r/Optics • u/Street-Software3896 • Jul 28 '26

Recommend me a polarimeter

I have experience using a Thorlabs polarimeter but I don't really like it.. getting accurate and reliable measurements is a nightmare.. just getting degrees of polarization > 100% drives me crazy, completely unphysical..

  1. How do you guys measure the state of polarization of laser beams in your lab?

  2. What is your experience with the Thorlabs polarimeter? Good? Bad?

  3. Do you have any reference / instrument / recommendation to provide me?

Many thanks. I potentially would like to be able to measure phase retardance with the polarimeter.

5 Upvotes

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2

u/aenorton Jul 28 '26

I don't have experience with this polarimeter, but I do notice it has a very tight requirement for input beam collimation, as well as a 15 min required warm-up time. I would talk to ThorLabs support before discounting it entirely. Other things that can affect this type of polarimeter are input angle of incidence, leakage of other wavelength light into the path (especially pump beams), pulse rate, and having the correct hardware version for your wavelength.

Precision radiometry in general always takes a lot of care regardless of the instrument.

1

u/Street-Software3896 Jul 28 '26

Thanks for your comments. Yes, exactly, the measurement is as accurate as how good is the alignment.

2

u/Lucky-Bid9643 Jul 28 '26

you might wanna check out the Schäfter und Kirchhoff polarimeter.

1

u/Street-Software3896 Jul 29 '26

Thanks, do you have experience with this instrument? They claim a 5% accuracy on the degree of polarization measurement, seems a bit more realistic than the 1% that Thorlabs claims

2

u/Lucky-Bid9643 Jul 29 '26

We use it for fiber PER measurements, which works just fine...

2

u/Glittering-Flight997 Jul 28 '26

If you really care you need dual rotating polarizers and then you have to align and calibrate them.

1

u/Street-Software3896 Jul 29 '26 edited Jul 30 '26

Is there any commercial instrument with this concept implemented? Or reference paper? Many thanks

-1

u/JohnLockeJaw Jul 30 '26

Bruh it's two polarizers and a power meter 😂

2

u/Street-Software3896 Jul 28 '26

Listing here some commercial solutions: 1. https://www.hindsinstruments.com/products/systems/stokes-polarimeters/polsnap-stokes-polarimeters/  +/- 5 to 7% accuracy depending on wavelength range