Example1 : 

Through focus spot diagram/Through focus MTF is the handy tool that can be used in imaging system analysis to quickly assess the performance of an imaging system as the image plane moves back and forth. MTF (Modulation Transfer Function) is a measure of the ability of an imaging system to transfer contrast at different spatial frequencies from the object to the image, and it is often used as a measure of system resolution. The lower the MTF, the less resolution the system can obtain at specific frequencies. In other words, if a lower MTF value is used as the limitation of human perception of sharpness, the corresponding frequency can be calculated when the image plane is moved at that specific MTF value. In the example below, MTF=0.2 is the threshold metric used for the evaluation.

Two macros are defined: 

• ZPL06.ZPL
• Through Focus Frequency.ZPL 

ZPL06.zpl is a macro that can be added to the Merit function editor as ZPLM. The purpose of this macro is to transfer a (dummy)parameter, specifically frequency, from LDE into the input parameter for an optimization operand. The parameter is further optimized in the second macro.

Example of using Double Gauss 28 degree field.zmx file: 

1. Remove all variables through Optimize> Remove All Variables 
2. Insert new surface before surface1 
3. Set Conic of surface1 as variable 

Run the second macro: