eli5 What is a Ronchigram

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Saw it on twitter and tried googling it. Can’t figure it out. What is a Ronchigram?

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Anonymous 0 Comments

It’s a way of calibrating the focal length of an electron microscope and checking if its lens is free from flaws.

Basically you project the electron beam at a thin film made of amorphous materials with a screen behind it.

The projected image becomes a weird blur/blob, and depending on what the blob looks like you have an idea of how you’re going to correct the electron microscope until you get a blob that looks vaguely like a six-pointed star. The electron microscope is then correctly calibrated and you can use it to view atom-sized objects.