# Beam divergence

Submitted by kodera on Tue, 2017-04-18 13:14

Forums:

It is possible to define beam divergence in BornAgain.

It is very attractive feature!

I found some examples of BornAgain usage, but I could not find the calculation algorithm on the beam divergence.

Would someone kindly tell me the algorithm used in BornAgain?

herck

Tue, 2017-04-18 13:41

Permalink

## Dear Mr. Kodera,

Dear Mr. Kodera,

Thanks for the positive feedback! As for the algorithm, each distribution (angle/wavelength) is sampled and for each sample the simulation image is calculated. The individual scattering intensities are then added with a weight corresponding to the probability measure of the sample. The addition is thus an incoherent sum of intensities.

To understand how these distributions are defined and sampled in BornAgain, the easiest way is to look at the instrument tab of the BornAgain application. Next to wavelength (or inclination/azimuthal angle) you will see a small looking glass. When you click this, you can adjust the different parameters defining the distribution and you immediately get a graphical representation of this. In case of the wavelength, there is an additional constraint (it must be positive) which has an impact on how the distribution will be sampled.

If you have further questions, please let me know.

Kind regards,

Walter

kodera

Tue, 2017-04-18 14:24

Permalink

## Thank you for your

Thank you for your instructions!