Interferometer Definition and 178 Threads

Interferometry is a technique in which waves are superimposed to cause the phenomenon of interference, which is used to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy (and its applications to chemistry), quantum mechanics, nuclear and particle physics, plasma physics, remote sensing, biomolecular interactions, surface profiling, microfluidics, mechanical stress/strain measurement, velocimetry, optometry, and making holograms.Interferometers are devices that extract information from interference. They are widely used in science and industry for the measurement of microscopic displacements, refractive index changes and surface irregularities. In the case with most interferometers, light from a single source is split into two beams that travel in different optical paths, which are then combined again to produce interference; two incoherent sources can also be made to interfere under some circumstances though. The resulting interference fringes give information about the difference in optical path lengths. In analytical science, interferometers are used to measure lengths and the shape of optical components with nanometer precision; they are the highest precision length measuring instruments in existence. In Fourier transform spectroscopy they are used to analyze light containing features of absorption or emission associated with a substance or mixture. An astronomical interferometer consists of two or more separate telescopes that combine their signals, offering a resolution equivalent to that of a telescope of diameter equal to the largest separation between its individual elements.

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  1. M

    Mach–Zehnder interferometer question, path detection

    In a Mach–Zehnder interferometer experiment, can you measure which path the beam took by measuring the change in momentum of the (fully silvered) mirrors (i.e. if path A was taken then the mirror on path A was "pushed" a bit, if path B was taken then the mirror on path B was "pushed" a bit)?
  2. D

    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...
  3. E

    Moving Interferometer: Exploring Photon Speed in Space

    If one makes a interferometer with a "arm" giant enough or moves it fast enough.. Forget that, basically you could have just a laser and detector floating in space, not connected, at huge distance, with the same speed and direction relative to a, say, planet in background. If the distance is...
  4. C

    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...
  5. S

    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.
  6. jk22

    Can one tell me if the treatment of the Mach-Zehnder interferometer in

    Can one tell me if the treatment of the Mach-Zehnder interferometer in the attachment is correct ?
  7. J

    What is the concept of total cancellation in a Michelson interferometer?

    SETUP: Michelson interferometer with laser source. d1, d2 are the beam to mirror path leg distances. Does anyone know how many times the light reaches the point total cancellation during a micrometer adjustment that passes from: d1 < d2 to d1 = d2 then d1 > d2 ? I know that some...
  8. C

    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...
  9. J

    Michaelson Interferometer and changing length of glass rod

    Homework Statement The index of refraction of a glass rod is 1.48 at T=20°C and varies linearly with temperature, with a coefficient of 2.5 E -5 °C-1. The coefficient of linear expansion of the glass is 5 E -6 °C-1. At 20.0°C the length of the rod is 3.00 cm. A Michelson interferometer has...
  10. Q

    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
  11. H

    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 +...
  12. R

    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...
  13. J

    Micrometer Attached to Movable Mirror in Interferometer

    Homework Statement A micrometer is connected to the movable mirror of an interferometer. When the micrometer bears on a thin metal foil, the net number of bright fringes that move, compared to the empty micrometer, is 272. What is the thickness of the foil? The wavelength of light used is 589...
  14. D

    Fabry Perot interferometer used as a filter

    Hi all! I'm studying Fabry Perot optical interferometer (with monochromatic light without taking time into account so far) and as its first application we studied it can be used as a filter, letting pass only certain frequencies \nu= \frac{mc}{2n_fd\cos(\theta_t)},\,\,m\in\mathcal{N} where c...
  15. A

    Advances in michelson morley interferometer

    hello, i am curious to know more about advancements that has happened to the M-m experiment, i am studying relativity and recently saw a http://youtu.be/7T0d7o8X2-E" of a modified interferometer. anyone knows a book/blog/file that talks purely about this. thanks.
  16. H

    Calculating Refractive Index Using Fabry-Perot Interferometer

    Homework Statement A Fabry-Perot interferometer has spacing d = 2 cm between the glass plates, causing the direct and doubly reflected beams to interfere. As air is pumped out of the gap between the plates, the beams go through 23 cycles of constructive-destructive-constructive interference...
  17. H

    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...
  18. zimo

    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...
  19. V

    Michelson's Interferometer Problem

    Homework Statement [PLAIN]http://img828.imageshack.us/img828/7386/physicsch3581.png Homework Equations Not sure The Attempt at a Solution the indicies of refracton are inversly related to the speeds, that is n=c/v . You find the time to go distance L in one arm t=L/v with air...
  20. Z

    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...
  21. Aaronvan

    NASA NASA cancels Laser Interferometer Space Antenna

    Bad news: http://blogs.discovermagazine.com/cosmicvariance/2011/04/06/nasa-gives-up-on-lisa/
  22. E

    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...
  23. M

    Resolution of a Michelson interferometer

    How to find the resolution of a Michelson interferometer ?
  24. G

    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
  25. T

    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...
  26. K

    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...
  27. J

    Aligning a Michelson interferometer

    Are there any tricks for getting the two arms of a Michelson interferometer exactly equal, if all I have is a CW HeNe laser to align? The real experiment will be using the interferometer on short pulses, so I will only see interference when the path lengths are equal to within 30 microns or so...
  28. A

    Michelson interferometer - maxima and minima

    URGENT! michelson interferometer - maxima and minima Homework Statement If a wave is reflected at a surface of a plate with higher refractive index (eg. At air glass or air-metal) it suffers a λ/2 phase change. Show that for the interferometer, maxima will occur for 2dcosθ = (n+1/2)λ and...
  29. W

    What happens to the missing intensity in a Mach-Zehnder interferometer?

    I am new to quantum physics and mostly self taught. Please forgive me for what is probably a very naïve question. Here's the way I understand it. A beam of photons is directed into a Mach-Zehnder interferometer (two beam splitters, two regular mirrors, and two detectors). At the first...
  30. R

    In michelson interferometer, does amplitude of of two waves is

    in michelson interferometer, does amplitude of of two waves is divided. i mean one wave say from fixed mirror has amplitue say A and the wave from moving mirror has amplitude say 0.8A? can we call this coherent source?
  31. C

    Interesting interferometer experiment

    I found this experiment on YouTube, and its about interference pattern variation in a vertically spinning interferometer.. http://www.youtube.com/watch?v=7T0d7o8X2-E&feature=related
  32. O

    Movable mirror of a Michelson interferometer

    i know the question may be a bit stupid to some people, but i seriously don't know how to do it... Homework Statement How far must the movable mirror of a Michelson interferometer, illuminated by a 589-nm source, be displaces for 2000 fringes to move past the reference point? Homework...
  33. H

    Interferometer / Index of Refraction

    Homework Statement Giancoli Ed. 6, Ch. 24, #52 One of the beams of an interferometer passes through a small glass container containing a cavity 1.3 cm deep. When a gas is allowed to slowly fill the container, a total of 236 dark fringes are counted to move past a reference line. The light...
  34. M

    What is the slope of the line between A and B on the uneven mirror's surface?

    Homework Statement Basically, there is an interferometer with one perfect mirror and a mirror with varying thickness across it. You shine parallel coherent light, wavelength 633nm, and see an interference pattern. The interference batter is wavy dark and light fringes of varying thickness. Two...
  35. S

    How Many Fringes Shift in a Michelson Interferometer When Air is Evacuated?

    Here's my problem: One of the arms of Michelson interferometer without the compensator consists of a cell 7.5 cm long. How many fringes would be observed shifting if all the air were evacuated from the cell? Use nvac= 1, nair= 1.00029 and the source wavelength 5,000 Angstoms (1 Angstrom =...
  36. N

    Deriving the Michelson Interferometer Equation: d_m = (m[lambda])/2

    does anyone know how to derive this equation regarding the Michelson interferometer: d_m = (m[lambda])/2 where d_m is the physical distance of a micrometer division, m is the number of fringes that crosses a screen given some d_m and lambda is the wavelength of the laser used to create the...
  37. N

    Tunable Fabry-Perot interferometer

    Hi all. I am trying to understand how a tunable Fabry-Perot interferometer works. This is what I have understood so far: An etalon is placed inside a pressure vessel, and the pressure inside this chamber is changed. Apparently, this changes the "effective optical path length" between the two...
  38. S

    Group delay measurement using Michelson Interferometer

    For my undergraduate project, I have been tasked to measure group delay of dielectric mirrors. I have found only papers that point mainly to use a Michelson interferometer using white light interferometry. I have googled and found how to construct a standard Michelson interferometer. However I...
  39. W

    So is there any other use to Young´s interferometer?

    Other than using it to prove the particle and wave naturo of particles and of course show interference? Or does it has some other use?
  40. E

    How Can Straight Line Fringes Be Observed in a Michelson Interferometer?

    Homework Statement Explain how a pattern of straight line fringes of equal thickness can be observed in a michelson interferometer. Homework Equations see diagram 1/3 of the way down page at http://www.holo.com/holo//book/book6&7.html The Attempt at a Solution I really am stuck...
  41. E

    Probability Density for Interferometer

    Hey guys. All of the info for the problem is in a picture (sorry for not using the template). I've tried working on this for ours and I still can't seem to get the trig identities right :( http://img208.imageshack.us/img208/1770/assignmentquestion2.jpg NOTE THAT THERE SHOULD BE ANOTHER...
  42. W

    Shear Interferometer to test collimation

    Hello everyone, I am trying to test the collimation of light emerging from an off-axis parabolic mirror. My mirror has a diameter of 0.5m or so. The focal length is about 5m. The light source I am using is a red laser focused at a pinhole. To test the collimation of this point source, I am...
  43. K

    Help me in michelson interferometer

    Homework Statement Find the angular radius of the tenth bright fringe in a Michelson interferometer when the central-path difference (2d) is (i) 1.50 mm and (ii) 1.5 cm. Assume the orange light of a krypton arc is used and that the interference is adjusted in each case so that the first...
  44. K

    Angular radius in michelson interferometer

    Homework Statement Find the angular radius of the tenth bright fringe in a Michelson interferometer when the central-path difference (2d) is (i) 1.50 mm and (ii) 1.5 cm. Assume the orange light of a krypton arc is used and that the interference is adjusted in each case so that the first...
  45. S

    Interferometer, Index of refraction of a gas

    Homework Statement One of the beams of an interferometer, as seen in the figure below, passes through a small glass container containing a cavity D = 1.34 cm deep. When a gas is allowed to slowly fill the container, a total of 222 dark fringes are counted to move past a reference line. The...
  46. K

    Interferometer Experiment: Rules for Adding Half Wavelength

    I am reading a scientific essay about a experiment with interferometer. They use so called 50/50 beam splitter and perfect reflector. Well they have the input wave be the plane wave exp(ikx), what interesting is: whenever the wave reflected by the splitter or perfect reflector, it add half of...
  47. C

    Simulating a Fabry Perot Interferometer

    I am making an attempt at simulating interference patterns of a Fabry Perot interferometer. I have fully derived the transmission function and the coefficient of finesse. T=\frac{I0 T^{2}}{(1-R)^2} + \frac{1}{1+FSin^2(\frac{\delta}{2})} Where F=\frac{4R}{(1-R)^2} and \delta =...
  48. J

    Michelson interferometer - change splitting pattern

    How would you change the splitting patterns for an interferometer? (Specifically a Michelson interferometer, if it matters) How would changing the fixed mirror, movable mirror, etc. affect the pattern? --- We just started learning some optics, and are just supposed to understand this...
  49. A

    Question concerning Michelson stellar interferometer

    Hello there, I have a question concerning Michelson stellar interferometer. It is about stars ejecting mass in a thin luminous shell of gas expanding to a size greater than that of star itself. So it says in the exercise: a michelson interferometer is used as a fourrier transform...
  50. J

    How Do You Solve These Michelson Interferometer Problems?

    Homework Statement 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 parallel-sided object...
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