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Why the total electric field amplitude change as mirror angle change? Polarization perspective

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Dear Zemax users,

I want to evaluate the polarization direction of a beam after some optical setup. What I usually did, is to quadratically sum (QSUM) the real and imaginary part of the Electric field from NSRA operand. Therefore I have Amplitude Ax, Ay and Az, which I simply take as the polarization direction.

As control, I evaluate as well the total amplitude by, again, quadratically sum Ax, Ay and Az; with the Power field of the source set to 1 Watt, it always sum to one (1) or less.

I assume, value less than 1 mean some of them are absorbed by the mirror etc since the reflectivity is less than 1. This assumption should be correct, shouldn't it?

However something bugs me now... In the attachment, I have set a Source Ray polarization to Jx = 1, Jy = 0. So it's linearly polarized. There are two mirrors, and I made two configurations with different angle placement of the mirror. After being reflected twice, I compare the result in the last segment.

As far as I understand, the end total amplitude value should be the same because the material and number of reflection is the same. However different angle gives different value (see Merit Function row 72). Can someone please elaborate?

Another question to confirm, if I put two segments after the chief ray before any reflection, the electric value part and its corresponding phase is changed. Since both total amplitude remains unchanged, I always assumed this is just because as a plane wave, the amplitude changes sinusoidally along the propagation axis. This assumption is correct isn't it?  (see Merit Function row 5-6 and 21-22)

Thank you for any help,
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Best answer by Widodo.Putro 7 November 2019, 08:58

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Just checking the theory behind it. Actually the absorption is also angle dependent.

So all clear