Physical Optic Propagation analysis

  • 21 December 2020
  • 7 replies
  • 471 views

Hi everyone, I need your kindness help for some problems that I had during analysis using physical optic propagation. I don’t know whether my system is good or not, but I believe can analyze or optimize my system to be better.


I had 3 questions that I would like to ask. I use prop report in POP to see each of the surface in my system.



  1. What mean by using outside to outside propagator. Is I need to check anything like I tick the use angular spectrum so that my surface become using inside to inside propagator? Or is there another way to solve it. Or I just have to ignore it.

  2. Sampling is too low. I use resample after refraction so that I can increase the sampling. Are there any ways so that I can keep the original sampling without increasing it?

  3. Inadequate guard band detected. My system shows this warning, and I did not know the ways to solve this problem. Is there any ways that I can use in order to solve it?


I am sorry for asking that kinds of problems because I am a beginner in using Zemax. If anyone can help me in order to solve the problems, I really appreciate for your kindness.


Thank you.


7 replies

Userlevel 3
Badge +2

Hello,


POP is quite an advanced an complex feature in OpticStudio and so it is difficult to give specific guidance on resolving problems with your system without be able to see it. However, the best general advice I can give it to read in full the section of the OpticStudio help files 'About Physical Optics Propagation'. This provides lot of essential detail on how this feature works and can save a lot of time in future.



There are also a number of useful Knowledgebase articles that can subsequently help you debug problems systems.


Using Physical Optics Propagation (POP), Part 1: Inspecting the beams · MyZemax


Using Physical Optics Propagation (POP), Part 2: Inspecting the beam intensities · MyZemax


Using Physical Optics Propagation (POP), Part 3: Inspecting the beam phases · MyZemax


I hope this helps. If you are able to share your file then we can take a look for any obvious issues.


Thanks,


Chris

Userlevel 6
Badge +4

There is also an excellent knowledge based article called Using Physical Optics Propagation.  I recommend carefully studying all three parts of this article. It is especially useful for understanding beam sampling requirements and issues.

Userlevel 6
Badge +2

Thank you David.

Thank you, Mr. Chris and Mr. David, for the answers and suggestions. I had looked on it, but I still have same problems. I attached my system file below, please have a look on it.


So, the first problem is about using outside to outside propagator as shown in below.



It is okay with the system? or did I have to do anything like optimize or somethings that I did not realize. Actually, I tick the angular spectrum propagator as shown below to make my system using inside to inside propagator. Is it true optimization to use in this system?



Then I realize when I use the angular spectrum propagator analysis in certain surface, a warning shown like below is appeared. Is there any solution to solve this problem?



Next problem is, I put a grid phase into the system and analyze the surface and this warning is appeared. Is there any solution regarding this problem?



I really hope for your kindness help, maybe there is something wrong with my system that I did not realize or not have enough knowledge about it.


Thank you.


 

Userlevel 6
Badge +2

Could you please update the file with the modifications from https://my.zemax.com/en-US/forum/threads/d23062df-ed44-eb11-a813-000d3a329613?


 

Userlevel 3
Badge +2

Just to add to Sandrine's comment, I can say that the use of the outside to outside propagator is not unusual. OpticStudio will automatically choose the appopriate propogator based on whether your beam is inside or outside the Rayleigh range (see the 'Propagating In and Out of the Rayleigh Range' section of the help files). You should only override this choice with the 'use the angular spectrum propagator' setting if you have a specific reason to do so.


The reason for the 'Inadequate guard band' error is that you POP beam sampling grid is too small at that surface. You need a regain of zero intensity/blank space around you beam to prevent aliasing effects. When you use the 'use the angular spectrum propagator' setting at all surfaces the the POP grid will not change size as the beam size changes which could result in the beam growing larger than the gird adn this error message occuring.


For the '...too many waves of phase...' error. I would suggest increasing the POP sampling (currently 256x256) to see if that resvolves the issue. As you have a grid phase surface in the system you should ensure that the POP sampling is at least high enough to properly sample the highest frequency phase variations on you grid phase surface.


Are you able to share what the expected output for this system is? Is it some kind of dot projection?

Thank you Ms. Sandrine and Mr. Chris for your kind help. I really appreciate for the answers and explanations you give to me. For my system, its seem to be more better than before. If I have another problems, i will forward in this forum soon. Thanks again.

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