Use the spec divergence half-angle

[ederag]

BeamletOptics calculate the half-angle divergence (fine)

BeamletOptics.jl/src/Utils/OpticUtils.jl

Line 63 in 99636a3

divergence_angle(λ, w0, M2) = M2 * λ / (π * w0)

but thorlabs specifies the full-angle:

The HRS015B beam divergence of 1.4 ± 0.2 mrad
is based on the 1/e² falloff, and is a full-angle measurement

So the actual M2 should be 1.13 (that looks plausible for an He-Ne) rather than 2.26.

The last change displayed in the diff is actually only about \ No newline at end of file
(the line itself has not changed at all, only a newline character has been added automatically by github).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.46%. Comparing base (99636a3) to head (a3bf1c2).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #26   +/-   ##
=======================================
  Coverage   71.46%   71.46%           
=======================================
  Files          57       57           
  Lines        2793     2793           
=======================================
  Hits         1996     1996           
  Misses        797      797           

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[StackEnjoyer]

Thanks for pointing this out! I have added additional fixes in order to update all plots and results here: https://github.com/JuliaPhysics/BeamletOptics.jl/tree/Fix-HeNe-divergence-angle

This concerns the:

• detector size, since the spots and fringes are now smaller
• intro fig, which now also displays the beam

Please consider adding these changes to your fork/PR and I will add my review. Alternatively, I can merge the linked branch directly, with proper attribution to you of course.