In the system explorer, “Units” section, you can switch the “MTF Units” from Cycles/millimeter to cycles/milliradian.

Cycles is the same as line pair.

Thankyou for your reply.

Actually, I am trying to simulate resolution of night vision objective with II Tube with 64lp/mm resolution with SNR 22.

Thanks

You will read this value in the MTF plot. The MTF is defined as:

For OpticStudio, modulationobject = 1

So 

The MTF plot will give this value for a range of frequencies (cycles or lines per mm). 

For more information about the MTF, have a look at Edmund Optics website: https://www.edmundoptics.co.uk/knowledge-center/application-notes/optics/introduction-to-modulation-transfer-function/