Add handling of diffractive optics

[klaff]

For example, surface 1 of this part https://www.edmundoptics.com/p/12mm-dia-x-9mm-fl-vis-coated-hybrid-asphere/20519/ combines an aspherical profile with a diffractive step pattern.

[friggog]

I wrote some (very) basic support for some diffractive elements, specifically planar diffraction gratings and HOEs. It would be amazing to extend this to components link the example you gave - the current code should provide a good basis for doing so.

I don’t think this is a high priority for any of the current team but if you want to have a go then that would be fantastic!

[klaff]

I am tempted but I think I will throw a couple of other problems at OpticSim (which I believe it can already handle) and get to learn the package first.

Is the code you mentioned in the package already? And/or did you have a reference (paper or book) for the approach you took? Thank you!

[friggog]

It’s all in Grating.jl - the equation numbers from kogelnik are commented, although I think I left out a reference to the actual paper - it’s coupled wave theory for thick hologram grating