Wavefront Definition and 36 Threads

In physics, the wavefront of a time-varying field is the set (locus) of all points where the wave has the same phase of the sinusoid. The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal frequency (otherwise the phase is not well defined).
Wavefronts usually move with time. For waves propagating in an unidimensional medium, the wavefronts are usually single points; they are curves in a two dimensional medium, and surfaces in a three-dimensional one.

For a sinusoidal plane wave, the wavefronts are planes perpendicular to the direction of propagation, that move in that direction together with the wave. For a sinusoidal spherical wave, the wavefronts are spherical surfaces that expand with it. If the speed of propagation is different at different points of a wavefront, the shape and/or orientation of the wavefronts may change by refraction. In particular, lenses can change the shape of optical wavefronts from planar to spherical, or vice versa.

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  1. S

    I Need to resort to spherical wavefront to derive the LTs?

    I have been reading Wikipedia’s derivations of the Lorentz Transformations. Many of them start with the equation of a spherical wavefront and this reasoning: - We are asked to imagine two events: light is emitted at 1 and absorbed somewhere else at 2. For a given reference frame, the distance...
  2. iVenky

    B How do you explain a plane wavefront based on huygens' principle?

    Let's assume a plane wave going in the x-direction. Going by Huygens' principle, each point on the wavefront should act like a source. If that's the case, wouldn't plane wavefront become spherical like shown below? I am so confused
  3. S

    I Young's double slit experiment -- Question about this wavefront diagram

    Hello, I have a question about the blue waves coming from sources S1 and S2 in de next picture. The blue waves from sources S1 and S2, are those two resulting waves (interference of all wavelets, Huygens Principle) or are those blue waves two wavelets?
  4. ItsKurious

    Interference of light by splitting the wavefront and recombining

    In the above diagram, I have illustrated what is written in the summery. So, if the thickness and refractive index of the material are chosen such that the part of the wave that travels through the slab acquires a path difference of λ/2 and at the right end if I keen another convex lens so as to...
  5. R

    Question about finding the amplitude of this circular wavefront

    I'm stumped. How do you get this without knowing the wavelength? Can someone explain how to get the answer?
  6. Bheshaj

    Wavefronts: Understanding Wave Optics

    What Is a wavefront? How can we interpret it?
  7. J

    Refraction of wavefront in water

    Homework Statement Homework EquationsThe Attempt at a Solution I think the water waves will undergo refraction from the interface and since it is denser , it should bend towards the normal . By that logic 4) should be correct , but this is incorrect . I might be applying wrong concept in...
  8. S

    How many places of maximum loudness?

    Homework Statement the last problem on this page: Homework Equations ##v= \lambda f## The Attempt at a Solution I'm guessing I'm looking for the maximum amplitude in a overlapping wavefront diagram like this? ## v=343m/s \\f=512Hz \\343/512=\lambda=0.67m \\3/0.67=4.5m ## So 4.5 wavelengths...
  9. C

    Orbital angular momentum wavefront velocity

    Is the wavefront velocity if an OAM mode 1 light beam proportional to its wavelength? I understand that the helical structure step length gives the wavelength of the beam. In this case, a small wavelength beam would travel much slower. The problem is, f=v/λ, but now v<c and if λ is shorter then...
  10. JulienB

    Fresnel zones of a planar wavefront

    Homework Statement Hi everybody! I'd like to ask you guys some details about the following problem: Determine the area of the l-th Fresnel zone of a planar wavefront considered from a point P. Give the numerical result for the 1st Fresnel zone for a wavelength ##\lambda=600##nm and a distance...
  11. P

    Lorentz Invariance of Plane Wavefront

    Homework Statement For a plane, monochromatic wave, define the width of a wavefront to be the distance between two points on a given wavefront at a given instant in time in some reference frame. Show that this width is the same in all frames using 4-vectors and in-variants. Homework...
  12. Ornit

    How to get to this Surface slope formula?

    This is no homework; but I cannot work it out so I assume one of my assumption is off... no matter how much I looked at it I can't get to the textbook answer. I tried searching (Google is my friend); I got to Prof. Burge's wonderful lectures slides (Arizona.edu) but he follows a different path...
  13. N

    Interpreting Seidel Aberration coefficients

    I am trying to model a simple system, but the ray-tracing does not seem to be consistent with the analysis of the system in terms of Seidel aberration values. Here's the system layout: When the system contains only the Eye model and the OL lens, it can be referred from the Seidel diagram that...
  14. gracy

    Huygen Wavefront: Drawing a Tangent to Wavelets

    One rule of huygen theory isfollowing The new wavefront is https://www.boundless.com/definition/tangent/ to the wavelets. If we look at reflection,to draw new wavefront we should draw tangent to the wavelets.should the two blue wavelets touch each other?Cannot we draw tangent to these blue...
  15. A

    Help Needed: Calculating Wavefront Error from PV Measurement

    Thank you all for any help or advice you can give. 1. Homework Statement What is the fabrication Wavefront error (WFE) of a mirror with a PV surface error of 1 um? Express your answer in terms of RMS waves at lambda = 0.633 um Homework Equations WFE=2*SFE The Attempt at a Solution I know...
  16. L

    Does a bullet have a wavefront stuck in its nose in vacuum?

    (like the wavefront that is photographed when it travels through air)
  17. AdityaDev

    Can a Convex Lens Converge a Tilted Wavefront?

    If I have a parallel beam of light parallel to x-axis, with the speed of light varying from bottom to top. Let it decrease from bottom to top. (To get such a beam one can pass the beam through a glass slab normal to its surface, whose refractive index increases linearly from bottom to top). Now...
  18. J

    What is the optimal format for posting physics problems on a forum?

    Homework Statement Attached file Homework Equations Attached file[/B]The Attempt at a Solution Attached fileSorry, I am in mobile, so i cant Write all the things,
  19. J

    Do I have the right understanding for a wavefront for sound and light?

    When a sound/light source propagates waves, do these waves travel radially(as in 360 degrees in the x y and z coordinate of space, like an electric field from a proton) around the source. For example, in the attachment I sent, is this a correct representation of a helicopter view of the waves...
  20. T

    What is a Wavefront? Understanding it

    I don't understand it.
  21. M

    Is the Universe an Expanding Wavefront?

    We all know that photons are the particle representation of an EM 2-D wavefront and as the front expands the space between photons increases. We also know that particles of matter can exhibit wave properties. So in an analogous fashion to light, I'm thinking that each of the fundamental...
  22. R

    Why is No Backward Wavefront Possible?

    Why no backward wavefront is possible?
  23. K

    How Do Infinite and Finite Light Sources Produce Different Wavefront Shapes?

    1.how and why does a light source in an isotropic medium at INFINITY produces PLANE Wavefronts instead of CIRCULAR Wavefronts as in case , when a light source is in the same isotropic medium but at FINITE distance? 2.how and why does a linear source of light such as a slit illuminated ...
  24. T

    Wavefront and point-like obstacle

    After reading about the diffraction and the multiple slits experiment, I've been wondering about what would happen if instead of slits, there were point-like obstacles (i.e., atoms). Using a plane wavefront and a finite number of obstacles, how would the light interact with this system?
  25. R

    Does a spherical wavefront thicken as it moves outwards ?

    If a flash of light is emitted spherically and this is measured in terms of its duration by two distant observers with one twice as far away from the source as the other, and the source and observers are all at rest with respect to each other, will the flash appear to have the same duration for...
  26. D

    Power of Wavefront Penetrating Dielectric Material

    Homework Statement How large proportion of wavefront's power penetrates dielectric material's surface in a perpendicular collision from air. The only parameter that I have is \varepsilon_r = 16 where \varepsilon_r is the relative permittivity.Homework Equations \varepsilon = \varepsilon_r...
  27. L

    Wavefront and wave - are they same?

    wavefront and wave -- are they same? Homework Statement Revered members, Are the terms wavefront and wave are similar? For example, in my attachment AC is incident wavefront. Perpendicular lines drawn from A and C, are incident waves. So those blue lines are mentioned as incident...
  28. P

    Calculate the angle between a refracted wavefront

    A wave is traveling from medium A to medium B. The ratio: r.i B / r.i A = 1.4. The angle between an incident wavefront and the normal to the boundary is 50 degrees. Calculate the angle between a refracted wavefront and the normal to the boundary: This is what I did: nAsin i = nB sin r sin...
  29. P

    Why is the wavefront error non-zero at the image plane in Zemax?

    Hi all I was searching the web to clarify a conceptual issue regarding the wavefront map in Zemax optical design software. Wavefront map in Zemax is suppose to tell us about the aberrations in the optical system. If I propagate a plane parallel beam in air from the object (at infinity) to...
  30. H

    Wavefront Simulation using Geometry Optics and Physical Optics

    I am required to simulate the propagation of a the wavefront produced by a laser light (about 633 nm) passing through a system of lens and undergoes a few reflection. What I did at the moment is to do ray tracing, record the optical path length of each ray, then connect every point of the same...
  31. I

    How does Wavefront technology used in optics work?

    Hi Everyone I'm new to PF, interestng reading, great site :o) I have a question relating to wavefront technology in optics. I visited my optician and they tried to sell me one of the new generation progressive lenses made as free form technology. Free form technology I understand...
  32. D

    How can I reproduce the wavefront interference photon detector seen on Nova?

    I am looking for someone that can tell me how to reproduce this experiment sen on nova last week A rectangular black box was used with a low power ? 1mw red laser . A long box was used there were 2 vertical openings left and right of the laser path to the photon detector. There was no direct...
  33. D

    Why Does Cylindrical Wave Amplitude Vary Inversely with Radius?

    does anyone know why, in order to conserve flux, the amplitude of a cylindrical wave varies inversely with its radius? I know the equation for a cylindrical wave is \frac{A}{\rho^{1/2}}e^{i(k\rho\pm\omega t)} , but how does this relate to conserving the flux? The main reason for my...
  34. M

    What is a wavefront? sine or cosine graph?

    What is a wavefront? Huygen's principle says that every point on a wavefront acts as a source of wave with the same speed. Now I am not asking you what that means, but i don't understand what a wavefront is. Is that like a circle? But wave is usually like a sine or cosine graph, so what's the...
  35. R

    Huygens' theory, point on a wavefront, secondary wavelets

    Huygens' theory says that every point on a wavefront serves as a source of secondary wavelet. Doesn't that imply that if we consider any coherent source of light, and intercept its waves on a screen, we'll get a diffraction pattern, as all those secondary wavelets will interfere among themselves?
  36. denian

    Cylindrical Wavefronts: Linear Source Intensity at 60m

    for a linear source in three dimensions, the wavefront are cylindrical. and intensity, I is inversely proportional to r ( distance from the source ) is the fact given correct?? here's the question. cylindrical wavefronts are emitted by a linear source of length 4.0 m, at a rate of 50...
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