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Hello,

          I am setting up an optical system with a CAD object with unknown curvature and I want to determine where a baseline ray and a ray at some other field angle crosses.  I would like to do this to generate a “best focus range” so I may determine the best position for a reflective flat surface.  I can manually find these points, but is there a way to find these points using an operand or some other feature?

Method:

I first define a point where three Source Ray sources are positioned incident on the CAD object.

I use one of the rays to be the baseline ray to find the focus.

I then want to find where the baseline ray crosses with the other two rays as these will be two different points.

 

Thanks for the help.

If you have some idea where the rays will meet, the most straightforward method would be to use three sources each emitting a single ray representing the fields, and then put a detector roughly where it should go. Ideally, all three will initially hit the detector. Then you can use the optimization wizard to get a minimum spot size with full power using the X, Y, and Z positions as variables. If the system is a regular symmetric imaging system without folding, you may just need to vary the Z. Use a detector with a fine resolution so you can get good accuracy.

If you want to do them one at a time, just do it with two rays first, and then another two rays, perhaps with two configurations that turn off one or the other of the rays.


You might also try hybrid mode NSC and use the Power Pupil Map/Power Field Map features.


If you have some idea where the rays will meet, the most straightforward method would be to use three sources each emitting a single ray representing the fields, and then put a detector roughly where it should go. Ideally, all three will initially hit the detector. Then you can use the optimization wizard to get a minimum spot size with full power using the X, Y, and Z positions as variables. If the system is a regular symmetric imaging system without folding, you may just need to vary the Z. Use a detector with a fine resolution so you can get good accuracy.

If you want to do them one at a time, just do it with two rays first, and then another two rays, perhaps with two configurations that turn off one or the other of the rays.

HI kevin,

                Thank you for the reply.  That is currently what I am doing as this is an off centered parabola that has astigmatism.  I have three foci due to the three rays I am tracing through the system.  I will implement the optimization operands to more finely determine the ray crossing.

 

Thank you much for the help.


You might also try hybrid mode NSC and use the Power Pupil Map/Power Field Map features.

I only have the parabolic curve from the CAD object unfortunately.  I do not have the parabolic equation parameters they used.  Is there a way to back calculate this from NSC to SEQ, and back to NSC?

Thanks in advance for the help.


Well, that’s what the Power Pupil/Field maps do. You trace a central ray at some field and pupil coordinate, and then trace a ring of 12 rays around it. It then computes where each ray crosses the reference, or the point of closest approach if the rays don’t actually cross, and then computes focal length/power as seen by the central ray. Check out the docs in the Help file, I think this may be what you need.

  • Mark

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