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I want to build an interferometer. In order to do so, I need to buy some optical components, such as beam splitter cubes. These beam splitter cubes, and other optical components, come in a polarizing and a non-polarizing form. Do interferometers require polarizing beam splitters, or do they require non-polarizing beam splitters? Based on my research, I don't really see any mention of needing polarizing optical components, so I suspect that interferometers generally use non-polarizing optical components (outside of, perhaps, unique circumstances).

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    $\begingroup$ When you bring the two beams back together, what is the impact if you have polarized the two beams in different ways? $\endgroup$
    – Jon Custer
    Jul 20, 2021 at 16:41
  • $\begingroup$ Consider a perfect beam splitter that makes one beam perfectly horizontally polarized and the other one perfectly vertically polarized. $\endgroup$
    – Jon Custer
    Jul 20, 2021 at 16:52
  • $\begingroup$ @JonCuster It seems clear to me that they would cancel out when coming back together, no? $\endgroup$ Jul 20, 2021 at 16:55
  • $\begingroup$ You probably want non-polarizing beamsplitters. That said, for some applications you might want polarizing beam splitters. What is your purpose for building an interferometer? $\endgroup$
    – Jagerber48
    Jul 20, 2021 at 18:21
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    $\begingroup$ @ThePointer yes, should be easier with non-polarizing components. If possible, you can put a photodetector at BOTH output ports of the re-combining beamsplitter so that you can capture 100% of the light. This will increase your sensitivity by at least $\sqrt{2}$ if you analyze the two signals appropriately. $\endgroup$
    – Jagerber48
    Jul 20, 2021 at 18:49

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Using polarising beam splitters will produce polarisation fluctuations at the output ports. The polarisation of a single output will vary from linear to circular with a phase shift between the two arms of the interferometer. Normally we measure intensity fluctuations between the two output ports, this requires non-polarising beam splitters.

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    $\begingroup$ Ahh, I thought so. Thanks for the clarification. $\endgroup$ Jul 20, 2021 at 17:33
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Use non-polarizing beam splitters if you need to ask.

But if you understand polarization and interference, then by combining polarizing beam splitters and waveplates you can also achieve most effects, and for some applications this is a good way to proceed.

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Since a laser is the light source, you are starting with polarized light to begin with! If you used polarized filters you might just cut all the light.

Also for a simple interferometer see this link https://www.nist.gov/image/interferometer-compositejpg

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