Optics: polarisation alignment

AI Thread Summary
Using a combination of wave plates in the sequence of half-wave, quarter-wave, and half-wave can achieve any desired polarization state. The first half-wave plate alters the polarization direction, the quarter-wave plate transforms linear polarization to circular and vice versa, and the final half-wave plate reverts the polarization direction. Proper alignment of the wave plates' fast axes is crucial for accurate polarization control. It has been determined that only two wave plates are necessary to produce any desired linear polarization, with the quarter-wave plate converting elliptical to linear polarization and the half-wave plate aligning it. Practical experimentation with the wave plates may provide clearer insights into their functionality.
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With a combination of wave plates in the order \lambda/2 - \lambda/4 - \lambda/2 it should be possible to achieve any polarisation. But I don't understand why: the first wave plate switches the polarisation direction, the second changes linear to circular polarisation and vice versa, and the last one switches it back again. How does this align the polarisation? :confused:
Thank you for any answers, or hints, or links.
 
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Thank you. I calculated the problem now, but the solution is lengthy and I guess it'll be easier to just try it out with the accordant waveplates :rolleyes: :smile:

I figured that I only need two waveplates to produce any desired linear polarisation. A quarter-wave plate will turn elliptical into linear polarisation, which can be aligned into the desired direction by the half-wave plate.
 
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