Optics facts for kids
Optics is the science of light and how it interacts with the world. Optics explains how rainbows exist, how light reflects off mirrors, how light refracts through glass or water, and what splits light shining through a prism. In addition to visible light in the standard "spectrum" of red, orange, yellow, green, blue, indigo, and violet, optics also deals with invisible parts of the whole electromagnetic spectrum of which visible light is but a small part.
Optics is both a science and an area of engineering. It has been used to make many useful things, including eyeglasses, cameras, telescopes, and microscopes. Many of these things are based on lenses, which focus light and can make images of things that are bigger or smaller than the original.
While optics is an old science, new things are still being discovered in it. Scientists have learned how to make light travel through a thin optical fiber made of glass or plastic. Light can go long distances in a fiber. Fibers are used to carry phone calls and the Internet between cities.
Images for kids
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A researcher working on an optical system
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The Nimrud lens
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Alhazen (Ibn al-Haytham)
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Reproduction of a page of Ibn Sahl's manuscript showing his knowledge of the law of refraction.
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The first treatise about optics by Johannes Kepler, Ad Vitellionem paralipomena quibus astronomiae pars optica traditur (1604)
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Cover of the first edition of Newton's Opticks (1704)
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When oil or fuel is spilled, colourful patterns are formed by thin-film interference.
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Conceptual animation of light dispersion through a prism. High frequency (blue) light is deflected the most, and low frequency (red) the least.
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Dispersion: two sinusoids propagating at different speeds make a moving interference pattern. The red dot moves with the phase velocity, and the green dots propagate with the group velocity. In this case, the phase velocity is twice the group velocity. The red dot overtakes two green dots, when moving from the left to the right of the figure. In effect, the individual waves (which travel with the phase velocity) escape from the wave packet (which travels with the group velocity).
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The effects of a polarising filter on the sky in a photograph. Left picture is taken without polariser. For the right picture, filter was adjusted to eliminate certain polarizations of the scattered blue light from the sky.
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Experiments such as this one with high-power lasers are part of the modern optics research.
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VLT's laser guide star
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The Ponzo Illusion relies on the fact that parallel lines appear to converge as they approach infinity.
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Illustrations of various optical instruments from the 1728 Cyclopaedia
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Photograph taken with aperture f/32
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Photograph taken with aperture f/5
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A colourful sky is often due to scattering of light off particulates and pollution, as in this photograph of a sunset during the October 2007 California wildfires.
See also
In Spanish: Óptica para niños
