Diffraction Image Analysis can be performed using any of three types of transfer functions:  incoherent, coherent and partially coherent. When generating Diffraction Image Analysis using incoherent transfer functions, diffraction effects are accounted for, however, each point on the source is considered to be incoherent with respect to all other points. As such, spatial interference effects are ignored. When using coherent transfer functions, each source point is coherent with respect to all other points on the source.

For partial coherence, the situation is more complex. When using partially coherent transfer functions, each point on the source will have a different level of coherence with respect to each other source point. The degree of coherence between points is dependent upon a parametric function. In general, the closer two points are, the more coherent that they will be.

Partially coherent transfer functions are appropriate for many real-world sources. For example, in photolithographic applications, the typical sources used are not fully coherent. The effect of partial coherence on the imaging of a mark onto a wafer is very important.

Please download the attached file at the end of this article, “Partial_Start.zip”

Once you have downloaded this file, unzip it to any directory that you would like. Copy the BAR.IMA file to your {zemaxroot}/IMAFiles directory. Then, open the ZEMAX file “Partial_Start.ZMX”. This is a Cooke triplet photographic objective setup to work with on-axis light.