This is sort of a followup to an earlier question that I posted regarding how to destroy the temporal and/or spatial coherence of a laser beam. It was suggested to me that I could use a rapidly rotating sheet of ground glass through which I pass the later, which seems useful but a little bit complicated (and it can only destroy the coherence down to a certain point, as mentioned in the comments). This made me think: why couldn't I just pass the laser beam through an oil emulsion instead? Light travels about 14% slower in oil than in water, and I have read the the average oil droplets in an emulsion have a wavelength of 10 um or so, so it seems like the path-length differences created by having some photons travel through oil droplets while others do not would be more than enough to destroy the temporal coherence of a visible-frequency beam. Moreover, it seems like passing through oil droplets would also cause the beam to bend repeatedly, destroying some of the spatial coherence as well.
Am I on to something here? Or do I really need to go with the ground glass in order to achieve optical decoherence?
