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 classical field

I knew that $$I \propto |E|^2$$ I wanted to calculate intensity on detector 1 and detector 2 in Mach-Zehnder interferometer. One path have electric field $E_{1}$ and the second $E_{2}$. Its splits in ...
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Bragg and Raman beam splitters

In atom interferometry, what is the difference between Bragg and Raman beam splitter operations? When reading articles on atom interferometry I am finding statements such as `using a Raman/Bragg beam ...
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Why is it harder to use a white light source in a Michelson Interferometer?

In a Michelson Interferometer, a light beam is split into 2 different beams that travel different optical paths, through the "arms" of the interferometer. Then, they are reflected and, ...
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Cause of phase shift in matterwave interferometers

I am studying matterwave interferometry and I have read that the phase shift accumulated between the two arms of the interferometer is due to a coupling of the atoms to non-inertial forces. What is ...
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How is the phase gain of a Fabry-Perot resonator for gravitational wave detection derived?

I am trying to understand the use of the Fabry-Perot (FP) resonator in the arms of a gravitational wave detector. A typical explanation is that the gain in power in the arms is equal to $\sqrt{F}$ (...
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Infinite sum of transmitted parallel light fields

I'm currently studying optics and came across the possibility of retrieving the original electric (light field) from a pair of partially reflecting mirrors, but I am confused by several ...
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Particles in an interferometer in a gravitational field

Let's assume one has a standard interferometer, consisting of an incoming beam which gets splitted in beam I and II and then culminated again. Now the interferometer is placed in a gravitational field,...
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Time difference evaluation in a Michelson-Morley apparatus with arbitrary orientation

Historically, by assuming the validity of the Lorentz-Fitzgerald contraction, the null result obtained in the Michelson-Morley experiment can be explained. In particular light travels along the two ...
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Fringe movement analysis to extract displacement

I am using a Michelson interferometer with the interferogram recorded on a CMOS sensor. I have taken a video of the fringes moving when a displacement of 50 $\mu m$ is imposed to one of the mirrors. ...
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How does LIGO work?

LIGO is described as working as an interferometer, like a Michelson-Morley interferometer but with many reflections along the arms to increase the sensitivity. In MMs work it was assumed that the ...
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Derivation of the probability of joint detection in Hong-Ou-Mandel interferometer

I read the Hong, Ou, Mandel. "Measurement of Subpicosecond Time Intervals between Two Photons by Interference", from PRL 59, 2044. Where the - now known as - Hong-Ou-Mandel interferometer ...
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Spatial intensity distribution of a LED source

I hardly find instruments for applications like wavefront sensing of large optics (more than 200 mm diameter) using a LED source or halogen lamp. Is the maximum width limited by the low spatial ...
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Setting up Twyman-Green interferometer

I am trying to reproduce some experiments for multiple degree of freedom homodyne interferometry, but I am struggling to understand the basics of the hardware I need. The literature I am referring to ...
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Obtain clear fringes from interferometer

I have just begun setting up an interferometer to take some measurements. I am trying to reproduce one paper I found in literature for 3 DoF homodyne interferometry. The detector is merly a CMOS ...
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Circular fringes in Michelson interferometer

The rays reflected by mirrors M1 and M2 meet at the glass G. For each ray(specifically 1 and 2 in the figure which may go on 1,2,3... for an extended object as is required for the experiment) as the ...
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Quantum interferometer with floating mirrors [duplicate]

I send photons one at a time through a Mach–Zehnder interferometer with two detectors. Quantum superposition ensures that photons only reach one of the detectors. The interferometer is initially ...
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Tidal effect on interferometry

Interferometry relies on the change in the phase of two orthogonal light beams reflected back to the source point. Assume there is an interferometer at the equator, one mirror is planted 1 mile due ...
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Why do we use sodium light in Michelson interferometer for doublets?

I have a question regarding Michelson interferometer. I would like to know why we use sodium lamp for observing doublets instead of He-Ne laser or a regular lamp. Any help and explanation is much ...
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Heterodyne interferometry, an alternative?

I am trying to setup an interferometer to monitor displacements and tilts between two surfaces. I am quite struggling because I never studied optics deeply. I have found in this paper (https://...
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Laser interferometry for relative movements between two mirrors

I have been struggling in the past weeks to understand how should I setup a laser interferometer for my experiment. I am not a physicist, and I am quite new to optics. I have a Cassegrain telescope ...
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What does it mean for a light to have low-coherence?

I've been searching about OCT imaging and understood that it is based on low-coherence light source. The problem is, I don't understand what is a low-coherence light source. Based on what points that ...
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3rd Dimension on LIGO

The LIGO interferometers are 2 dimensional, they have $4\rm\ km$ legs that are perpendicular to each other. Could a 3rd $4\rm\ km$ leg either with a straight up tower or deep into the earth, provide ...
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Interference of Visible Light in Fiber Optics

I read this paper (the last sentence of Section 3.1). It is stated that in fiber optic interferometric sensors, the interference pattern cannot be detected if visible light is used because most fiber ...
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What happens when light of two different colours interfere destructively

In one of my lab courses, we are using an interferometer. I can understand how the interference works when it comes to monochromatic light, but for white light, I am unable to picture how the ...
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Michelson interferometer. Why is the path difference in the experimental setup $2d \cos \theta$ and not $2d/\cos \theta$?

All textbooks say that the path difference is $2d \cos \theta$. But in my mind, by constructing triangles, I seem to get $2d/\cos \theta$ and intuitively I thought as angle increases, the path ...
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Interferometry with photons in a mixed state: how to calculate the fringe visibility?

Suppose that Bob and Alice receive from John photons described by this density matrix: $\begin{bmatrix} 0.5 & 0.5 \ cos(\alpha) \\ 0.5 \ cos(\alpha) & 0.5 \end{bmatrix} $ They use these ...
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Non-quantum explanation for Mach-Zehnder interferometer effect

The phenomenon of all photons being detected at only one detector seems quite reasonable to me, classically. If a photon gets deflected at the first beam splitter for whatever reason, it gets ...
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Fabry Perot interferometer

I'm studying Fabry Perot Interferometer for the first time and I have some difficulties in understanding this model: there are two mirrors characterized by $r,t,T$ and between them there is a material ...
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Do we assume normal incidence for wedge fringes?

In wedge fringes we have fringes of equal thickness. Does this mean we only see equal thickness fringes when viewing very close to normal incidence, what are the fringes like for larger angles then?
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How are wedge fringes like Young's slits fringes?

It says in my optics lecture notes that by drawing virtual image point sources one can see that wedge fringes act like Young's double slit fringes. However, if this is the case, why do we observe ...
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Electromagnetic waves interference [closed]

Two charged bodies create a superposition of electrostatic fields at a point and there is no evidence of fields interference. Now, if we put two current circuits around the charged bodies then we ...
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How does a Michelson interferometer work?

First off, a Michelson interferometer does work. It can measure tiny length differences. Here is a video showing one in action. I must have misunderstood how it works. Here's what I think is happening:...
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Why Fizeau interferometers are much more popular than point diffraction interferometers for optical metrology?

If somebody wants to measure surface error of for example concave spherical surface - in most of the optical companies around the world Fizeau interferometer will be used, with relatively large, high-...
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How is VLBI delay calculated, practically?

I’m working on a research project wherein we are trying to solve a problem very similar to VLBI delay. We have two radio receivers, and we know their locations. We also know at what time one receiver ...
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How is interferometry used to measure distances?

I understand how a basic interferometer works, and how Michaelson used an interferometer to more-or-less disprove the “luminiferous anther”, but, analytically, how would one go about using an ...
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Etalon Produces Odd Interference Pattern

The other day I created an optical cavity with a first surface mirror and a beam splitter. Here’s a pic of the interference. Has anyone seen something like this. Is it common?
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Experiment involving a homemade Michelson stellar interferometer

I am in high school and for a research essay I am thinking of writing on the topic of Radio interferometry. My school has a Newtonian telescope and I was thinking of building a Michelson stellar ...
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Regarding Michelson's interferometer

In Michelson's Interferometer (1881 experiment), even though the arm length for both the perpendicular arms was taken as the same (say $L$) and a compensatory plate was used to removed optical path ...
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Phase unwrapping in interferometry

I observed that in "interferometry" is used a process called phase unwrapped. This process can be done by using complicated algorithms but I was not able to found an example more simplistic. If somone ...
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Fabry-Perot Interferometer

let's consider a Fabry-Perot interferometer: Illumination is provided by a diffuse source, and its rays are focused towards the cavity by a lens. Inside the cavity there are multiple reflections and ...
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Why is the central fringe in Fabry-Perot inteferometer dark?

We know that when the beams have phase shift due to reflection, the central fringe would be dark. But in the Fabry-Perot interferometer, except the first beam, each beam reflects 2 times (external ...
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Can someone help me understand this nested Mach-Zehnder interferometer by explicitly writing down the photon states in each steps?

The inner interferometer is balanced and it is tuned to destructive interference toward the final beam splitter of the external interferometer. The external interferometer has beam splitters with ...
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Does a Michelson pattern have a maximum radius?

I'm studying the Michelson interferometer interference pattern and we have arrived in class - using some aproximations - to some expressions which state a relationship between the radius of the ...
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Mach-Zehnder interferometer vs Michelson interferometer

I am doing a project that is based on the Mach-Zehnder interferometer, and we're asked to compare the interferometer with Michelson's interferometer. I know the geometrical differences between the two,...
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Difference between gravitational wave detectors

There are a lot of different gravitational wave detectors and they all have their own wave period and frequency they operate at. This picture shows that The last three (pulsar timing, space ...
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Does an interferometer add or multiply together signals? Is it either?

I'm studying honours physics right now and have to get an understanding of interferometers, specifically in the context of astronomy and interferometer telescope arrays. However, I'm having some ...
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Are the two interference patterns at the output of an interferometer quantum entangled?

When an interferometer creates an interference pattern a second interference pattern is always created. The two patterns are opposites of each other. Knowing one pattern lets me accurately predict the ...
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What should I look for when purchasing a Laser diode with good coherence?

I want to purchase laser diodes that will work well for interferometry. I have been using inexpensive laser diode modules that I buy from of Amazon for 2 or 3 dollars each. For the most part they ...
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On the optical equivalent of the Michelson interferometer

This page claims that the Michelson interferometer below is equivalent to the optical system bellow. How can it be? Where did the beam splitter go? And in the second system we restrict the incident ...
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Why do fringes appear, as opposed to a simple spot, in a Michelson interferometer?

A simple Michelson interferometer is generally presented like the one bellow If we observes through the telescope, we see fringes like these Is it the lens of the telescope that form theses fringes? ...

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