The periodic arrays of submicrometre spherical particles provide similar arrays of interstitial voids, which act as a natural diffraction grating for visible light waves, particularly when the interstitial spacing is of the same order of magnitude as the incident lightwave.

This is due to the superposition, or interference, of different parts of a wave that traveled to the observer by different paths ( see diffraction grating ).

The most striking examples of diffraction are those involving light ; for example, the closely spaced tracks on a CD or DVD act as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.

This principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired ; the hologram on a credit card is an example.

James Gregory ( 1638 – 1675 ) observed the diffraction patterns caused by a bird feather, which was effectively the first diffraction grating to be discovered.

Diffraction of a red laser using a diffraction grating

A diffraction grating is an optical component with a regular pattern.

The light diffracted by a grating is found by summing the light diffracted from each of the elements, and is essentially a convolution of diffraction and interference patterns.

* When the diffracting object has a periodic structure, for example in a diffraction grating, the features generally become sharper.

It is similar to what occurs when waves are scattered from a diffraction grating.

File: Joseph von Fraunhofer. jpg | Joseph von Fraunhofer, ( 1787-1826 ): first to studied the dark lines of the Sun ’ s spectrum, now known as Fraunhofer lines, first to use extensively the diffraction grating ( a device that disperses light more effectively than a prism does ), set the stage for the development of spectroscopy, making optical glass and achromatic telescope objectives.

Light from the star is analyzed by splitting it up by a diffraction grating, subdividing the incoming photons into a spectrum exhibiting a rainbow of colors interspersed by absorption lines, each line indicating a certain ion of a certain chemical element.

The idea that crystals could be used as a diffraction grating for X-rays arose in 1912 in a conversation between Paul Peter Ewald and Max von Laue in the English Garden in Munich.

A very large reflecting diffraction grating

In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions.

The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws.

This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821.

A grating has a ' zero-order mode ' ( where m = 0 ), in which there is no diffraction and a ray of light behaves according to the laws of reflection and refraction the same as with a mirror or lens respectively.

An idealised grating is considered here which is made up of a set of slits of spacing d, that must be wider than the wavelength of interest to cause diffraction.

Comparison of the spectra obtained from a diffraction grating by diffraction ( 1 ), and a prism by refraction ( 2 ).

Bragg diffraction is a consequence of interference between waves reflecting from different crystal planes.

The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption.

Ordinary pressed CD and DVD media are every-day examples of diffraction gratings and can be used to demonstrate the effect by reflecting sunlight off them onto a white wall.

Even if a reflecting telescope could have a perfect mirror, or a refracting telescope could have a perfect lens, the effects of aperture diffraction are unavoidable.

The remaining step in utilizing optical amplification to create an optical oscillator is to place highly reflecting mirrors at each end of the amplifying medium so that a wave in a particular spatial mode will reflect back upon itself, gaining more power in each pass than is lost due to transmission through the mirrors and diffraction.

Grating can also be a diffraction grating: a reflecting or transparent optical component on which there are many fine, parallel, equally spaced grooves.

It does this by reflecting a relatively multi-chromatic ( as compared to most lasers ) pulse off a series of two diffraction gratings, which splits them spatially into different frequencies, essentially the same thing a simple prism does with visible light.

For example, there are persons who are in physical science, in the field of mineralogy, trained in crystallography, who use only X-rays, applying only the powder technique of X-ray diffraction, to clay minerals only, and who have spent the last fifteen years concentrating on the montmorillonites ; ;

The photochemical reaction cells consisted of 10 mm. i.d. Pyrex tubing, 5.5 cm. long, diffraction effects being minimized by the fact that the light passed through only liquid-glass interfaces and not gas-glass interfaces.

He suggested that when there are only a few sources, say two, we call it interference, as in Young's slits, but with a large number of sources, the process be labelled diffraction.

* The diffraction angles are invariant under scaling ; that is, they depend only on the ratio of the wavelength to the size of the diffracting object.

Because the wavelength for even the smallest of macroscopic objects is extremely small, diffraction of matter waves is only visible for small particles, like electrons, neutrons, atoms and small molecules.

A citation to Astbury's earlier X-ray diffraction work was one of only eight references in Franklin's first paper on DNA.

due to diffraction, that can only remain true well within the Rayleigh range.

While crystals, according to the classical crystallographic restriction theorem, can possess only two, three, four, and six-fold rotational symmetries, the Bragg diffraction pattern of quasicrystals shows sharp peaks with other symmetry orders, for instance five-fold.

Each X-ray diffraction image represents only a slice, a spherical slice of reciprocal space, as may be seen by the Ewald sphere construction.

The beam has to have a large diameter so that only a small portion of the beam misses the sail due to diffraction and the laser or microwave antenna has to have a good pointing stability so that the craft can tilt its sails fast enough to follow the center of the beam.

For example, if the pinhole diameter is set to 1 Airy unit then only the first order of the diffraction pattern makes it through the aperture to the detector while the higher orders are blocked, thus improving resolution at the cost of a slight decrease in brightness.

Although originally she was to have worked on X-ray diffraction of proteins and lipids in solution, Randall redirected her work to DNA fibers before she started working at King's since Franklin was to be the only experienced experimental diffraction researcher at King's in 1951.

Wide-angle X-ray scattering is the same technique as small-angle X-ray scattering ( SAXS ) only the distance from sample to the detector is shorter and thus diffraction maxima at larger angles are observed.

Grazing incidence diffraction is used in X-ray spectroscopy and atom optics, where significant reflection can be achieved only at small values of the grazing angle.

Before the acceptance of the de Broglie hypothesis, diffraction was a property that was thought to be only exhibited by waves.

Conventional optical systems capture only the information in the propagating waves and hence are subject to the diffraction limit.

Not only does this cause some reduction in the amount of light the system collects, it also causes a loss in contrast in the image due to diffraction effects of the obstruction as well as diffraction spikes caused by most secondary support structures.

The technique is most commonly performed as powder diffraction, which only requires a polycrystalline powder.

The diffraction limit is only valid in the far field.

RHEED systems gather information only from the surface layer of the sample, which distinguishes RHEED from other materials characterization methods that also rely on diffraction of high-energy electrons.