# What is Michelson interferometer: Definition and 73 Discussions

The Michelson interferometer is a common configuration for optical interferometry and was invented by Albert Abraham Michelson. Using a beam splitter, a light source is split into two arms. Each of those light beams is reflected back toward the beamsplitter which then combines their amplitudes using the superposition principle. The resulting interference pattern that is not directed back toward the source is typically directed to some type of photoelectric detector or camera. For different applications of the interferometer, the two light paths can be with different lengths or incorporate optical elements or even materials under test.
The Michelson interferometer (among other interferometer configurations) is employed in many scientific experiments and became well known for its use by Albert Michelson and Edward Morley in the famous Michelson–Morley experiment (1887) in a configuration which would have detected the earth's motion through the supposed luminiferous aether that most physicists at the time believed was the medium in which light waves propagated. The null result of that experiment essentially disproved the existence of such an aether, leading eventually to the special theory of relativity and the revolution in physics at the beginning of the twentieth century. In 2015, another application of the Michelson interferometer, LIGO, made the first direct observation of gravitational waves. That observation confirmed an important prediction of general relativity, validating the theory's prediction of space-time distortion in the context of large scale cosmic events (known as strong field tests).

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1. ### Calculating the Period of Fringe Pattern for Michelson Interferometer

In a Michelson Interferometer when Mirror 1 is moved a distance Δ𝑑=𝜆0/2Δ, this path difference changes by 𝜆0, and each fringe moves to the position previously occupied by an adjacent fringe. Δ𝑑=𝑚(𝜆0/2) I also know from the equation for I0=2I0 - 2I0 cos (2kdL or 2wt) that the fringes shift by a...
2. ### B How are 'fringe shifts' in the Michelson-Morley experiment calculated?

Ok for the interferometer let the arm lengths be ##L##, speed of light relative to the aether be ##c## and the speed of the setup relative to the aether be ##v##. By calculation you can show that the distance between the two 'heads' of the beams of light is ##\frac{v^2L}{c^2}##, and using the...
3. ### Converting Voltage into Pressure

I am measuring the index of refraction of air using a Michelson interferometer. This set up includes a gas chamber that is placed on of the paths of source laser after it passes through a beam splitter. The gas chamber is pumped to vacuum, and then air is allowed to slowly enter the gas...
4. ### I Why do we always see interference pattern in Michelson interferometer?

In a Michelson interferometer with a monochromatic laser, why do we always see an interference pattern even if we move one of the mirrors? Shouldn't it be a certain distance for which the movable mirror reflects the wave to be in opposite phase with the other wave so that they interfere...
5. ### I Find the interference function for different emission modes

Homework Statement:: Find the interference function ##I(\delta)## where The emission is analyze by a Michelson interferometer. Relevant Equations:: ##I(\delta) = \frac{1}{2} \int_{-\infty}^{\infty} G(k) r^{ik \delta} dk## ##I(\vec{r}) = I_1 + I_i + 2 \sqrt(I_1 I_i) cos (k\delta)## I have 5...
6. ### Michelson Interferometer with a lens

Hello everyone, i have a homework but I'm so confused how to solved it , can someone make a solution manual for this homework?, Thankyou.
7. ### I Correct Formula for "No Fringe Condition" (Michelson Interferometer)

In two different textbooks, there are two different formulas with different derivation styles for the "No Fringe Formation" Condition. In approach (a), they use an amalgamation of bright and dark for 2 wavelengths having very minute difference in the following manner: 2dcostheta=n*λ(1)...
8. ### Michelson interferometer -- Plotting experimental data to determine t

See attached images.
9. ### I What causes the Sagnac effect?

Wikipedia explains the Sagnac effect as a result of the rotating disk, which moves the target so that one of the light beams has farther to travel and consequently, will arrive later than the other light beam which goes around the disc in the same angular direction as the rotating disc. However...
10. ### B Beamsplitter in a Michelson interferometer

For a science fair experiment at high school I built a Michelson interferometer that could achieve a single interference state. Now there are two beams exit from such an interferometer, if a dielectric beamsplitter/combiner is used, one beam exits in a constructive state, and the other in a...
11. ### I Michelson interferometer dimensions

hi i want to design michelson interferometer device for measuring small distance movement i am using laser diode with a wavelength 635 nm and power 3 mw can anyone tell me how can i decide the dimensions (from source to beam splitter , for beam splitter to fixed mirror , from beam splitter to...
12. ### I have problem with a mirror on Michelson interferometer

My students and I tried to create a Michelson inerferometer like yours (08557.00). The problem is with a mirror that moves. How did you solve this precise translatory movement? Professor of Physics Nikola Gledić - Technical school Šabac, Serbia Thanks in advantage!
13. ### I Amplitudes in a Michelson interferometer

Hello, I am having a hard time understanding a result relating to a michelson interferometer. I always assumed that when the beam hits the wave splitter both resulting waves will have half the amplitude of the original wave. However using this assumption does not give the correct irradiance for...
14. ### Fringe Visibility of Sodium Doublet in Michelson interferometer

Homework Statement The sodium D-lines are a pair of narrow, closely spaced, approximately equal intensity spectral lines with a mean wavelength of approximately 589 nm. A Michelson interferometer is set up to study the D-lines from a sodium lamp. High contrast fringes are seen for zero...
15. ### Fringe-Shift in Michelson Interferometer with a Moving Source

Homework Statement The Michelson interferometer in the figure below can be used to study properties of light emitted by distant sources A source ##S_1##, when at rest, is known to emit light at wavelength ##632.8~ \rm nm##. In this case, if the movable mirror is translated through a...
16. T

### Transmission and reflectivity in a Michelson interferometer.

Homework Statement Sketch and explain the operation of the Michelson interferometer. How is the transmission of the interferometer modified if the amplitude transmission t and reflectivity r of the partially-reflecting beamsplitter are not equal? What happens to the fraction of light that is...
17. ### Using multiple mirrors in Michelson Interferometer

The number of mirrors typically used in Michelson Interferometer is 2. I am looking up the respective Wikipedia article and MIT's youtube video. I am wondering, for the sake of one of my experiment, whether more than 2 mirrors can be used in the interferometer? I require the traversing mirror...
18. ### Special Relativity: Rotated Michelson Interferometer

Homework Statement The aether-wind theory of the Michelson-Morley experiment was discussed in class for the special case where the arms of the interferometer (each of equal length L) are parallel and perpendicular to the wind. In this problem we consider the general case for an angular setting...
19. ### Michelson interferometer moves and bright fringes disappear

Homework Statement In a Michelson interferometer, as one of the mirrors is moved, 250 bright fringes disappear into the centre. If the light wavelength was 800nm, how far was the mirror moved? Homework EquationsThe Attempt at a Solution My logic is: If we were to count how many passing bright...
20. ### Michelson Interferometer IR Lab Question

I've been reading up on Fourier Transform Infrared Spectroscopy and the Michelson Interferometer. My main sources are "Principles of Instrumental Analysis" by Skoog etc and Fourier - Transform Infrared Spectrometry by Griffiths and Haseth. I believe I understand the theoretical principles...
21. ### How Does a Michelson Interferometer Measure the Thickness of a Piece of Plastic?

I'm reading about an experiment done with a Michelson interferometer. The aim is to measure the thickness of a piece of plastic. They use white light, so the central fringe in the interference pattern, corresponding to equal path lengths in the two beams can be used as a reference. Why does that...
22. ### Optics: Center of Fizeau Fringe? Michelson Interferometer

Hello everyone, i am simulating a Michelson interferometer, where one mirror is slightly tilted, see picture.. This results in circular arcs / hyperbolic cross-section fringes. The center of these fringes depends on the focal length i am using, see picture. Is there an analytical expression for...
23. ### Michelson Interferometer ring contraction

I have been trying for hours to understand what is physically causing the interferometric rings to contract when the separation of the mirrors is reduced. From the equation: m\lambda = 2Lcos\theta, where m is the number of fringes, if we consider just one fringe at a fixed wavelength...
24. ### Michelson Interferometer (Zero Path Difference)

Homework Statement A Michelson interferometer is illuminated with a laser with a wavelength of 514.5nm. A Haidinger fringe pattern is photographed with a lens of focal length 55mm. The diameter of the two adjacent circular fringes in the image are 1.53mm and 2.62mm. How far would the mirror...
25. ### How Does a Michelson Interferometer Measure Distances?

Homework Statement My personal question: What does a Michelson interferometer tell us? The actual problem: A Michelson interferometer is used to precisely measure distances of the order of 1 mm using a laser of wavelength 632.8 nm. a) If the motion of one mirror is 1 mm, what is the...
26. ### Michelson Interferometer - calculating errors

Homework Statement Part (a): Find an expression for intensity, interference phase and total change of interference phase. Part (b): Find an expression for <L1>/L0 and its error. Part (c): Find an expression for Δø1 and proportionality constant. Part (d): Find an expression for n(0) and α...
27. ### Michelson interferometer fringes

Since 2 splitted beams meet at ONE spot later on, we have just one beam which flows to the detector, therefore I expect to see just one light spot, where the BRIGHTNESS is changing depending on at which phase 2 beams meet. Pattern with fringes happens when we have multiple sources, like Young's...
28. ### Michelson Interferometer: Optics

Homework Statement A Michelson Interferometer has incident light in range 780-920 nm from a source. Intensity as a function of x (distance from central maxima) is given by: I_{(x)} = 3I_0 + 3I_0 cos(K_1x) cos (K_2x) - I_0 sin (K_1x) sin (K_2x) where ##K_1 = 1.3 x 10^7 m^{-1}## and ##K_2 =...
29. ### Need some help trying to understand the Michelson interferometer

Refer to the second diagram on this website http://electron6.phys.utk.edu/optics421/modules/m5/Interferometers.htm Using monochromatic light at first, you produce an interference pattern using the Michelson interferometer. If you set the relative tilt of the mirrors so that they are...
30. ### Michelson interferometer average power derivation

Homework Statement Using the trig product identity, cosαcosβ=\frac{1}{2}[cos(α+β)+cos(α-β)], show that the time-average power at the detector can be written as Pavg = 1+cos(δ) That = is supposed to be a proportional symbol. Homework Equations Other than the ones given in the problem...
31. ### Why can't I see fringes with eyepiece in my Michelson Interferometer?

Hello Forum I have constructing a Michelson Interferometer using sodium light. For viewing the fringes, I have used spectrometer telescope with objective lens of 178mm focal length, 35mm dia and eyepiece 15X. I can see the localized fringes when I view through the objective glass but without...
32. ### Solving for Mirror Displacement in a Michelson Interferometer

Homework Statement The distance between the movable mirror and the beam splitter in a Michelson interferometer is increased a small amount. When this happens, you see 200 dark fringes move across the field of view. If the incident light was 600nm, by how much was the mirror moved (in...
33. ### Why is the equation for delta t in a Michelson interferometer 2(L/v - L/c)?

Homework Statement In one arm of a Michelson interferometer the light passes through a glass tube of length L which contains air. The air is pumped slowly out of the tube and during this process it is found that the intensity of light reaching the eye has increased and decreased n times...
34. ### Why do Michelson interferometer usually needs 2 mirrors?

I've been wondering this for quite some time. Why do a typical set-up of Michelson interferometer usually requires 2 mirrors? Why not one for adjustment? Why not just shine the laser through the beam splitter? Thanks.
35. ### Exploring Interference Patterns: Building and Testing a Michelson Interferometer

I would like an outside opinion on something I've been thinking about lately. If one of the outer mirrors on a Michelson interferometer was to be misaligned by a small angle of theta, what would be the shape of the interference pattern in the detector plane? What would happen to this pattern as...
36. ### Michelson Interferometer and mirror

Consider a Michelson interferometer with semi-transparent mirror with a reflection coefficient for the intensity, R and transmission of T=1-R. The mirror does not absorb anything. Calculate the intensities of the light in the two outputs as a function of delta_x = x_2-x_1 which is the...
37. ### PGRE | Michelson Interferometer Equation

Homework Statement I am having trouble understanding how I would apply the Michelson Interferometer equation to a problem on the PGRE. Here is a link to a diagram displaying the interferometer as well as the equation which is very similar to the way the topic is shown in my REA pgre book...
38. ### Why are Localized Fringes Curved in a Michelson Interferometer Experiment?

hi everyone, can anyone explain why localised fringes are curved in michelson interferometer experiment with a monochromatic light used, when the mirrors are held not exactly perpendicular to each other and there is wedge formation.
39. ### Michelson Interferometer - Fringe Shape

Hi all Edit: The reflecting side is the right side of left slab Please look at the pic above ... The light from source splits at left slab and goes in 2 directions and come back to interfere. From figure, it is obvious that path diff. in slabs for both rays is 0 and only path diff...
40. ### What is the speed of light in a Michelson interferometer?

can someone explain to me the speed of light to the mirror and back from the mirror before reaching the telescope ?? please
41. ### Help Deriving Intensity Equation for Optical Michelson Interferometer

Homework Statement I am currently studying the optical Michelson Interferometer and I am in need of help with a derivation. The equation I need to derive is that for the intensity of the light arriving at the viewing point. The equation is given below.Homework Equations I(Δ)=I/2 +...
42. ### Michelson Interferometer homework

Homework Statement 1. A Michelson interferometer is operated in a vacuum, using monochromatic light of wavelength 589 nm. The interferometer is set up so that the distances between the moving mirror and the beam splitter and the fixed mirror and the beam splitter are equal. A...
43. ### Measure the length of a material with Michelson interferometer

Homework Statement Suppose you know the wavelength of light passing through a Michelson interferometer with high accuracy. Describe how you could use the interferometer to measure the length of a small piece of material. 2. The attempt at a solution - Sandwich the piece of material behind...
44. ### Michelson Interferometer question

Homework Statement Express the intensity from a beam that crosses a Michelson Interferometer that its beam splitter transfers 1/3 and reflects 2/3. Homework Equations N/A The Attempt at a Solution Would like to have a hint...
45. ### Cause of interference pattern in the Michelson Interferometer.

The books say that interference happens basically between the light waves from the two mirrors. But it seems to me that the path difference between the pairs remains constant for all the waves (as long as both the mirrors are perpendicular to each other). So why do circular rings form? How does...
46. ### Double-Slit Experiment and Michelson Interferometer

If, in the double-slit experiment, individual photons only interfere with themselves, as apparently happens when the stream of photons is slowed down to "one at a time", does the same rule or phenomenon apply to the various Michelson interferometer experiments? I think it was in Dirac’s...
47. ### Resolution of a Michelson interferometer

How to find the resolution of a Michelson interferometer ?
48. ### Michelson Interferometer, circle fringes

Hello guys! Lets say we have a laser beam and we send it to a michelson interferometer. Why the beam pattern at the screen gives circles and not lines or something else? Thanks P.S. see for instance http://techtv.mit.edu/collections/physicsdemos/videos/9823-michelson-interferometer
49. ### Michelson Interferometer, Optics Derivation

Homework Statement Derive the exact expression for the index of refraction n of a glass plate as a function of the fringe shift m, the plate thickness t and the angle of deflection of the plate (hint: find the optical path difference for an incident vs a tilted incident beam, and solve for...
50. ### Michelson interferometer and Doppler effect

Homework Statement Hello, I'm working on an experiment that involves a Michelson interferometer and doppler effect. Here is the description of the apparatus. Michelson interferometer is set up with one moving arm and microwave is transmitted and received. With the beam splitter splitting...