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1d
revised Linear polarization measurement - what QM observable is measured?
included a line to make straightforward connection to a realistic experiment
2d
answered Linear polarization measurement - what QM observable is measured?
Nov
2
comment Two thin lenses in contact
I won't provide the answer but here are some hints: A convex lens is a converging lens. A lens $L1$ is more converging than another lens $L2$ if it converges the rays closer to the lens, i.e. $f_1 < f_2$ for their focal lengths. Rays emanating from infinity will converge on the focal point. But if these rays were already converging, then they will be focused closer to the lens.
Oct
29
comment Collinearity of two infrared (10.6um) beams
This product might be interesting.
Oct
28
awarded  Enthusiast
Oct
17
comment How can you determine the direction of the polarizing axis of a single polarizer?
Slightly pedantic but one could also use a pre-characterized light source which is linearly polarized in some intrinsic way. E.g., the laser gain in some anisotropic crystals can be polarization dependent.
Oct
16
revised Mirror that flips polarisation?
improved explanation and formatting
Oct
16
answered Mirror that flips polarisation?
Oct
12
revised What does $g^{(2)}$ signify in quantum optics? And how to calculate it?
corrected formula
Oct
11
comment Collinearity of two infrared (10.6um) beams
I would be inclined to say that the polarization may turn out to be okay if you use short fibers that are not subject to high environmental fluctuations, such as vibrations or temperature variations. Polarization controllers use birefringence and at least the basic principle should work. But it may require bending of the fiber which might add to your losses. So power budget might really be critical in the end.
Oct
11
revised What does $g^{(2)}$ signify in quantum optics? And how to calculate it?
added 130 characters in body
Oct
11
answered What does $g^{(2)}$ signify in quantum optics? And how to calculate it?
Oct
11
answered Collinearity of two infrared (10.6um) beams
Oct
9
awarded  Organizer
Oct
9
awarded  Commentator
Oct
7
comment What are the 'types' of parametric down conversion?
Good to know it helped. Perhaps you could mark this as an answer then?
Oct
6
answered What are the 'types' of parametric down conversion?
Oct
6
answered Why does Fermi level has a probability density of 1/2 while it may lie in the forbidden region?
Oct
6
comment Why does Dirac write $\langle\xi'|\overline{f(\xi)} = \overline f(\xi ')\langle\xi'|$?
I also agree with the answer of Nikos M. below. If you want to go further into deep & unchartered territories ;-), this link might be useful. As a gist, since $\xi$ is an observable, its eigenvalues $\xi^{'}$ must be real. In that case, its easy to see $\overline{f(\xi^{'})} = \overline{f}(\xi^{'})$
Sep
30
comment On solving a two lens system
Because the role played by the first lens together with the first (real) object has been completely taken into account. This one at a time procedure even holds for any complex optical assembly such as a cascade of $n$ lenses. The response of the $k^{th}$ lens in the cascade is influenced by lenses $1$ to $k-1$ but once we know this response, we can use that as an input to find the response of the $(k+1)^{th}$ lens while again ignoring all other lenses.