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Diffraction is the same physical effect as interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. [1]: 433 Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660.
In Young's experiment, the individual slits display a diffraction pattern on top of which is overlaid interference fringes from the two slits (Fig. 2). In contrast, the Lloyd's mirror experiment does not use slits and displays two-source interference without the complications of an overlaid single-slit diffraction pattern.
The Talbot effect is a diffraction effect first observed in 1836 by Henry Fox Talbot. [1] When a plane wave is incident upon a periodic diffraction grating, the image of the grating is repeated at regular distances away from the grating plane. The regular distance is called the Talbot length, and the repeated images are called self images or ...
Same double-slit assembly (0.7 mm between slits); in top image, one slit is closed. In the single-slit image, a diffraction pattern (the faint spots on either side of the main band) forms due to the nonzero width of the slit. This diffraction pattern is also seen in the double-slit image, but with many smaller interference fringes.
Figure 1. The light path through a Michelson interferometer.The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the ...
which is the generalized diffraction grating equation. Here, θ m is the angle of incidence, φ m is the angle of diffraction, λ is the wavelength, and m = 0, 1, 2... is the order of diffraction. Under certain conditions, d m ≪ λ, which can be readily obtained experimentally, the phase term becomes [7] [10]
The diffraction pattern of a beam of x-rays passing through a stationary crystal. The dots are areas of constructive interference; the crystal's atomic structure can be worked out from the pattern. In ptychography, a sample (which does not need to be crystalline) is moved sequentially through the beam, creating a range of diffraction patterns.
Duane showed that such a model gives the same scattering angles as the ones calculated via a wave diffraction model, see Bragg's Law. The key feature of Duane's hypothesis is that a simple quantum rule based on the lattice structure alone determines the quanta of momentum that can be exchanged between the crystal lattice and an incident particle.