Question

How to "freeze" a surface in zemax.

  • 31 July 2023
  • 5 replies
  • 77 views

This is probably a very trivial thing. I am trying to keep a surface from moving as I scan a ray across it, but every time I do it, the surface follows the ray and displaces in X and Y to keep it at its center. Any ideas what to do here?


5 replies

Userlevel 3
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Hi Apbraga,

Can you elaborate on the question a bit more as it is unclear?

Are you trying to keep your scanning surface stationary without tilt and decenter while rotating the scanning mirror? Only you want to shift the beam on different parts of the scanning surface?

 

Thanks.

 

hi Chandan,Maurya,

 

I have an optical system that is point a beam to a mirror. I want to de-center the beam in XY to hit the mirror at different places (not angles), but as I do that, the mirror is automatically re-centering the incoming beam. I thought that that would only happen if I set the XY de-centers on the surface’s coordinate breaks to “chief ray solve” (I am using coordinate breaks before and after the mirror surface), but apparently not. I am trying to find a way around it, unless I am missing something very obvious…

 

thanks,

 

-Alex 

Userlevel 6
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If you are using x y settings on the first coordinate break to move the mirror, the coordinate break after the mirror should use pickup solves referencing the first coordinate break to make its x y shifts the negatives of the first.

Userlevel 5
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Once I practiced and became comfortable with using it, I like the Coordinate Break, Tilt/Decenter, Coordinate Return, To Surface method better.  You insert a dummy reference surface before your mirror, then set Tilt/Decenter to “Orientation, XYZ”, and the “To Surface” value to the reference surface.  You have to be careful to get your dummy reference surface exactly where you want to return to, including positions and tilts.  It’s worth practicing on a few cases.

Hi @Mike.Jones ,

 

Thank you for your reply. I’ve tried doing what you recommended but the surface of the mirror continues to move along with the ray that hits its center. For example, if I move the ray vertically by 20mm, the mirror will also move vertically by the same amount. I suspect that there must be something, somewhere, that I am missing. Perhaps something needs to be ‘checked’ (or unchecked) on the definitions of the surface (?).

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