Diffraction Definition and 1000 Threads

Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660.

In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic bending pattern is most pronounced when a wave from a coherent source (such as a laser) encounters a slit/aperture that is comparable in size to its wavelength, as shown in the inserted image. This is due to the addition, or interference, of different points on the wavefront (or, equivalently, each wavelet) that travel by paths of different lengths to the registering surface. However, if there are multiple, closely spaced openings, a complex pattern of varying intensity can result.
These effects also occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance – all waves diffract, including gravitational waves, water waves, and other electromagnetic waves such as X-rays and radio waves. Furthermore, quantum mechanics also demonstrates that matter possesses wave-like properties, and hence, undergoes diffraction (which is measurable at subatomic to molecular levels).

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  1. M

    D spacing from X-ray diffraction data

    How do get the d spacing from XRD data, using braggs law. I am unsure how to actually obtain the value of d. I have attached the file as a text file with the data in. Many thanks for the help.
  2. I

    How does the placement of a lens behind a slit affect the diffraction pattern?

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  3. K

    Quasicrystal diffraction pattern

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  4. J

    Beautiful Natural Oceanic Diffraction Patterns

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  5. P

    Total phase difference diffraction help

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  6. K

    Deriving F=a2/λL in Fresnel Diffraction

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  7. J

    Maximum Intensity Between Dark Fringes, Diffraction

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  8. J

    Physics - Single Slit Diffraction

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  9. D

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  10. C

    Number of interference fringes visible in the central diffraction peak

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  11. 0

    Need simulate program for fresnel biprism diffraction

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  12. C

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  13. M

    Chiral nematic liquid crystals - describing light diffraction

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  14. S

    Exploring 2D Diffraction Spacing and Light Transmittance in 40um x 40um Lattice

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  15. R

    Understanding the Absence of [001] Diffraction Peak in X-Ray Diffraction

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  16. M

    Diffraction of Sound: Exploring Why Wavelength Matters

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  17. G

    Diffraction grating spectrometer

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  18. G

    Double-slit diffraction with thin film interference

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  19. mishima

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  20. A

    Diffraction Grating Overlapping Orders

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  21. C

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  22. K

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  23. U

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  24. V

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  25. C

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  26. T

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  27. B

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  28. P

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  29. P

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  30. bearcharge

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  31. bearcharge

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  32. L

    Why is there a spectrum on the back of a CD or DVD?

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  33. fluidistic

    Physical meaning of a result in Bragg's diffraction

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  34. M

    Understanding Light diffraction

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  35. P

    Single Slit Diffraction find central maximum

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  36. C

    Diffraction grating angular separation

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  37. P

    Diffraction from Sub-Wavelength Features

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  38. P

    Why Do Some Diffraction Orders Go Missing?

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  39. S

    Calculating Diffraction Intensities

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  40. R

    Diffraction Patterns: Calculate Wavelength of Light

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  41. P

    What is the relationship between diffraction and resolving power?

    Hi, Going through a Physics problem in class today my teacher stated that we could only resolve if: θ = λ/b. Why? Is it because when that does not follow, there is no "black spot", therefore that light source can merge with another one? Thanks, Peter
  42. P

    Diffraction and Semi-Conductor Lithography

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  43. P

    Diffraction and Aperture Size: How Does It Affect Image Resolution?

    Hi there, I understand somewhat how diffraction works in terms of the aperture of a camera lens and the resulting loss in resolution in the image, but my question is: Is the degree of diffraction only dependent upon absolute aperture size, or the size of the entrance pupil? For example, f/22...
  44. N

    Diffraction grating & young double slit -light not perpendicular to grating

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  45. H

    Alternating violet and red fringes in Diffraction Grating

    When white light is passed through the slits in the grate and hits a screen some distance away from the grate, different order spectra appear. My textbook tells me that violet light is always closer to the zeroth order bright fringe than red light because it has a shorter wavelength. However...
  46. I

    Help me understand interference and diffraction better

    Homework Statement I've been reading a book about waves. I skipped the test earlier this year because I had not done any problems and thought it would be a waste of time to try. But now I kind of have to do it, I've re-read the book but it's much to understand and remember. Especially the...
  47. N

    Diffraction - Why must slit width be comparable to the wavelength of light?

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  48. M

    Question about electron diffraction

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  49. khurram usman

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  50. S

    How/why does diffraction occur?

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