PHYS 201 | Phase Retarder 1 - Birefringence
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- Опубліковано 3 гру 2024
- A phase retarder affects polarization through birefringence - anisotropy in phase velocity rather than in absorption, as was the case for the linear polarizer.
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In your description at 3:18, do you mean circular vs elliptical? Since your first light beam is not polarized?
Are you describing unpolarized light at the beginning before it goes into the material (i.e., one vertically polarized ray of light, and one horizontally polarized ray of light), and the phase shift that happens to one of these polarized rays as they travel through the material, such that the two rays are now out of phase with respect to each other when they exit the material?
Or are you describing one ray of light, and are talking about the electric field and the magnetic field becoming out of phase with each other for that particular polarized ray of light? I've never seen this clarified by anybody. They simply talk about the "two components" of light, whatever that means.
Thanks for any input.
I talk about it a bit at 2:00, but the input light has equal E field components up and into the board. If we assume they are in phase (as drawn) then it is really light polarized at 45 degrees. I just drew it as two components to help visualize the two components separating. to be clear, all vectors shown are E fied, I don't draw B field vectors.
The word "unpolarized light" causes a lot of confusion. If you are working with idealized, monochromatic light like we do in an intro optics class, it can never really be unpolarized. There will always be a definite phase relationship between the two components. So it will be linear along a cartesian axis, linear long some other direction, circular, or elliptical. Truly unpolarized light has the E field vector direction randomly jumping the plane. But to get that it can't be perfectly monochromatic like in our drawings. I think I have a brief video or comment on this at some point, but it gets complicated so I never cover it in detail. "Coherence" is the topic to read about to learn more.
@@Prof-Hafner , Thank you for your response. I didn't see it before. Again, please forgive me, I'm not a physics students, but when you describe the "two components" in your answer, are you talking about the two components as being polarized and unpolarized light that have a phase relationship with each other, or are you describing something else?
Any time I have seen someone write or describe the "two components" of light, and a student asks them to clarify it, they clarify it by again talking about the "two components of light" and their phase relationship to each other. But they never explain further. I'm not a physics or engineering student, could you please explain the two components to me in a manner I can understand? Or are the two components of light simply polarized and unpolarized waves? Again, thank you for any clarification.
Summarized the topic in 6 minutes which I couldn't understand in 25 minutes lecture of my Professor.
I’m glad I could help!
Ok so that equation is describing the phase change is for inside the dielectric and not including what the wave experiences on the outside Kd(n2-n1)? Also when you mention the n-horizontal and n-vertical do you mean the ordinary and extraordinary refractive indecies for uniaxial crystals?
Outside both waves are going through vacuum (or air, same thing in this case) so their relative phase does not change. I probably needed to state that more clearly.
Yes, to second question.
@@Prof-Hafner Thanks for the explanation ive been struggling to set up the problems in optics because i didn't understnand how the phase changed
If birrefringence depends on polarization, why when a birrefringence material is beamed with natural light in the same direction of incidence, it always refracts the light in the same way ? Dont know if the question makes sense, but thank you anyway¡
I can't really do a detailed explanation in YT comment, but here is one thing to keep in mind as you contemplate these things: unpolarized light is not just a mixture of two linear polarizations. In that case it would just be 45 degrees linear. Or if there was a phase difference, some kind of elliptical light. Unpolarized light usually means incoherent light where the phase relationship between the two polarizations (x, y or horiz, vert) is randomly fluctuating. Or, you can just think of the electric field vector as randomly spinning around as it propagates. This leads to some differences of behavior than just thinking of unpolarized as a simple mixture. I'm not sure if it applies to what you are asking though.
both of you are wrong. the OP doesn't know enough to ask a cogent question and the responder failed to even try to decipher the gross concept errors.
@@h7opolo*coherent
Something your comment is not.
You get what you pay for
dropping hints on the sparkling pavement riddle . . . ?
You mean with this series on polarization? Then no, it is not that complicated! :)
Good sir
Sir why we use phase retarders?
They are mostly used in research where polarization states are used to study material properties. Phase retarders are used to manipulate the polarization before and after it interacts with a material. "Material" here can mean minerals, biological samples, bose-einstein condensates, etc!
@@Prof-Hafner thank you, now it's clear.
Sir I need further help regarding this topic, may I ask?
Still using a chalk board in this day and age?
I find that I can write and draw with much more detail with chalk than with a dry erase marker. Also, I haven't had any chalk "dry out" yet! :)