Simple geometrical source beam propagation monitoring about xrt

[kklmn]

Hi,
You define x' and z' distributions as "none":

distxprime="none",
distzprime="none", 

The docs define the valid values as ‘normal’, ‘flat’, ‘annulus’ or None. Note, 'none' is not among them but it does nothing as well. So if you want a normal or flat distribution, you have to define it.

[emasimak]

HI!
Thank you for your quick reply!
... and thank you for pointing out this silly mistake! I would not have noticed it.
If I were to use None for the distributions of dxprime and dzprime however, wouldn't that mean that the divergence should remain constant through the beam propagation? My understanding is that dx,dz are the beam sizes and dxprime, dzprime the angular divergence in each of the axes. So a constant angular divergence of dxprime would affect the FWHM of the beam in x as: (FW' - FW)/(distance) = dxprime. I tried to use also "flat" but I had the same results in terms of beam size.
I am misunderstanding something in the definition. If you can offer any advice it would be much appreciated.

[kklmn]

If I were to use None for the distributions of dxprime and dzprime however, wouldn't that mean that the divergence should remain constant through the beam propagation?

Not just constant but zero. The size of None distribution is irrelevant. I don't see why a size parameter should define the central value. For the central x' and z' we have yaw and pitch.

I tried to use also "flat" but I had the same results in terms of beam size.

Then something is wrong in your script again.

[kklmn]

If scripting is a problem, there are many ready examples to look at in 'examples' and 'tests'.
In particular, you may examine this one: tests/raycing/test_param_mirror.py.

[emasimak]

Hi!
Your point on the central values being unaffected is perfectly clear. I was expecting that the FWHM values would change based on the angular distributions.
Thank you for the script! It is indeed very helpful to see an example.
I think my issue was in the plot definition (more specifically the fact that I had limits). It seems that I can now see the expected (based on the distxprime and dxprime that I define) angular distributions in the plots.
Thank you for the help!

[emasimak]

Hi!
I thought I had understood how the definition of dxprime, dzprime worked but apparently not.

I am attaching a sketch to explain what I want to define in the code.

On the left you see the beam that is defined through a GeometricSource when:
distx="normal", dx=Sx/2.355, disty=None, dy=0., distz="normal", dz=Sy/2.355

One the right you see the divergence I want to include in the beam. I want to accomplish a beam size of:
Sx' = Sx + (θ * dist).
I was expecting that if I define distxprime='flat', dxprime=1e-3, distzprime='flat', dzprime=1e-3
that θx (or 2θx) [rad] would be equal to dxprime (similarly for the zaxis) and that if I place a screen in 1m distance I would see an increase of Sx equal to 1mm. Instead I get the beam sizes shown in the picture below.

It is not clear to me how I should define dxprime/dzprime to accomplish the beam divergence that I need.
Thank you in advance for your time!
/Myrto

// Used code:
geometricSource_wOneCrystal-demo_py.txt

[kklmn]

Hi!

distx and distxprime are independent distributions. In other words, in your picture of the red source spot, each point has a random angular distribution distxprime, not that the top part will have positive inclinations.

What you describe as your expectation is a point source with a truncated tip, no idea why you want it truncated.

If you need a defined fan of rays then just define it as a point source. Then x and x' will be explicitly dependent at every distance D from the source as x = D x'.

[emasimak]

Hi!
Thank you for quick and helpful clarification! I will keep it in mind.
I assume that as point source you refer to the MeshSource, right?

Thank you for your time!
Myrto

[kklmn]

A point source is the same GeometricSource with distx, disty and distz as None.

[emasimak]

Thank you!