Rotating Polarization with Mirrors

Light and its behaviour and properties
Dinesh

Rotating Polarization with Mirrors

Post by Dinesh »

BobH wrote: I strongly disagree with this. Dinesh my friend, sometimes a mathematical analysis can go very wrong and this is one case if it led you to that conclusion. There is no way the polarization of the beam coming off the top mirror in the drawing referred to above is "horizontal" if the mirror itself is in the "vertical" direction with respect to the plane of incidence defined by the beamsplitter cube. No way. A page of argument won't change that, and only confuses anyone reading this topic.
Bob, I actually showed that it would be vertical. The reason is that the dipole moment of the atoms in the mirror are vertical and so the E vector is also vertical.

My point is not whether or not it's vertical, my point is: why? I repeat, in case it's been missed again: Why is it vertical? - there must be a reason besides, "Because I'm an 'expert' and I say it is". No one seems to be able to give a reason. If it's as "obvious" and as "simple", then surely it's not very difficult to explain why. Otherwise, I'm simply expected to understand this as a matter of faith or "belief", and I ain't too good in both the faith department and blind unquestioning belief in "experts" department. If I accepted faith and blind belief as criteria for understanding natural law, I'd have become a priest and not a physicist! (Not that I'm demeaning priests, I simply have a different weltanscauung) I need some sort of proof. If people simply accept facts and speculation on some sort of faith basis, how do you find anything new? With no clue about a reason for something, the phenomena is not understood, it's simply accepted. In such a situation (My gawd, I'm beginning to sound like Thomas Jannsen!) there can be no creativity because there's no understanding! As I've said many times, if gawd almighty told me it was vertical, I'd ask why and examine the proof. Kaveh flat out told me he couldn't tell me why
kaveh1000 wrote: I don't know how to answer your question.
So, why (besides the dipole moment argument). Does anyone have an alternate reason?

The point you make about the fact that the polarisation must be vertical because the mirror is "vertical" is presumably meant to mean that the mirror is tilted to the right of the beamsplitter and is presented with a horizontal polarisation (along the x in my coord system) that's in the direction of tilt. However, had it been presented with a horizontal polarisation along the z - the other horizontal polarisation - would the beam still be vertical? Since the beam is going "up", it can have two horizontal polarisations; if it had the other horizontal polarisation - the z direction in my system - the dipole moment would be along the z direction and so would the polarisation.
dannybee
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Rotating Polarization with Mirrors

Post by dannybee »

I think i agree with bob.. some time its just comsense ...and a good p-filter from a camera to use as a tool to check p rotation...when I do this in the lab I never think math but more simple sience and optics..and tweak it till it works :D beause which is better get a head hirting thinking math or just make it work for that set up...because i think it was dinesh that said it isnt the one with big labs and big phd's that make good holographer but one's who know how to make it work in the real world :D blood sweat and mirrors...hehehehe :P
Dinesh

Rotating Polarization with Mirrors

Post by Dinesh »

Ah, but there a lot of people who think that the Tupac hologram is a hologram. In fact, there's probably a 1000:1 ratio of those who think it's a hologram to those who know it isn't. By any definition of "common" sense, there are a 1000 "common"s to every "uncommon"! Presumably the argument that common sense wins out every time would indicate that the Tupac is now a hologram by "common" consent and sense?

However, if I say that the Tupac is a hologram and you say it isn't, surely we must actually show/demonstrate/prove/explain our reasons for our statement. If we simply yell at each other: "It is! It's obvious it is!" and "It isn't. Anyone can see it isn't!" (which is actually happening as I speak!) then all sense of rational debate and conversation has gone. All points are settled by a show of hands. All debates are decided by decibel and not reason. Now, both Musion and Tupac are holograms, Dihydrogen Oxide is one of the most dangerous materials on the face of the earth, there is a dinosaur in a lake in Scotland and aliens built the pyramids. All of these are "obvious" and "simple" to a lot of people. We've achieved the democratisation of the laws of physics!
Jem
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Rotating Polarization with Mirrors

Post by Jem »

BobH
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Rotating Polarization with Mirrors

Post by BobH »

Dinesh wrote:
BobH wrote: I strongly disagree with this. Dinesh my friend, sometimes a mathematical analysis can go very wrong and this is one case if it led you to that conclusion. There is no way the polarization of the beam coming off the top mirror in the drawing referred to above is "horizontal" if the mirror itself is in the "vertical" direction with respect to the plane of incidence defined by the beamsplitter cube. No way. A page of argument won't change that, and only confuses anyone reading this topic.
Bob, I actually showed that it would be vertical. The reason is that the dipole moment of the atoms in the mirror are vertical and so the E vector is also vertical.

My point is not whether or not it's vertical, my point is: why?
But you never mentioned that THAT was your point. It took ten posts after the glaringly incorrect statement I quoted before you argumentatively demonstrated yourself to be wrong, without explaining *why* you made the glaringly incorrect statement in the first place. So I have to ask, what was the purpose of the ten post argument, in which you were clearly incorrect? Why is it necessary to replace a physical explanation of a very simple arrangement of mirrors with a mathematical one, when a couple of simple sentences about relative planes of incidence would've done the job as well? If you're really looking for a reason why there's sometimes some backlash against what you post, here it is! And I say that with all my respect for a long time friend and fellow holographer. :|
Dinesh

Rotating Polarization with Mirrors

Post by Dinesh »

Bob, If you go back along this thread, you'll notice I've been asking why all along! Nobody seems to simply state why this polarisation is what it is. That's all I've ever wanted. everyone is so sure of themselves, but no one can apparently come up with a reason. Kaveh says it's "obvious" and "simple" but cannot explain why. You say you say you absolutely believe that kate's drawing is correct, again with no reason, John shows a picture of cube beamsplitters, but again with no reason. DJM I think came the closest, but I got thrown by the fact that he claimed that the p and s states were with respect to specific optics ("the mirror", the "cube" etc). However, I think that DJM actually came up with another reason (besides the dipole moment) in that Fresnel's equstions cannot be solved unless the beam is as Kate drew it. don't know if that's what DJM meant, but that;s what comes out if you read "between the lines" of DJM's explanation. You say
BobH wrote: Why is it necessary to replace a physical explanation of a very simple arrangement of mirrors with a mathematical one, when a couple of simple sentences about relative planes of incidence would've done the job as well?
But then, where are these simple sentences? People seem to get mad at me because I question? If my question is "obvious" and my mistake is "glaring", then where's the correct expalantion. No one has answered!

I hope I can put across some of my own feelings in this. You simply cannot state an fact and then state that it's "obvious" and simple" and "everyone knows it"! That goes against the grain of everything that any body of learning or study is based on. But, besides DJM, everyone is absolutely certain of this fact without knowing why???? Does no one actually care why something is what it is. Does everyone simply accept "experts" without question.

If you examine this series of conversations, you'll notice that I've been asking why all along! Does anyone (besides DJM's explanation of the Fresnel conditions and my explanation of the dipole moment) why? No one has posted anything about a simple explanation of the planes of incidence! I'm clearly wrong, but the answer to my mistake (or anyone's mistake) is not to bear down on the mistake and call the person who's made the mistake all kinds of fool and idiot, as you all have done, but explain slowly and carefully why I'm a fool and idiot. If I am a fool and an idiaot, then fair enough! I'll accept the name-calling and the anger. No one on this forum seems to care that insults have been thrown, names have been used insinuations have been made simply because I don;'t know why the polarisation is what it's claimed to be.

What a nice bunch we are!!!

I'm sorry. I really don't know why the polarisation is what Kate says it is. I finally figured out that it's the dipole moment. But I think that all this name calling, insinuations, anger and backlash are uncalled for!!!!

All of you seem to go into a rage because I'm actually excercising the physics degree that I earned at college. If my being a physicist bothers you all so much, perhaps I ought to redefine myself. I never took any courses in physics! I never stuidied any mathematics! There's actually no mathematics in holography. All facts are simply stated. I'm very very sorry that I actually implied that there is some physics and math in holography becauser I can clearly see my error. Ii now bow before you all in humble apology that I dared to invoke actual science and math. Please believe me that i will not post anything involving physics, math, chemistry or anything else of a scientific nature on these pages. Clearly anyone even claiming any scientific background to holography ought to be burned at the stake! I was going to say :

" I see three fingers" a la 1984, but that involves a knowledge of the Arts and Literature and I'm pretty sure you'll all get even madder at me if I invoke any form of erudition at all!!!!!




Dinesh wrote:
kaveh1000 wrote:Kate is right.
Why?

Since the output beam from the top mirror can be both horizontally and vertically polarised, what principle or law states which one it must be. There are three possibilities:
Both permitted choices occur, in which case, the bam is once more unpolarised
S polarisation is maintained, in which case it's horizontally polarised
P polarisation is created, in which case it's vertically polarised.
What law or equation determines which case occurs?
kaveh1000 wrote:Dinesh, I can only think you are trying to analyse the problem too deeply. I don't know how to answer your question.
kaveh1000 wrote:The portion of the beam reflected by the prism is s-polarized with respect to the prism face, but p with respect to the mirror.
Dinesh wrote: True. The polarisation is determined by the plane of incidence. The plane of incidence from the cube (prism) goes up and into the paper (my y-z plane) and so the beam is s, as you say. The plane of incidence of the reflected light from the upper mirror goes along the paper and so is p, as you say. But, that still doesn't explain why the output light is p and not s, which it can be. If it were s, then the beam would be horizontally polarised. My question: why isn't it s, since the input beam to the system is s?
kaveh1000 wrote:Dinesh, I can only think you are trying to analyse the problem too deeply. I don't know how to answer your question.
Dinesh

Rotating Polarization with Mirrors

Post by Dinesh »

Since I've been put down, demeaned and, despite several pleas for an explanation, ignored. Since I see no end to these repressive behaviours with no sight of any justice from anyone. I don't think that I can contribute anymore. If you all seem to think that I actually don't understand or know holography, and you all seem to think think there is no science in holography but simply hand waving statements and since no one seems to actually seek knowledge, just ego, I'd like to be taken off the membership rolls.

If any of you actually benefited from anything I wrote, I hope I taught or inspired you. I hope you carry forward the idea of rational discussion. I hope I left something of the excitement of new ideas and deep insight into these phenomena. Unfortunately, there are some here who's ego transcends any hope of insight or study. I'm clearly a fish out of water when I question, debate and try to inspire to some to greater heights.
BobH
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Rotating Polarization with Mirrors

Post by BobH »

Dinesh wrote: I'm clearly wrong, but the answer to my mistake (or anyone's mistake) is not to bear down on the mistake and call the person who's made the mistake all kinds of fool and idiot, as you all have done, but explain slowly and carefully why I'm a fool and idiot. If I am a fool and an idiaot, then fair enough! I'll accept the name-calling and the anger. No one on this forum seems to care that insults have been thrown, names have been used insinuations have been made simply because I don;'t know why the polarisation is what it's claimed to be.
I don't recall anyone calling you "all kinds of fool and idiot". Where's the insult and insinuations? I have to tell you the only insinuation I read in this thread is that you know what you're talking about because you're a physicist and everyone else here are "all kinds of fools and idiots" because of their inability to explain the most basic things about holography to your satisfaction and in the language of mathematics. :shock:

Why is it necessary (for example) for a photographer to know the physics of how light interacts with a reflective surface to explain how the mirror in their SLR camera works to someone new to photography? I only questioned the necessity of ten posts of argument about a statement you, the physicist amongst us, made about the polarization state of a beam in a specific drawing. The context of that statement doesn't imply to me that you were playing the "Devil's Advocate" when you made it, or that it was made to stimulate discussion about *why* light reflects off surfaces. :roll:
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Rotating Polarization with Mirrors

Post by dannybee »

BobH wrote:
Dinesh wrote: I'm clearly wrong, but the answer to my mistake (or anyone's mistake) is not to bear down on the mistake and call the person who's made the mistake all kinds of fool and idiot, as you all have done, but explain slowly and carefully why I'm a fool and idiot. If I am a fool and an idiaot, then fair enough! I'll accept the name-calling and the anger. No one on this forum seems to care that insults have been thrown, names have been used insinuations have been made simply because I don;'t know why the polarisation is what it's claimed to be.
I don't recall anyone calling you "all kinds of fool and idiot". Where's the insult and insinuations? I have to tell you the only insinuation I read in this thread is that you know what you're talking about because you're a physicist and everyone else here are "all kinds of fools and idiots" because of their inability to explain the most basic things about holography to your satisfaction and in the language of mathematics. :shock:

Why is it necessary (for example) for a photographer to know the physics of how light interacts with a reflective surface to explain how the mirror in their SLR camera works to someone new to photography? I only questioned the necessity of ten posts of argument about a statement you, the physicist amongst us, made about the polarization state of a beam in a specific drawing. The context of that statement doesn't imply to me that you were playing the "Devil's Advocate" when you made it, or that it was made to stimulate discussion about *why* light reflects off surfaces. :roll:
thanks Bob Dineash has left the forum :cry:
Last edited by Anonymous on Mon May 21, 2012 2:26 pm, edited 1 time in total.
dannybee
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Rotating Polarization with Mirrors

Post by dannybee »

dannybee wrote:
BobH wrote:
Dinesh wrote: I'm clearly wrong, but the answer to my mistake (or anyone's mistake) is not to bear down on the mistake and call the person who's made the mistake all kinds of fool and idiot, as you all have done, but explain slowly and carefully why I'm a fool and idiot. If I am a fool and an idiaot, then fair enough! I'll accept the name-calling and the anger. No one on this forum seems to care that insults have been thrown, names have been used insinuations have been made simply because I don;'t know why the polarisation is what it's claimed to be.
I don't recall anyone calling you "all kinds of fool and idiot". Where's the insult and insinuations? I have to tell you the only insinuation I read in this thread is that you know what you're talking about because you're a physicist and everyone else here are "all kinds of fools and idiots" because of their inability to explain the most basic things about holography to your satisfaction and in the language of mathematics. :shock:

Why is it necessary (for example) for a photographer to know the physics of how light interacts with a reflective surface to explain how the mirror in their SLR camera works to someone new to photography? I only questioned the necessity of ten posts of argument about a statement you, the physicist amongst us, made about the polarization state of a beam in a specific drawing. The context of that statement doesn't imply to me that you were playing the "Devil's Advocate" when you made it, or that it was made to stimulate discussion about *why* light reflects off surfaces. :roll:
Bob Dinesh has left the forum :cry:
Last edited by Anonymous on Mon May 21, 2012 2:31 pm, edited 1 time in total.
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