diffraction

Examples of diffraction in the following topics:

• Diffraction

  • Diffraction effects are generally most pronounced for waves whose wavelengths are roughly similar to the dimensions of the diffracting objects .
  • A good example would be diffraction gratings.
  • The effects of diffraction are often seen in everyday life.
  • The most striking examples of diffraction are those involving light.
  • Intensity pattern formed on a screen by diffraction from a square aperture.

• Diffraction Gratings: X-Ray, Grating, Reflection

  • Diffraction grating has periodic structure that splits and diffracts light into several beams travelling in different directions.
  • A diffraction grating is an optical component with a periodic structure that splits and diffracts light into several beams travelling in different directions.
  • Some bird feathers use natural diffraction grating which produce constructive interference, giving the feathers an iridescent effect.
  • An opal is another example of diffraction grating that reflects the light into different colors.
  • In an X-ray diffraction measurement, a crystal is mounted on a goniometer and gradually rotated while being bombarded with X-rays, producing a diffraction pattern of regularly spaced spots known as reflections (see ).

• Diffraction Revisited

  • De Broglie's hypothesis was that particles should show wave-like properties such as diffraction or interference.
  • X-ray diffraction is a commonly used tool in materials research.
  • Thanks to the wave-particle duality, matter wave diffraction can also be used for this purpose.
  • Working back from the observed diffraction pattern, it is then possible to deduce the structure of the crystal producing the diffraction pattern.
  • Compare application of X-ray, electron, and neutron diffraction for materials research

• X-Ray Diffraction

  • X-ray diffraction was discovered by Max von Laue, who won the Nobel Prize in physics in 1914 for his mathematical evaluation of observed x-ray diffraction patterns.
  • Diffraction is the irregularities caused when waves encounter an object.
  • In x-ray crystallography, the term for diffraction is Bragg diffraction, which is the scattering of waves from a crystalline structure.
  • n - numeric constant known as the order of the diffracted beam
  • Pulses of energy are plotted with respect to diffraction angle.

• Single Slit Diffraction

  • Diffraction is a phenomenon all wave types can experience.
  • In single slit diffraction, the diffraction pattern is determined by the wavelength and by the length of the slit.
  • From the center of the slit, the diffracting waves propagate radially.
  • Visualization of single slit diffraction when the slit is equal to one wavelength.
  • This figure shows single slit diffraction, but the slit is the length of 4 wavelengths.

• X-Ray Spectra: Origins, Diffraction by Crystals, and Importance

  • The process is called x-ray diffraction because it involves the diffraction and interference of x-rays to produce patterns that can be analyzed for information about the structures that scattered the x-rays.
  • This is called the Braggs diffraction, and is the basis for x-ray diffraction.
  • Using x-ray diffraction data, researchers were able to discern the structure of DNA shows a diffraction pattern produced by the scattering of x-rays from a crystal of protein.
  • X-ray diffraction from the crystal of a protein, hen egg lysozyme, produced this interference pattern.
  • Bragg's Law of diffraction: illustration of how x-rays interact with crystal lattice.

• Limits of Resolution and Circular Aperatures

  • In optical imaging, there is a fundamental limit to the resolution of any optical system that is due to diffraction.
  • As one decreases the size of the aperture in a lens, diffraction increases and the ring features from diffraction become more prominent.
  • Similarly, when imaged objects get smaller, features from diffraction begin to blur the boundary of the object.
  • Since effects of diffraction become most prominent for waves whose wavelength is roughly similar to the dimensions of the diffracting objects, the wavelength of the imaging beam sets a fundamental limit on the resolution of any optical system.
  • The observation of sub-wavelength structures with microscopes is difficult because of the Abbe diffraction limit.

• The Rayleigh Criterion

  • Along with the diffraction effects that we have discussed in previous atoms, diffraction also limits the detail that we can obtain in images. shows three different circumstances of resolution limits due to diffraction:
  • This is due to diffraction similar to that through a single slit.
  • Due to the diffraction, you can just barely distinguish between the two point sources.
  • (a) This is a graph of intensity of the diffraction pattern for a circular aperture.
  • (b) Two point objects produce overlapping diffraction patterns.

• Huygens' Principle

  • He could not, however, explain what is commonly known as diffraction effects.
  • Diffraction effects are the deviations from rectilinear propagation that occurs when light encounters edges, screens and apertures.
  • Figure 1 shows a simple example of the Huygens's Principle of diffraction.
  • We will examine in later atoms single slit diffraction and double slit diffraction, but for now it is just important that we understand the basic concept of diffraction.
  • As we explained in the previous paragraph, diffraction is defined as the bending of a wave around the edges of an opening or an obstacle.

• de Broglie and the Wave Nature of Matter

  • It took three years for Clinton Davisson and Lester Germer to observe diffraction patterns from electrons passing a crystalline metallic target (see ).
  • Before the acceptance of the de Broglie hypothesis, diffraction was a property thought to be exhibited by waves only.
  • Therefore, the presence of any diffraction effects by matter demonstrated the wave-like nature of matter.
  • Experiments with Fresnel diffraction and specular reflection of neutral atoms confirm the application to atoms of the de Broglie hypothesis.
  • In 1999, a research team in Vienna demonstrated diffraction for molecules as large as fullerenes.