- #1
Chen
- 977
- 1
Hi,
I'm constructing an interferometry experiment, in which I'm using a Michelson-Morley-type interferometer. However, the only beam splitter I have which preserves polarization is physically small (a few mm), and so in my setup the beam in each arm is not split. The reflection off the mirror is completely, or extremely close to, normal. The input beam is linearly polarized.
I'd like to have the polarization plane of one of the beams reflected through some axis (doesn't matter which), with respect to the polarization of the beam in the second arm. Normally I'd use a half wave plate for this purpose, however since I can't split the beam in each arm, it would pass through the plate twice and the final result would be the same as if I had no plate at all.
So I thought, why not use a quarter wave plate instead? After the beam splitter, one of the beams would pass through the plate and change its polarization to something elliptic (because the polarization along one axis would gain a phase of pi/2). That beam would be reflected off the mirror, and pass through the plate again, and the polarization along the same axis would gain an additional phase of pi/2 and the total effect would be just that of a half wave plate.
However, I'm not sure that it would work, because in its second pass through the plate, the beam would be going in the opposite direction. So I thought it might be the case that the polarization which gained a phase of pi/2 in the first pass, would lose it in the second pass, and not gain an additional pi/2. Do you think that's the case? The material I'm using for the wave plates is Mica, optical quality.
Any input would be most welcome.
Thanks,
Chen
I'm constructing an interferometry experiment, in which I'm using a Michelson-Morley-type interferometer. However, the only beam splitter I have which preserves polarization is physically small (a few mm), and so in my setup the beam in each arm is not split. The reflection off the mirror is completely, or extremely close to, normal. The input beam is linearly polarized.
I'd like to have the polarization plane of one of the beams reflected through some axis (doesn't matter which), with respect to the polarization of the beam in the second arm. Normally I'd use a half wave plate for this purpose, however since I can't split the beam in each arm, it would pass through the plate twice and the final result would be the same as if I had no plate at all.
So I thought, why not use a quarter wave plate instead? After the beam splitter, one of the beams would pass through the plate and change its polarization to something elliptic (because the polarization along one axis would gain a phase of pi/2). That beam would be reflected off the mirror, and pass through the plate again, and the polarization along the same axis would gain an additional phase of pi/2 and the total effect would be just that of a half wave plate.
However, I'm not sure that it would work, because in its second pass through the plate, the beam would be going in the opposite direction. So I thought it might be the case that the polarization which gained a phase of pi/2 in the first pass, would lose it in the second pass, and not gain an additional pi/2. Do you think that's the case? The material I'm using for the wave plates is Mica, optical quality.
Any input would be most welcome.
Thanks,
Chen