# Beam on BornAgain

file:///usr/share/doc/bornagain/html/ref/instr/beam/index.html Recent content in Beam on BornAgain Hugo en-us

# Footprint

file:///usr/share/doc/bornagain/html/ref/instr/beam/footprint.html Mon, 01 Jan 0001 00:00:00 +0000 file:///usr/share/doc/bornagain/html/ref/instr/beam/footprint.html <h3 id="footprint-correction">Footprint correction</h3> <p>The footprint effect originates from the angle-dependent intersection of a finite beam with a finite sample. It should be considered for all scanning simulations.</p> <div class="galleryscg "> <div class="row justify-content-center align-items-center"> <figure > <a href="file:///usr/share/doc/bornagain/html/img/draw/FootprintScheme.png"> <img src="file:///usr/share/doc/bornagain/html/img/draw/FootprintScheme.png" width="350px"> </a> <figcaption> <p></p> </figcaption> </figure> </div> </div> <p>When taking into account footprint correction, there are two possible options for the beam shape in <code>BornAgain</code>:</p> <ul> <li>Square beam &mdash; the beam has sharp edges and square cross-section, its intensity is uniformly distributed.</li> <li>Gaussian beam &mdash; the beam is infinite in space, while its intensity has Gaussian distribution along the radius of the beam.</li> </ul> <p>The footprint correction for square beam is defined by <code>FootprintSquare</code> command, which has the signature</p>

# Beam divergence

file:///usr/share/doc/bornagain/html/ref/instr/beam/divergence.html Mon, 01 Jan 0001 00:00:00 +0000 file:///usr/share/doc/bornagain/html/ref/instr/beam/divergence.html <h2 id="beam-divergence">Beam divergence</h2> <p>By default, the incident beam is perfectly monochromatic and collimated. Here we show how to set finite distributions of wavelengths and of grazing angles.</p> <ul> <li>The wavelength follows a log-normal distribution around the mean value of 0.1 nm with a scale parameter equal to $0.1$.</li> <li>Both incident angles follow a Gaussian distribution around the average values $\alpha_i = 0.2 ^{\circ}$ and $\varphi_i = 0^{\circ}$, respectively and $\sigma_{\alpha_i} = \sigma_{\varphi_i} = 0.1^{\circ}$.</li> </ul> <p>First, the <a href="file:///usr/share/doc/bornagain/html/ref/other/distributions">distributions</a> should be defined:</p>