The size of the aperture (or object) determines the extent of diffraction, with the most significant diffraction occurring when the aperture is of the same order of magnitude as the wavelength of the wave. Diffractionĭiffraction is the spreading out of a wave when it passes through an aperture (gap/hole) or around an object. IMPORTANT NOTE: If a wave enters a medium at 90º to the surface (parallel to the normal) it is not refracted. The angle of refraction is greater than the angle of incidence.The angle of refraction is less than the angle of incidence.The angle of refraction is larger or smaller than the angle of incidence depending on how the speed changes: Nano-scale materials are researched and used to produce photo tonic iridescent materials.Refraction occurs because waves travel at different speeds in different mediums and this change in speed is caused by differences in density between the mediums. These materials are used to produce iridescent appliances like CDs, DVDs, certain kitchen tools, decorative lights, and decorative illumination. Iridescent materials: Based on natural iridescence, certain materials like optic discs, pearls, thin films, and glazes are produced artificially. Types of iridescence in Earth materials include labradorescence, adularescence, aventurescence, and opalescence. In natural Earth materials like rocks, minerals (quartz), and gemstones (opal, fire agate) iridescence provides unique natural color patterns which improve their aesthetics. Animals exhibit iridescence adaptation to distinguish their species, choose and attract mates, or camouflage and protect them from prey. ![]() According to the change in the viewing angle, different colors can be observed as per their wavelength. When light is shown on certain microscopic structures on the feathers of the bird or the wings of insects, nacre of shells or pearls, and other parts of certain organisms, the light gets refracted and split into various components. In nature: Birds like peacocks or hummingbirds and insects like butterflies or bees exhibit iridescence due to their structural coloration. The tiny water droplets or ice particles cause the incident light from the sun’s rays to diffract and scatter leading to iridescence and the wonderful color patterns on the cloud. In atmosphere: Cloud iridescence or irisation produces amazing rainbow color patterns on the cloud. Iridescence can be observed all over the universe. Refraction: Optically anisotropic substances like cellophane undergo double refraction when monochromatic light is shown upon it and will create iridescence. When a CD is flipped slowly, varying color patterns can be observed due to iridescence. Diffraction gratings on the surface, also known as grooves, of certain organisms or structures like CDs, prisms etc. This phase shift and internal reflection of light amplifies the original incident light and attenuates the intensity of the light, resulting iridescence.ĭiffraction: When a ray of light is diffracted from a photo tonic iridescent structure at a particular wavelength then the surface will emit a ray of rainbow colors due to the change in intensity of light with each change in the angle of viewing, producing iridescence. The reflected light from the bottom layer meets the reflected light from the top layer.ĭepending upon the distance traveled by the light, light intensity and the time of reflection between both the layers the light bends through both surfaces and causes a phase shift of the wavelength of the incident light. When light passes through the first layer of an iridescent surface like a soap bubble, some of the light is reflected by the top layer and some are reflected by the bottom layer. ![]() If two waves have the same phase or wavelength, then their crests and troughs will meet each other and align perfectly on top of each other leading to the interference of light. The crest of the wave is the highest point the medium rises to and the trough of the wave is the lowest point to which the medium drops. ![]() Thin-film Interference: Light is a wave that has crests and troughs.
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