Hello Jeff!
I know it's been about a year since your post but I'm also interested in modelling a similar optical black coating on a baffle for a telescope. 
Did you get your model to work?

Thanks,

André

Hi Andre,

Thanks for your question here!

If you want to model black painted surfaces you need to use a coating. You can choose a coating from our library, or you can create a new one. If you have no data available, you will need to make an estimation as best as you can. You can use MIRROR material, so that light reflects from it, and then you can use a coating to define the reflectivity. The easiest solution would be to use the IDEAL coating with a defined reflectivity and loss. The syntax for this is the following (anything that is not transmitted or reflected, is absorbed):

IDEAL Transmission Reflection TIR

If you need a more complex model with wavelength or angle of incidence dependent response, you can define a TABLE coating.

I would suggest to check out these knowledgebase articles about how to define and apply coatings:

How to define metal materials in OpticStudio · MyZemax

How to model a dichroic beam splitter · MyZemax

How to model a partially reflective and partially scattering surface · MyZemax

How to add coatings and scattering functions to Non-Sequential objects · MyZemax

If you have any further questions, please let us know and we will be happy to help.

Best,
Csilla

Hello Csilla,

Thank you, that's exactly what I was looking for!
Just for future reference, I'm trying to achieve a behaviour similar to the image below.

If I correctly understood the references you posted, I need to create a baffle with a mirror material, create and add the following ideal coating:
IDEAL BaffleCoating 0 0.05

And then apply a Lambertian scatter model with a scatter fraction of 0.32 (32% of the reflected 5% to achieve the 1.6% shown in the image).

Best regards,
André Santos

Hi Andre

Yes correct. You can use an ideal coating I.95 on a mirror. 5% will be reflected and the rest absorbed.

Then as you said, you can use the scatter fraction.

So 5% x Scatter Fraction = 0.32 = 1.6% will be scattered

And 5% x (1 - Scatter Fraction) = 3.4% in the specular direction.

Sandrine

I face a similar problem as Jeff Kuhn did about 4 years ago, but did not find a solution in the many replies to the post. I’m a beginner trying to simulate an integrating sphere, taking off from the very simple sample file “Integrating Sphere.zmx” in “Zemax\Samples\Non-sequential\Miscellaneous”. My aim is to model the sphere efficiency with weakly absorbing lambertian scattering surface and I tried to apply a coating to the sphere object with an IDEAL coating “IDEAL R95 0.05 0.95” combined with Zemax’s standard “Lambertian” scatter model which should give a drastic reduction of the efficiency compared to a 100% reflecting coating due to the many scattering events taking place inside sphere, but this does not happen. Is my problem perhaps  (as somebody suggested) related to to the sphere being modelled as just a surface instead of a solid object?

Henrik Fodgaard