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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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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Why do optical-fiber based interferometers work?

Let's start with my basic understanding with interferometers (in general): a beam is split in two, travel in different arms, recombined coherently resulting in an interference (constructive, ...
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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 to simulate a Mach-Zehnder Unbalanced Interferometer with Single Photons?

I'm currently working on a project using a Mach-Zehnder Interferometer (MZI) with weak coherent pulses (single photons). In order to simulate the results I would like to use the Qutip library of ...
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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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Why is a Small Coherence Length Desired for Fiber Optic Gyroscopes?

For interferometric measurements based on the Sagnac effect, typically a light source is injected into counter-propagating paths of a fiber optic coil. The rotation of this coil of fiber optic cable ...
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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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Extreme sensitivity to the input scale of a Continuous Fourier Transform approximation from Discrete Fourier Transform

Is there a way to 'bypass' the condition $\Delta k=\frac{1}{x_{max}-x_{min}}$, which requires the range of $x$ to be very large when approximating the CFT encountered in Michealson Interometery as a ...
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Why is wavefront quality important, and what is the relationship between the coherence length of a laser and its wavefront quality (if any)?

I am currently studying laser interferometry. I understand that the coherence length of a laser, $L_\text{coherence} = c T_\text{coh}$, where $c$ is the speed of light and $T_\text{coh}$ is the ...
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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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Why is the sample interferogram given by the following integral of the intensity pattern?

I am trying to understand equation (2) in the paper by J. E. Greivenkamp with the title Generalized data reduction for heterodyne interferometry from year 1984. If you dont have acces to the article, ...
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Reduction Ratio in Michaelson Interferometer

I am trying to work out the relation between a $\mu$step and the distance moved by the moveable mirror in the Michaelson Interferometer: The mirror on the stage is moved by a stepper motor. Inside ...
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Is $I(\lambda)=I(\tilde{\nu})$ true in general in Fourier Optics?

Say the spectrum of a light bulb is given by $$I(\lambda)=I_0exp\left(-\frac{(\lambda-\lambda_0)^2}{2(\delta \lambda)^2}\right)$$ (i.e. a gaussian) if I want the intensity in terms of the wavenumber $\...
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Misconception with Fourier Transforms in a Gaussian Light source?

So for a Michaelson Interferometer , we know that the (complex) interferogram ($I=I(\Delta)$, $\Delta$=path difference between two mirrors) is related to the intensity profile of the light source $(...
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What is the difference between this "spectral width" and the laser linewidth (FWHM)?

I am currently looking at the 1550nm fibre-coupled DFB laser diodes on Alibaba for use in interferometry experiments. These are commonly used in optical communications applications, but it seems to me ...
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Why is the Pauli's exclusion principle not violated in the two neutron beams interference experiments?

It is my understanding so far that in this kind of experiments like the one measuring the 4π (i.e. 720° Dirac Belt trick) rotation characteristic of 1/2 spin fermions like neutrons, two neutron beams ...
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How can I simulate michelson's interferometer circular fringes?

I wanto to simulate the circular fringes on a screen for the michelson interferometer. I know how to identify if there will be a destructive or constructive interference, but what about the radius of ...
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Why do two-beam interferometers have a relatively broad "fringe width" compared to single-beam interferometers?

I recently overheard someone discussing the basics of interferometry setups. They said that two-beam interferometers have a relatively broad "fringe width" compared to single-beam ...
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Is it possible to use a distributed camera array to fake an interferometric sensor without phase data?

Astronomical interferometry is a technique which uses multiple small telescopes to mimic one giant telescope. It requires the phase of the light to be captured for it to work. It is widely used in ...
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Fabry-Pérot-Interferometer: What Reflectivity

Apologizing for that narrow question, but considering such interferometer with mirrors characterized by Reflectivity $R$ and reflection coefficients $r = \sqrt{R}$, where $R$ describes the amount of ...
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Why do the Fringes in Michelson Interferometer move inward/outward?

We did this experiment using Michelson Interferometer of monochromatic source $\lambda$ to find the refractive index $n$ of dry air in a chamber of length $L$ by counting the number of fringes moved ...
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Add coherence length factor in source term for light source

I am trying to model the behavior of a Michelson-interferometer driven by a light source with a short coherence length (i.e. some centimeters at max.). By placing transmittive material in one of the ...
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I polarize the slits (one H, the other V) of a Young's double-slit. If my source is H or V, do I see fringes? What about if my source is D or AD?

In my journey to understand light better, I build a "polarized Young's interferometer". Imagine the following polarizations: horizontal, vertical, diagonal, and anti-diagonal (H, V, D, and ...
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Is spatial coherence more important for interferometry, or is temporal coherence more important for interferometry?

I am currently going back through my textbook Laser Systems Engineering by Keith Kasunic. Chapter 1.2 Laser Engineering says the following: One of the primary goals of laser engineering is to meet ...
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Resolution of a Michelson Interferometer using a Webcam

I've built a Michelson interferometer which uses a webcam as screen. This setup shall measure and correct drifts in optical path difference of the two interferometer arms. I have problems determining ...

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