Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it.

  • Most optical phenomena can be accounted for using the classical electromagnetic description of light (wavelength, frequency and intensity) but they can also be modelled as particles called photons.
  • Optics is both a field of physics and an area of engineering. It has been used to create many useful devices, including eyeglasses, cameras, telescopes, and microscopes. Many of these devices are based on lenses, which can focus light and produce images of objects that are larger or smaller than the original.
  • New discoveries are being made in the field of optics For example, The first working fibre-optic data transmission system was demonstrated in 1965. Less than 60 years later, fibre optics are now used to send vast amounts of data through thin optical fibre around the world.
  • Contemporary specializations within the field of optics include:
    • Geometrical optics is a branch of optics that deals with the behaviour of light as a collection of rays that propagate in straight lines and are subject to reflection and refraction.
    • Physical optics is a branch of optics that describes the behaviour of light as both a wave and a particle and includes wave phenomena such as diffraction and interference that are not explained by geometrical optics.
    • Quantum mechanics is a branch of physics that describes the behaviour of light as both a wave and a particle and investigates the interactions between light and matter.
About geometrical optics
  • Geometrical optics, also known as ray optics, is one of the two main branches of optics, the other being physical optics.
  • Geometrical optics is based on the assumption that light travels as a straight line and is useful in explaining various optical phenomena, including reflection and refraction, in simple terms.
  • Geometrical optics is a useful tool in analyzing the behaviour of optical systems, including the image-forming process and the appearance of aberrations in systems containing lenses and prisms.
  • The underlying assumptions of geometrical optics include that light rays:
    • Propagate in straight-line paths when they travel in a uniform medium.
    • Bend, and in particular, refract, at the interface between two dissimilar media.
    • Follow curved paths due to the varying refractive index of the medium.
    • May be absorbed as photons and transferred to the atoms or molecules of the absorbing material, causing the absorbing material to heat up or emit radiation of its own.