Hi Robert,

Thank you for your post!

As far as I know, the Kholer illumination system is usally arranged as something shown below. 

If you want to simulate the image formed by the system, you can use the Image Simulation tool in Sequential mode. However, the Image Simulation tool places the input scene or the source bitmap at the system Object plane, but in a system like above, the Slide or film is not located at the object plane but at an intermediate surface. You can certainly separate the whole light path into two systems to model, the illumination part and the imaging part. In the imaging part, you can place the bitmap Slide at the object plane, move the image surface location, and use the Image Simulation tool to model the depth of focus effect. Alternatively, you can also set the whole system up in Sequential mode and then convert to Non-Sequential mode. In Non-sequential mode, you can place a Slide object anywhere in the system and use Detectors to observe the simulated image. We have a sample file showing how to use the Slide object in NSC mode at \Documents\Zemax\Samples\Non-sequential\Sources\Slide Sample.zmx.

Regarding your second question on evaluating the angle of incidence of rays on the sample, you can use operand such as RAID to return the marginal ray angle of incidence on the sample. This will give you an idea of the NA of the cone incident on the sample surface. 

Additionally, our engineer Kats has created a learning path on Illumination System Design which might be helpful. You can find the learning path at https://my.zemax.com/en-US/learning-paths/illumination-system-fundamentals/. 

Let me know how these thoughts work for you or if you have any other questions. 

Best regards,

Hui