Question

Ray artefact at 45° object angle in my lens design

  • 27 June 2024
  • 9 replies
  • 145 views

Dear All,

 

I see an artefact in rays being projected from 45° to the first lens surface.

One of the rays does not hit the lens surface as shown here:
 

The first surface is a dummy surface because object distance is infinity.

The spot diagram show a radius of about 1200 µm whereas the spot radius for other object angles is between 4 and 9 µm. Surprisingly 40° and 50° object angle rays do not have same behaviour. 

 

Is there a way to rectify this or maybe ways to find sources of this artefact?

 

Any suggestions are welcome.

 

Regards,

Amit

 

PS: For confidentiality i could not add an image of the entire cross section of the objective design.


9 replies

Userlevel 4
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Assuming this is a sequential view, have you checked “delete vignetted” option in your view settings ?

 

Hi Ray,

 

if i  have “delete vignetted” selected it solves the issue in the ray propagation but does not solve the spot diagram issue:
 

 

Userlevel 4
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Hi Amit,

 

Perhaps a floating aperture on the surface(s) where the ray should be cut could help.

 

Hi Ray,

 

thank you for your response. I tried floating apertures individually on most of the surfaces. It does not work.

Userlevel 3
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Have you fixed the front lens Diameter? OR specified s user defined CA?

 Hello Chandan,

Have you fixed the front lens Diameter? OR specified s user defined CA?

yes the first surface has a user defined circular aperture.

Could you please elaborate how that has an impact?

 

Amit

Userlevel 6
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Hi Amit,

I suggest a few things you might look at:

Turn Real Ray Aiming on.

For aperture in the System Explorer, check the settings:

  For Float by Stop Size, make sure the stop is where it should be. Try small values of semidiameter     on the stop surface.

  For Image Space F/#, Check the value. Try large values for a slower system.

  For Entrance Pupil Diameter, try smaller values.

 

Userlevel 3
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Hi Amit,

If you have restricted the diameter of the lens, it will now allow the lens to adjust the diameter as per your system requirements and therefore with fixed diameter you may not be able to launch the full beam width leading to vignette. To avoid the same it is suggested that fix the lens diameter one the design is complete or control the lens diameters using merit function. Once the optimization is done you can fix the lens diameter.

If lens diameter is fixed and you can not increase it further try the suggestion from @David to adjust your beam diameter.

Thanks.

Userlevel 6
Badge +4

Hi Amit,

This article might relate to the issue: How to Use Ray Aiming

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