Hi Gabriele,

I think you must have some sort of alignment error.  Coma is an off-axis aberration (in this case, meaning angularly off-axis, i.e., an input beam with a relative tilt compared to the optical system) -- and OAPs are notorious for being sensitive to alignment and/or off-axis use.  I put together a replica of your system and don’t see any aberration.

Here an off-axis aperture is placed on surface 1, and vignetting factors define the corresponding apparent entrance pupil:

If you can attach a version of your model, that would help with debug.

Regards,

Jeff

Hello Jeff,

Thanks again to help me.

I Implemented the solution as from your Lens Editor and it works.

I wondeer anyway why my version doesn’t work. I cannot share the lens editor unfortunately because of restriction policy but fundamentally I do not implement a stop aperture but I declare immediately the aperture of the beam in the system explorer.

Then I use the Tilt decenter of the OAP 1 to shift the parabola vertex down and then I place the OAP2 in a coordinate breake to shift alogn y  it and turn to get the two focal point coincident using RAID=0 degrees  as opimization criterion.

Once finished it seems  all ok but as you saw the system looked misaligned. Have you got a clue why this way does not bring to the desired result?

Thanks again

Gabriele

Hi Gabriele,

I’m not sure if I completely understand your approach.  Without seeing your model, it’s difficult for me to say what might be happening, other than there is some sort of alignment problem.

If you don’t want to use vignetting factors, then you can simply specify the desired input beam size (using system aperture settings) and shift the entire optical path down in the y-direction with a coordinate break:

Regards,

Jeff

Hello Jeff,

You understood very well my point and it seems that for you is not a problem to make it working.

I have to see what is the bug in my model. Unfortunately as I said I cannot share too many details.

Thanks anyway I can go further now.

Bests

Gabriele