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Top Hat - collimated beam optimization

  • 3 November 2022
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Dear Zemax community,

I am building upon your 'How to design a Gaussian to Top Hat beam shaper' tutorial. I additionally want the top hat to be collimated over a 30cm propagation distance.

I setup the system with two aspheres and an optimization macro that squares my beam (REAY operand, as in the tutorial) and subsequently collimates it with the RANG operand (target is 0 angle). However, it fails to maintain the top hat shape and collimation over the propagation distance. Am I using the wrong operand to collimate, or should I use the constraints with two dummy surfaces (at a distance of 150mm (MIDPOINT) and 300mm)? 

 

Any suggestions are welcome and appreciated.

Thank you very much, Paul

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Best answer by Sandrine Auriol 14 November 2022, 16:55

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Hi Paul

Your merit function contains 2 blocks:

  • one to target a uniform / top-hat beam on the image plane
  • one to target collimated on axis rays

This looks correct to me. You could swap the second block with a default merit function and target an angular radius:

So I guess that if it is not working it may be because of the varialbles, maybe the system doesn’t have enough degrees of freedom.

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