Hi Ahmed,

You may find more information and sample files about the two common applications of microlens arrays that David mentioned here:

For 1) to increase the collection of pixelated detectors, please see the Lenslet Array sample file in the \Documents\Zemax\Samples\Physical Optics folder. This example also shows how to describe lenslet arrays in fully sequential mode using the us_array User Defined Surface DLL. 

For 2) homogenization, please see this knowledgebase article about how to model microlens arrays in non-sequential mode:
Fly’s eye arrays for uniform illumination in digital projector optics – Knowledgebase (zemax.com)

Best,
Csilla

Thank you both for the answers.

I guess for imaging applications it has to be something like a GRIN lens array (see for instance SELFOC lens arrays).

I know there is Gradient surface types in sequential mode, can those somehow be made as a periodic array? Refractive index information appears to be lost when converting these into NSC mode where it would have been possible to make them into arrays.

Best,
Ahmed