Hi Weihua,

Thanks for your question here!

To help you get started, please check out these references about MTF calculations:

How to Measure MTF - Optikos

Introduction to Modulation Transfer Function | Edmund Optics

Math Magic And MTF A Cheat Sheet For The Vision System Community (photonicsonline.com)

I hope this helps, but if you have any further questions, please let us know and we will be happy to help.

If other Zemaxers have working example they would like to share, please do not hesitate to do so.

Best,

Csilla