Structural coloration in the context of "Dragonflies"

A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterised by a pair of large, multifaceted, compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.

Dragonflies can be mistaken for the closely related damselflies, which make up the other odonatan infraorder (Zygoptera) and are similar in body plan, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Dragonflies make use of motion camouflage when attacking prey or rivals.

Teal is a dark cyan color. Its name comes from that of a bird, the Eurasian teal (Anas crecca) which has a similarly colored stripe on its head. The word is often used colloquially to refer to shades of cyan in general.

It can be created by mixing cyan into a green base, or deepened as needed with black or gray. It is also one of the first group of 16 HTML/CSS web colors. In the RGB model used to create colors on computer screens and televisions, teal is created by reducing the brightness of cyan to about one half.

Cetonia aurata, called the rose chafer or the green rose chafer, is a beetle, 20 millimetres (3⁄4 in) long, that has a metallic structurally coloured green and a distinct V-shaped scutellum. The scutellum is the small V-shaped area between the wing cases; it may show several small, irregular, white lines and marks. The underside of the beetle has a coppery colour, and its upper side is sometimes bronze, copper, violet, blue/black, or grey.

Cetonia aurata should not be confused with the North American rose chafer, Macrodactylus subspinosus, or with the rarely seen noble chafer, Gnorimus nobilis, which is very similar to the rose chafer. One way to identify Cetonia aurata is to look at its scutellum; on the noble chafer the scutellum is an equilateral triangle, but on the rose chafer it is an isosceles triangle.

In optics, a diffraction grating is a grating with a periodic structure of appropriate scale so as to diffract light, or another type of electromagnetic radiation, into several beams traveling in different directions (i.e., different diffraction angles) known as diffracted orders. The emerging coloration is a form of structural coloration. The directions or diffraction angles of these beams depend on the wave (light) incident angle to the diffraction grating, the spacing or periodic distance between adjacent diffracting elements (e.g., parallel slits for a transmission grating) on the grating, and the wavelength of the incident light. Because the grating acts as a dispersive element, diffraction gratings are commonly used in monochromators and spectrometers, but other applications are also possible such as optical encoders for high-precision motion control and wavefront measurement.

For typical applications, a reflective grating has ridges or "rulings" on its surface while a transmissive grating has transmissive or hollow slits on its surface. Such a grating modulates the amplitude of an incident wave to create a diffraction pattern. Some gratings modulate the phases of incident waves rather than the amplitude, and these types of gratings can be produced frequently by using holography.