LabAdviser/314/Microscopy 314-307/TEM/ETEM/reference-images

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(content by Jens Kling @DTU Nanolab, February 2022)

Dark and Gain reference on OneView

Every acquired image on the camera consists of:

• the acquired image (raw data)
• dark reference of the camera (noise of the chips and electronics; measure on the not-exposed camera)
• gain reference of the camera (response of the chip/fiber optics; measure without sample with beam on camera)

When the camera/electronics are switched off and on often, it might be necessary to acquire new dark and gain references. Remember: When a new dark reference is acquire, a new gain reference needs to be acquired as well. The gain reference is dependent on the high tension used, the dark reference is independent.

GMS has a procedure to acquire new reference images. Remember: When new reference images are acquired, the old ones are deleted. The whole process takes about 25min.

1. Make sure you are a Power User
2. Go to Camera and find Prepare Dark Reference The software will guide you through the process. Close the Column valve and lower the phosphorous screen (no light on the camera).
3. After the dark reference, go to Camera and find Prepare Gain Reference The software will guide you through the process. You need to find vacuum area in your sample. Spread the beam to homogeneously illuminate the camera with the indicated counts.
4. After done, start working again.