# Van Cittert Zernike Theorem and associated Optical phenomenon

Tags:
1. Sep 29, 2014

Hello colleagues

So I've been trying to make head and tail of a paper concerning coherence holography.
As I see it, it involves a sound understanding of the Van Cittrt Zernicke theorem
I have linked the paper below, and I was wondering if someone could explain the physics
going on behind and some mathematical pointers to help me understand it.

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-13-23-9629

Regards

2. Sep 30, 2014

### Andy Resnick

It can seem very abstract- let's start with this: do you understand what the 'mutual coherence function' is?

3. Oct 1, 2014

Hmm, so as I see it, the mutual coherence function is basically the average/correlation between two fields separated by a time (i.e. time of travel for some separation) t.
And it will be smaller for highly incoherent sources, but increase at very far ranges.

(Yeah, mainly wikipedia level, but just started readong about these topics, so still a newbie)

4. Oct 1, 2014

### Andy Resnick

Close- the mutual coherence function (MCF) is the correlation between two fields whose sources are separated in space and time. From the MCF you can extract both spatial and temporal coherence., and the MCF can be thought of as a propagating field.

Considering just the spatial coherence between two independent sources- the sources can be quasi-monochromatic- the field (from both sources) at points far from the sources will exhibit correlations arising during the process of propagation.

There is a good analogy between the van Cittert-Zernike theorem and diffraction from an aperture (Huygens-Fresnel principle).