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Ray aiming fails mirror tilts

  • 29 July 2022
  • 3 replies
  • 164 views
Davit.H

Dear community members,

I am curious if someone encountered similar problem and found a solution that does not increase substantially  the computational time.

The issue I have is when I try to tilt the mirror in already tilted system for tolerance purpose algorithm fails to fill the stop even with the use of ray aiming, floating aperture. I attach a simple model of tilted system using mirror and catalog lens, I have additional surfaces for tolerances. Rays are traced, better with ray aiming, however once I add for example 3 degree tilt about y or x in the tolerance coordinate brakes the rays are not traced.

Thank you in advance for your help.

Kind Regards,

Davit

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Best answer by Ethan 27 December 2022, 17:58

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Ethan
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Hi @Davit.H,

Apologies on the delayed response to your question. If I understand it correctly, you are wondering why the rays cannot trace after a certain mirror rotation angle. The reason is founded on physical principles. According to the law of reflection, the angle of incidence equals the angle of reflection for a flat/smooth surface, as shown below. Even ray aiming is not going to overcome this physical law (or else it becomes non-physical...). In your case, after a certain angle, the rays no longer hit the lens, stop, and image plane. When this occurs, OpticStudio lets you know that the system failed to trace because the rays simply shoot off into space (and are no longer meaningful). Are you meaning to move the stop/lens/image with the mirror rotation? If that is the case, then you don’t want to undo the coordinate rotation of Surface 7.

 

I hope this helps.

Best,
Ethan

Davit.H

Hello Ethan,

Thank you for your reply. Indeed, relaying on optical principles it should work, since I am using rather extended source with aperture floating by stop size. An example, if I tilt about x  27 ° using surface 2 it traces the rays, however, if say the tilt is 25 ° with same surface and additional 2 ° to match 27 ° using surface 3 (tolerance) I get an error “Cannot determine object coordinates”.

Hope this helps to better understand the issue.

Kind Regards,

Davit

 

 

Ethan
Rank
Userlevel 3
Badge +2

Hi @Davit.H,

The reason that Surface 2 has a different effect than Surface 3 is how you’ve set up the corresponding Coordinate Break. Surface 2 rotates the optical axis of the mirror and then rotates it again for the remaining elements (so it matches the condition for reflection). However, for Surface 3, you do the rotation for the mirror surface but instead of rotating the next elements to match the reflection path, you undo the rotation so that those elements remain fixed in angular space. With that set-up the beam can then move off of those surfaces into space (where OpticStudio fails to compute them).

 

Therefore, if you want to use Surface 3 to add an additional tilt to the axis in the same way, make the corresponding Coordinate Break be positive and match its angle. Something like this from your example:

 

Best,
Ethan

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