Hi Joerg

The POP beam is always centered and perpendicular to the chief ray at a given field / wavelength.

But the receiving fiber position is defined under the Fiber Data tab in POP. You can position the Fiber vs the Chief Ray or vs the Surface Vertex, and you can also decenter it. 

Let us know if that helps.

Sandrine

Hi Sandrine,

unfortunately nothing changes the appearance of the beam.

I would expect the beam center 'shifting'?

Best, Jörg

'perfect' alignment of receiving fiber:

with 5 um offset by coordinate break right before image surface:

With decentering of the receiving fiber in the POPD settings menu:

Hi Joerg

The apparence of the beam won't change with a coordinate break as the POP beam is defined on an array that is centered and perpendicular to the chief ray. The coordinate break has no effect on that. However you will see the effect in the POP ribbon in the coupling as the receiving fiber is positioned differently:

- Coordinate break 6: Decenter Y = 0

- Coordinate break 6: Decenter Y = 0.005

Let us know if it helps.

You can also use the Decenter X and Y of the Fiber Data tab in POP.

Sandrine

Hi Sandrine,

yes, that was my impression. I see all you describe as well.

I was hoping that the setting in the Fiber Data tab in the POP settings would have an impact on the 'picture'. It has not...

Of course the coupling efficiency is calculated correctly.

Thanks and best regards

Jörg

Hello, 

I was dealing with the same issue as the OP in this topic. Nevertheless, in the latest Zemax version POP seems to also ignore coordinate breaks w.r.t. the coupling efficiency change.. 

For example, I am modeling fiber coupling from an imported source. I clearly see changes in the coupling efficiency if I set the “Decenter” parameter in the POP window. However, if I place the a coordinate break with the same decenter before the image, the efficiency value doesn’t change at all. So basically what @Sandrine Auriol showed above is not happening to me. I guess this could be a bug in the latest version or am I missing something?

I do not necessarily need to use the coordinate break but I would like to set the position of the fiber as variable w.r.t. the optimization. Coordinate breaks seemed like an easy way to do so but since this does not seem to work, is there any alternative option?

Thank you in advance.

Marek