Is it possible to control phase of a light radiation? Assume I have two point sources A and B. They emit spherical waves of a green light (or any other color). Is it possible to make such physical system where the phase of B is shifted by some $\theta$ in comparison to A.
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2$\begingroup$ Simply vary the distance traveled by moving the light sources. $\endgroup$– Hans WurstCommented Mar 20, 2022 at 13:49
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2 Answers
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The challenge is to make two sources that are highly coherent but spatially separated. The easy ways to do that generally involve starting with a single source and splitting its output (for example with beam splitters, partially reflective mirrors, or fiber optic couplers) and routing the beams to different locations.
If creating your "two" point sources that way is acceptable in your scenario, then varying the phase of one or both sources is usually easily accomplished. For example, you can use moving mirrors to physically vary the length of the path from your beam splitter to one of the source locations, or you can vary the optical length of the path with something like a lithium niobate phase modulator.
answered Mar 20, 2022 at 15:45
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For example, a spherical shell with controlled refractive index around B.
answered Mar 20, 2022 at 13:46