![]() Sometimes halos or rings can be seen around the Sun or the Moon. These points are not randomly distributed, but were formed by the diffraction pattern of the original object, which was illuminated with laser light and later engraved on a photographic plate. It is due to the superposition of the waves coming from the innumerable printed reflective points. The hologram that often appears on credit cards and branded products forms a three-dimensional image. They have their origin in the phenomenon of the diffraction of the light reflected by the sub-millimeter grooves that make up the tracks. The light bouncing off a CD or DVD also forms striking colorful patterns. They make up a very large set of secondary light sources, whose waves interfere, forming the colorful rainbow pattern that we admire so much after the rain. The rainbow is caused mainly by the superposition of the refracted and reflected waves inside the fine drops of water. Everyday examples of diffractionĭiffraction is a phenomenon that almost all of us surely observe, but we do not always properly identify its origin. This is how it is possible to show details that were previously masked in the originals, precisely due to light diffraction. Then, when processed computationally and extracting the noise from diffraction, they result in a higher resolution image. The technique consists of collecting a large number of images of the same object that individually are of low definition or brightness. Knowledge of the diffraction patterns present in photographic or digital images of astronomical objects: stars or asteroids, serves to improve the resolution of astronomical images. In this way, flaws or fractures can be detected in a part, which would hardly be visible to the naked eye. There a speckled diffraction pattern is produced ( speckle in English), which gives information on the surface from which the reflected photons come. When a surface is illuminated with laser light, the wavefronts of the light reflected from the surface are in phase, but they shift out of phase after traveling their way to the plate or screen on which the image is recorded. The speckle interferometry it is one of the practical applications of the phenomenon of light diffraction. It is produced by light from a laser pointer (wavelength 650nm) passing through a 0.1mm x 0.1mm square slot and projected onto a screen.Īpplications of light diffraction Detection of flaws or fractures in surfaces The figure above shows a very particular pattern of alternating light and dark areas. This is because the light beam is deflected and spreads around the edges of the obstacle. Rather, it diffuses around what should be its geometric shadow. When the object or slot that intercepts the light beam is on the order of tenths of a millimeter or less, the cast shadow is not accurate. It was the Italian Francesco Maria Grimaldi who gave the name of diffraction to this phenomenon and the first to study it in 1665. The diffraction of light is the name given to the distortion of a light beam when it hits a small object or a small opening in a screen. ![]() Detection of flaws or fractures in surfaces. ![]()
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