrate the camera sensitivity |
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44 | 3 | Amber Herold | |
45 | 4 | Amber Herold | # Scope> Move the stage to an empty area or a broken hole. |
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47 | # Scope> Expand the beam so that it covers the main screen and illuminate it uniformly. |
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49 | # Leginon/Dose/Settings> Configure camera with override preset activated. |
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51 | # Leginon/Dose/Dose Calibrator> |
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53 | 1 | Amber Herold | ** Beam Diameter = 0.16 m for the Tecnai's main viewing screen. |
54 | 4 | Amber Herold | |
55 | 3 | Amber Herold | ** Screen Current to Beam Current Scale Factor = (as determined above or 1 to assume good calibration by the microscope manufacturer) |
56 | 1 | Amber Herold | |
57 | # scope> Optionally lower the screen. Dose Calibrator will automatically do this if the user forgets. |
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58 | |
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59 | # Leginon/Dose/Dose Calibrator> Click Measure Dose Rate. The Dose Rate, Beam Current, and Screen Magnification will appear in the corresponding fields after they have been calculated. |
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60 | 11 | Anchi Cheng | |
61 | # Leginon/Dose/Dose Calibrator> Without changing the beam intensity, click on "Calibrate". An image is acquired by Leginon. |
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62 | 12 | Anchi Cheng | |
63 | 3 | Amber Herold | *Leginon will automatically lift the main viewing screen on the microscope. Some users report that the function does not work on their microscopes. Do it manually if the automatic function does not work. |
64 | 6 | Jim Pulokas | |
65 | 4 | Amber Herold | # The calculated camera sensitivity (counts / electron) will display once the calculation is completed. |
66 | 6 | Jim Pulokas | |
67 | 2 | Amber Herold | |
68 | 5 | Jim Pulokas | |
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70 | 4 | Amber Herold | *Dose Calibration Need for the Example MSI:* |
71 | 2 | Amber Herold | |
72 | |_.Preset|_.magnification| |
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73 | |*|any| |
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78 | 1 | Amber Herold | ______ |
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80 | [[Autofocus Calibration with Beam Tilt Node|< Autofocus Calibration with Beam Tilt Node]] |
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82 | ______ |