Issue with Relative Illumination

  • 18 November 2020
  • 2 replies
  • 201 views
C

Hi


I'm building a model of a telescope and camera system, including some additional optical elements (e.g. lenses, mirrors, beamsplitters) on OpticStudio. Some of the things that I'm interested in using to evaluate the design are i) Field of View (or as I understood, the Relative Illumination), ii) spot size at camera, iii) losses in effieciency. I'm having some issues interpretting and the relative illumination results obtained from the model and I'm hoping if anyone could enlighten me.



I've taken a look and read this document here on how Relative Illumination is calculated and the various problems that one may encounter in hindering the calculation. But I'm not clear where is the origin of the abberation, which I believe, that's causing the this behaviour seen here.



The backview layout of the optical elements.



A zoomed in version where we ignore the first fold mirror in the layout.


There's obvious clipping at the last lens and at the block (the beam splitter), but I'm unclear why is there a gradual increase in the relative illumination between field angles of 0 degrees and 0.03 degrees.


Please advise!


 


Thanks and Best Regards


Clarence Liu

2 replies

S
Rank
Userlevel 6
Badge +2

Hi Clarence


It is not clear to me how your object is imaged. It would be easier if you could share your file. Please feel free to open a Case to do so or send an email to support@zemax.com instead of using the forum as then it will not been seen by everyone. 


The common things we recommend first about Relative Illumination are:




  • Use a recent version of OpticStudio: 20.1 or later versions. 




  • Make sure 'Use Polarization' is checked, especially if you compare your results with other softwares.




  • Try higher sampling for ray density. 




Sandrine


 

Sandrine Auriol
Mark.Nicholson
Rank
Userlevel 7
Badge +3

Hi Clarence,


I agree with everything Sandrine says, and to your specific point I'm unclear why is there a gradual increase in the relative illumination between field angles of 0 degrees and 0.03 degrees, I'd say look at the distortion plot.


If you look at the grid distortion plot, I'd expect to see a higher ray density at that field point relative to others. Distortion is the only aberration that has a systematic effect on the RI plot, unless the lens is sufficiently aberrated that the restrictions described in the manual come into effect.


- Mark

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