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Special use of Latin lēns a lentil (from its shape)
- 1. A piece of glass, or other transparent substance, with two curved surfaces, or one plane and one curved surface, serving to cause regular convergence or divergence of the rays of light passing through it.
- 2. some analogous device, as for affecting sound waves, electromagnetic radiation, or streams of electrons.
- 3. Geology . a body of rock or ore that is thick in the middle and thinner toward the edges, similar in shape to a biconvex lens.
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element. A compound lens is an array of simple lenses (elements) with a common axis; the use of multiple elements allows more optical aberrations to be corrected than is possible with a single element. Lenses are typically made of glass or transparent plastic. Elements which refract electromagnetic radiation outside the visual spectrum are also called lenses: for instance, a microwave lens can be made from paraffin wax.