+1I’d like to show scattering in a sequential model layout.
It seems that sequential surface scatter is non recognized.
I’ve done some experimenting with a non-sequential component with source and scattering surface, but I don’t see any changes with or without the “Scatter NSC Rays” checked in the layout. Can someone point me in the right direction?
Thank you,
John
Best answer by Mark.Nicholson
Hi John,
Back in the day, we decided that scattering in purely sequential systems would be supported, but not drawn on layouts because only very small angle scattering works in sequential mode.
If you want things like RMS spot size, MTF etc to work, the scattering MUST be small: if it’s not, use non-sequential where scattering support is unrestricted.
We didn’t draw the scattering in sequential mode because, if the scatter is big enough to be seen on the layout then it shouldn’t be used. It’s best reserved for things like Geometric Image Analysis.
Also, in hybrid NS mode, rays can scatter but not split. Because the ray ultimately makes its way back into the sequential ray-tracer, we have to conserve the number of rays traced. Imagine using an REAY operand with a ray that splits into 5 separate rays, with none of them being the specular ray. Which one would REAY pick up?
Bottom line: use scattering in sequential mode only if it is low angle, and you are using features like GIA, spot size and Geometric MTF. For everything else, use NS.
Note these decisions were made ~15 years ago and can be changed if there’s a compelling reason, but that’s why the code is the way it is right now.
+2Hi
I believe points 4 and 5 of the NSC ray tracing in mixed mode (with entry and exit ports) section might help:
4) OpticStudio traces a ray sequentially to the entry port, then non-sequentially within the non-sequential group, until the ray strikes the exit port.
5) Rays entering the non-sequential group through the entry port cannot split. Note that ray splitting is required to trace the ordinary and extraordinary rays for birefringence in non-sequential mode. If a birefringent material is defined in non-sequential group, rays will always follow the ordinary path, regardless of the mode setting on the birefringent object.
So it might just not be possible at all :(
Take care,
David
+3Hi John,
Back in the day, we decided that scattering in purely sequential systems would be supported, but not drawn on layouts because only very small angle scattering works in sequential mode.
If you want things like RMS spot size, MTF etc to work, the scattering MUST be small: if it’s not, use non-sequential where scattering support is unrestricted.
We didn’t draw the scattering in sequential mode because, if the scatter is big enough to be seen on the layout then it shouldn’t be used. It’s best reserved for things like Geometric Image Analysis.
Also, in hybrid NS mode, rays can scatter but not split. Because the ray ultimately makes its way back into the sequential ray-tracer, we have to conserve the number of rays traced. Imagine using an REAY operand with a ray that splits into 5 separate rays, with none of them being the specular ray. Which one would REAY pick up?
Bottom line: use scattering in sequential mode only if it is low angle, and you are using features like GIA, spot size and Geometric MTF. For everything else, use NS.
Note these decisions were made ~15 years ago and can be changed if there’s a compelling reason, but that’s why the code is the way it is right now.
+1Hello
All your points make sense. Thanks.
My desire to show scattering on the layout is to have a representative layout image that can pair with the geometric analysis with scattering on. This at the qualitative level for a presentation.
I was working with low angle scatter to ‘engineer’ a psf for extended depth of field, related to post:
Thank you,
John
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