I would like to cause a phase shift in light. I would prefer to do so by varying the voltage to the phase shift device. Is there any existing system or any suggestions? We had a bit of difficulty with this one. I dropped a few decimal points or something. Lets try this one more time. I am looking for a technique to cause a variable phase shift or delay in a yellow (580 nanometer) light beam. The modulation frequency is in the order of ten megahertz, the shift need only be a minimum of two wavelengths of the yellow light.