Questions tagged [interferometry]
Interferometry is the name for a class of measurement techniques based on the interference of coherent optical fields or other electromagnetic radiation. Generally, Interferometric measurements are extremely accurate, but can be difficult to perform. Common uses for interferometry are optical component metrology and stellar interferometry, although there are many applications.
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Significance of the eigenvectors and eigenvalues of an interferometer?
An interferometer acting on $N$ modes can be described in terms of an $N \times N$ unitary transformation $U$ acting on the creation or annihilation operators of the modes.
I'm wondering if there is ...
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Why does the placement of a lens effect the shape of the interference pattern in the Michaelson Interferometer?
Consider the simple Michaelson interferometer configuration below:
I'm working with this apparatus in lab, where we add an additional component (a bi-convex lens placed either between the light ...
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Measuring coherence length with the Michelson Interferometer
In lab, I've been asked to measure the coherence length of a green-light laser source using a Michelson Interferometer. To do so, I configure the interferometer such that a circular fringe pattern ...
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Phase estimation in contrast interferometry
In contrast interferometry, such as an atom interferometer using atoms in different momentum states or a fiber optic gyroscope (FOG), the signal in its simplest form can be written
$$S=\eta\left(1-\...
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How many fringes can pass by on a Michaelson interferometer?
A Michaelson interferometer is an instrument that most physics undergrads get to play with once or twice.
A beam splitter sends part of the light to each of two mirrors, the light returns, then hits ...
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The Dicke and Hopfield model of light-matter interaction
Considering the Hamiltonian below for the normal Dicke model below;
$$\hat H = {\omega _p}{\hat a^ + }\hat a + {\omega _m}{\hat b^ + }\hat b + g\left( {{{\hat a}^ + } + \hat a} \right)\left( {{{\hat b}...
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What is a 'good' coherence/correlation function for multimode spectra?
Following up on the question here and this answer in particular, I would like to pose the following question:
How to derive a formula for the coherence length of a multispectral source, such as a ...
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Magically reappearing fringes in Michelson interferometer for large path length differences?
I've built a simple Michelson interferometer from two mirrors and a beam splitter according to the following schematic:
Image source
My setup differs from the one in the publication in that mirror M1 ...
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Ramsey Interferometry in Three-Level Anharmonic System
Recently I've been studying the pulse-level control experiments available in Qiskit like the $T_2$ Ramsey experiments. I came across this page and was surprised to find that there are three- and even ...
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Why does the speed of Etherwind change? [closed]
I am currently reading texts on ether theory.
Now I have a question regarding the aether wind, since it is not well explained in the books I have read.
According to the theory, there must be a ...
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Mathematically, how exactly is $\langle \vert(E_m + E_r) \vert^2 \rangle$ calculated?
In a section on interferometry, my photonics textbook says the following:
Now, let's consider the signal obtained at the output of the interferometer. In general, the fields returned on the ...
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Interferometry maximum wavelength for a set of baseline lengths
I am trying to understand phase ambiguity resolution for interferometry. Unfortunately, all I have are old power points and not really any notes or textbooks on the subject.
I have found in a power ...
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How do you actually use an astronomical interferometer to measure small distances?
The question in the title might be too broad, so for definiteness we can focus on the Michelson stellar interferometer which, as I understand it, is more or less just two telescopes some distance ...
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Deriving the Interference Intensity of Michelson interferometer
I am trying to equate the equation i found wikipedia:
To the one given in my course notes which is:
Assuming a 50/50 beam split i have 1/2 where i should not have one:
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How does the interferogram in SD-OCT contain all the depth layer information?
I am reviewing Spectral-Domain Optical Coherence Tomography (SD-OCT) and I came across the figure which describes the principle of SD-OCT:
In Time-Domain OCT, the reference mirror has to move to ...
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What is the unbalanced Mach-Zehnder interferometer?
I read about unbalanced Mach-Zehnder interferometers in investigating the time-energy entanglement. I wanted to know what is it. and what is its purpose?
Thank you.
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Where Does Envelope Come From In Fourier Transform Spectrometers?
Here I a Michelson interferometer setup, with an interferogram output of a monochromatic light source (laser). As the translation stage moves, the interferogram amplitude is modulated with another ...
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Are human eyes interferometers?
It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
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Where does energy go?
Where does energy go?
Given is the Michelson interferometer. One sends light in
in the form of a plane wave $E_0\exp[i(kx-wt)]$ into the interferometer.
The position of one of the mirrors is adjusted ...
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Total Energy of an Asymetric 3x3 Coupler
In our experiments, we are using a 3×3 fibre couplers with light as part of an interferometer-setup. This coupler isn't symmetric; it's phase relation of every output is unequal to 120° and the ...
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Mach-Zehnder interferometer
I assume there are 2 kinds of Mach-Zehnder interferometers: real-world devices which detect for example impurities in gases and quantum devices used mainly in thought experiments, though I am sure ...
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Are all emitted photons accounted for at the detector(s) in the single-photon Mach-Zehnder interferometer?
Layman alert: I am sorry if I am asking stupid questions. I'm just trying to grasp what is happening with a single photon in MZ interferometer.
Say we have a single-photon source, and let the second ...
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Bohr interpretation of Mach-Zehnder interferometer
Consider MZI for single photon. Bohr or Copenhagen interpretation holds that the wave de Broglie attached to a particle is just amplitude(s) of probability (e.g. some information which is located (I ...
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In a Mirau Interferometer what is the distance between the mirror and the beamsplitter?
A Mirau interferometer (shown left in the figure, next to the Michelson configuration to the right) is an important instrument for non-contact surface profilometry.
Briefly, taken from Wikipedia, &...
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Single-photon Mach-Zehnder interferometer with complete destructive interference
This article describes an experiment where you can set up a Mach-Zehnder interferometer, and send one photon through at a time, and see complete destructive interference at one of the detectors (one ...
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Optical power between mirrors in resonant Fabry-Perot interferometer
I'm reading through the book Introduction To Laser Technology and just got to the section on Fabry-Perot interferometers. The book talks about the seemingly paradoxical behaviour of the optical power ...
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Question about Michelson Interferometer
In Michelson Interferometer, the mirror that lies in the middle (half-silvered mirror), can reflect and let through light. But the light after being reflected by the half-silvered mirror, only let ...
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Can photons get captured in a Fabry-Perot cavity, and if so, what happens when it's detuned?
I'm imagining a three-step experiment with a Fabry-Perot cavity, and I'm not sure what would happen at each step.
First, suppose there is input light exactly resonant with the cavity. If I turn off ...
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What is the path rays in Fabry–Pérot interferometer for calculation it resolution?
A Fabry-Perot interferometer shown in Figure below essentially consists of two parallel plates of glass whose inner surfaces are polished to a very high degree of flatness, and then coated with a ...
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Michelson interferometer with monochromatic light
I have a "simple" question: is it possible to see, in a Michelson interferometer, interference fringes with a monochromatic source of light? I have this doubt because I've seen that the ...
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Regarding two-particle interferometry and single-detector probabilities, Horne/Zeilinger (1989)
I was reading Horne, Shimony, Zeilinger "Two-Particle Interferometry" from 1989, an article showcasing how momentum-superpositioned particle pairs from a down-conversion crystal can lead to ...
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Optics - interferometers and interference
I was watching a video of Sabine Hossenfelder, in which interferometers were a topic of discussion. Excuse me if the answer is obvious because I am not a physics pro by any means, just an interested ...
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Reason why light beam hits detector
I was thinking about the basic structure of interferometers and I watched a video about it. I came across a simple illustration that looked something like this:
A laser beam is split into two ...
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Understanding Entanglement basis change in a practical sense
I am trying to understand the concept of basis change for a pair of entangled particles (in mathematical sense as well as what it means in case of detection on detectors in a Mach-Zehender ...
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In VLBI astronomy measurements, does one measure the same photon using both instruments?
Most professional astonomy (that I heard of) at visible or radio frequencies is done with instruments that try to collect EM waves such that signals stay coherent.
But I wonder why the light from ...
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Entangled particles in a Mach-Zehnder Interferometer [closed]
I am trying to understand the Mach-Zehnder Interferometer (MZI) in case of entanglement. Given a standard MZI with two beam splitters at each end and both paths of equal length. In case we send one ...
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Phase difference and path difference relation confusion
If two light waves of same wavelength reaches the point $ P$, then what is the relationship between path difference and phase difference? In many books I have seen that they assume two 1-D equation ...
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Spinor rotations - experimental confirmation [duplicate]
The map
$$ S \in SU(2) \to R(S) \in SO(3) $$
is two-to-one. A rotation $ R(2\pi) = 1 $ acting on vectors in 3-space is the image of two rotations $ S(0) = 1 $ and $ S(2\pi) = -1 $ acting on spinor-...
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What does quadrature mean in the context of sine waves and resonance?
I heard a professor talk about quadrature in a sine wave representing resonance in time. What is the quadrature of the wave, and what does it mean for a quadrature to shift?
To be more specific, a ...
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Why distance between source images in Michelson interferometer experiment is twice the distance between two mirrors
In the Michelson interferometer experiment, there are two mirrors which are perpendicular to each other. When we see in telescope, we see one mirror, let's name it (a), directly and one mirror as ...
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Orienting birefringent crystal the right way in an interferometer
I'm working in a lab that involves transforming the polarization state of one beam of light in an interferometer via a Barium Borate (BBO) birefringent crystal. As the polarization state is altered ...
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Calculating Coherence Length and spectral width given an interferogram
I'm currently doing a lab in which we use a Michelson-Morley interferometer to analyse different light source. One of the mirrors in the interferometer is moved by a stepper motor. One of the light ...
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How does two-wavelength interferometry mitigate vibrations in density measurements?
I am currently using interferometry to measure the density of a plasma. The interferograms are suffering from vibrations, and I know that two-wavelength interferometry may mitigate this. I am however ...
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Why does constructive interference occur at zero path difference in a Michelson interferometer?
I was reading Introductory Fourier Transform Spectroscopy by Robert Bell.
In chapter 9 "Beamsplitters" he states for self-supporting dielectric beamsplitters:
"There are $\pi$ phase ...
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How can two beams in the Michelson interferometer come back at the same time?
I am trying to understand this concept from my textbook.
According to the figure below, the time difference between the two paths $\Delta t=0$.
But why is this the case? Looking at the picture, the ...
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Michelson-Morley interferometer in free fall
We suppose that we have a Michelson-Morley interferometer in free fall, will there be no interference: the round trip time in both arms of the interferometer is the same?
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LIGO's upper-bound on the Michelson-Morley null result?
LIGO is essentially a Michelson-Morley experiment. What is its measured upper-bound on the fringe shift?
The most recent Michel-Morley experiment "Michelson–Morley experiment#Subsequent ...
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Small crack in bottom corner of a beam splitter
I'm working with a Sagnac interferometer. To split a laser beam (He-Ne), we are using a cubical, non-polarizing beam splitter from Thor Labs (BS031).
The beam splitter is fastened to a stand that is ...
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Phase shifts in different beam splitter designs
I am trying to understand how a Mach-Zehnder interferometer works. It seems that it will work whether we use two beam splitters that consist of either
glass prisms glued together
a sheet of glass ...
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Contraction in SR vs GR
I've always had a bit of fuzziness concerning relativistic contraction which I will try to put into words.
Iiuc in SR, moving objects contract in the direction of their travel, as measured by rulers ...
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