Hi,

Regarding your remark on ray aiming in sequential mode, using the Ray Aiming Wizard is most advised. I would be very wary of -- except for systems where the STOP comes first -- turning off ray aiming.

Regarding non sequential mode (not hybrid), if you want to use an image like in sequential mode, you should use the Slide object, give it a material (glass) and place a collimated source just behind, with same size.

Once this is done, you make the Slide scatter Lambertian, scatter fraction 1, 1 scatter ray:

 and set the Importance sampling to target the first lens of your system, with a Size similar to that lens size

You should be able to see your image if you check the “Scatter NSC Rays” in the Ray Trace Control window

The ray splitting can give you some ghost, so you may want to check it too, but splitting thresholds are an advanced topic.

Yes, I’m familiar with the basic procedure for setting up importance sampling. The issue is that the fisheye lens’s aperture stop is positioned far behind the first lens and is significantly smaller. So, if I set the first lens as the target for importance sampling, the efficiency will always be poor. Is it possible to set up a dummy plane as the importance sampling, I can move that when I need to simulate different angle illumination into the fisheye lens? I have done this in lighttools. Not sure if I can treat a dummy plane as a importance sampling object in Zemax. I know how to move the dummy plane in python API. could you just help me to set up a dummy plane as importance sampling target.