Sequential Skew Gaussian - inputs with astigmatism and non-ideal M^2?

  • 15 April 2021
  • 2 replies
  • 138 views
D

I haven’t used the Skew Gaussian feature in Optic Studio (sequential mode) in a long time, but I have a memory that the input beam parameters once included the M^2 values for the Gaussian, and some formulation about the Embedded Gaussian. Did you remove these features?


Now the inputs are:


Wx, Wy, Surf to Waist, wave, field, start, end [implies possible ellipticity, but zero astigmatism]


Whereas more generally one would like to see


Wx, M^2x, surf to Xwaist, wave, field, start, end


And


Wy, M^2y, surf to Ywaist, wave, field, start, end


So that the input could have both astigmatism and ellipticity and non-ideal M^2 for the inputs and outputs both. Please tell me if my memory is faulty. I remember that the Embedded Gaussian definition was a little tricky, and I imagine a lot of customers got confused on this point. So maybe you pulled it?


I can think of some workarounds with either the Merit Function editor or a macro, but having more fields in the input dialog box would be simpler still.   My problem of the moment is not really general skew gaussian , but just XY separable assymetry. 


Thanks.

2 replies

S
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Hi David


I have checked in an older version and it doesn't contain the M^2 parameter either. The M^2 parameter is given in the Paraxial Gaussian feature and indeed the waist is defined for an embedded gaussian beam (M^2=1). 


I think all I can suggest right now are workarounds. Let us know if you need help on that. We have a feature request on this so I will add a vote on your behalf.


Sandrine

Sandrine Auriol
Csilla Timar-Fulep
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Userlevel 5
Badge +2

Hi David,


Thanks for your post here on the forums!


The M^2 factor is an input parameter for the Paraxial Gaussian Beam tool, but unfortunately not for the Skew Gaussian Beam tool.


This has been brought up by other users before (to add separate M^2 values for X and Y to the Skew Gaussian Beam tool), and we have an open feature request for it in our internal system. Tank you for bringing this topic to our attention again. I have gone ahead and added your vote to the feature request.


Please keep in mind that feature requests are weighed based on impact, difficulty to implement, and the number of users who request it. A request is not a guarantee that the feature will be added to a future release. However, these feature requests are very important to us and shape the future of OpticStudio, so we appreciate your input regarding desired functionality.


Regarding the calculations for Embedded Gaussian beam, it is discussed in detail in the Help system under the description of the Paraxial Gaussian tool.

We have recently updated the Help files, please have a look at: 

The Analyze Tab (sequential ui mode) > Laser and Fibers Group > Gaussian Beams > Paraxial Gaussian Beam

There is also a section about how the M^2 quality factor modifies the beam properties.


Regarding the astigmatic beam modelling, the Skew Gaussian Beam tool only allows the initial beam to be launched from a single “Start Surface”, at the same z location. You can launch the beam with different X and Y waist sizes, but the beam is launched on the same surface, or the beam X and Y waists are placed on the same surface. So, yes, you are correct, this enables possible ellipticity, but zero astigmatism.

For more information, please check out the Help at:

The Analyze Tab (sequential ui mode) > Laser and Fibers Group > Gaussian Beams > Skew Gaussian Beam


If you would like to model an astigmatic Gaussian beam, then maybe you could use the POP tool, where you can define an Astigmatic Gaussian beam type:



You may find more information about the different option for defining the initial beam in POP in the Help system at:

The Analyze Tab (sequential ui mode) > Laser and Fibers Group > About Physical Optics Propagation > Defining the Initial Beam


I hope this helps, but if you have any further questions, please let us know and we will be happy to help!


Best,

Csilla

Csilla Timar-Fulep

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