@hastea 

As far as I know you can’t directly get the PSF of a non-sequential system. Without going into details, the non-sequential mode isn’t really suited for PSF analysis. The definition of the aperture STOP isn’t built in the non-sequential mode. From your file, it isn’t obvious why you can’t use the sequential mode, is there a particular reason you want to be in non-sequential? There are ways you could get the PSF in non-sequential mode, but it is substantially more complex than just using the sequential analysis. You can have two models, a sequential one for analysis, and a non-sequential one for stray light analysis or whatever you need to do in non-sequential mode.

Does that make sense?

Take care,

David

Thank you for pointing this out and correcting me @Jeff.Wilde, I need to read about this feature. I guess in the non-sequential mode you have to control the source carefully, or at least sample it well enough, is that right? Would you use @David ‘s

to set it up with Gaussian quadrature?

Thanks for your help and take care,

David

Hi @David.Nguyen ,

The main source constraint is that it should be a point source (noting that a collimated beam is a point source at infinity, or alternatively, it derives from a point source in the front focal plane of an ideal lens) -- as it should be since a PSF is, by definition, the response to a point source.  As I’m sure you know, there are a number of NSC sources that meet this criterion.  With enough rays, random sampling over the area of the beam should be fine.  So, as Michael notes, no Gaussian Quadrature needed.

Hi @MichaelH ,

Interesting point about considering ray scattering.  Rays which are generated by scattering and splitting should participate in the coherent superposition process along with the specular source rays.  In OpticStudio, there is no phase shift associated with surface scattering/splitting.  As a result, all of the child rays that are generated by scattering from a given source ray arrive at the detector with close to the same incident angle but are laterally displaced from one another (this assumes the detector is a very small, so it only “sees” small-angle scattering).  Treating each ray as a plane wave, the net result is that these child rays, along with the parent specular ray, all correspond to essentially identical field patterns across the detector.  Equivalently, think of the child rays as emanating from the scattering point.  So this group of rays arrives at the detector like a spherical wave, but since the detector is very small, the solid angle, and hence the curvature, associated with the spherical wave is exceedingly small.  In this case, treating the specular + scattered ray bundle as a set of plane waves is fine.  Since the scattered rays are all phase correlated with the specular ray, as a group they add together and act just like the specular ray by itself.  You can see this by turning on surface scattering (on one or more surfaces) and observing no change in the Huygens’ PSF. 

More details for a specific example are attached.  

In reality, I expect that surface scattering probably does, in fact, effectively generate random phase shifts of the scattered rays relative to the specular rays.  (Assuming you want to think of a ray picture).  A wave model would be more rigorous, along the lines of what Goodman does in his book on speckle.  So, the fact that the Huygens’ PSF is scattering-independent seems like an artifact/limitation of the ray model as implemented in OpticStudio.

Regards,

Jeff