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  2. Vergence (optics) - Wikipedia

    en.wikipedia.org/wiki/Vergence_(optics)

    In geometrical optics, vergence describes the curvature of optical wavefronts. [1] Vergence is defined as. where n is the medium's refractive index and r is the distance from the point source to the wavefront. Vergence is measured in units of dioptres (D) which are equivalent to m −1. [1] This describes the vergence in terms of optical power.

  3. Luminous efficiency function - Wikipedia

    en.wikipedia.org/wiki/Luminous_efficiency_function

    The CIE photopic luminous efficiency function y(λ) or V(λ) is a standard function established by the Commission Internationale de l'Éclairage (CIE) and standardized in collaboration with the ISO, [1] and may be used to convert radiant energy into luminous (i.e., visible) energy. It also forms the central color matching function in the CIE ...

  4. Photopic vision - Wikipedia

    en.wikipedia.org/wiki/Photopic_vision

    The horizontal axis is wavelength in nm. Photopic vision is the vision of the eye under well-lit conditions (luminance levels from 10 to 10 8 cd/m 2). In humans and many other animals, photopic vision allows color perception, mediated by cone cells, and a significantly higher visual acuity and temporal resolution than available with scotopic ...

  5. Beam divergence - Wikipedia

    en.wikipedia.org/wiki/Beam_divergence

    Beam divergence. In electromagnetics, especially in optics, beam divergence is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the beam emerges. The term is relevant only in the "far field", away from any focus of the beam. Practically speaking, however, the ...

  6. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    White light is dispersed by a prism into the colors of the visible spectrum. The visible spectrum is the band of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light (or simply light). The optical spectrum is sometimes considered to be the same as the ...

  7. Spectral sensitivity - Wikipedia

    en.wikipedia.org/wiki/Spectral_sensitivity

    Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience, spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye.

  8. Fermat's principle - Wikipedia

    en.wikipedia.org/wiki/Fermat's_principle

    Fig. 1: Fermat's principle in the case of refraction of light at a flat surface between (say) air and water. Given an object-point A in the air, and an observation point B in the water, the refraction point P is that which minimizes the time taken by the light to travel the path APB. If we seek the required value of x, we find that the angles ...

  9. Free spectral range - Wikipedia

    en.wikipedia.org/wiki/Free_spectral_range

    The transmission of an etalon as a function of wavelength. A high-finesse etalon (red line) shows sharper peaks and lower transmission minima than a low-finesse etalon (blue). The free spectral range is Δλ (shown above the graph). The FSR is related to the full-width half-maximum δλ of any one transmission band by a quantity known as the ...