The ability of light to produce interference phenomena.
Refers to light “spreading out beyond the edges” of a small aperture or “bending around the corners” of an obstruction, into a region where—using strictly geometric optics reasoning—we would not expect to see it, and sets a limit on the resolution that can be achieved in any optical instrument. With a circular aperture such as the pupil, for example, the image of a point source of light formed on the retina—the point spread function (PSF)—in the absence of aberrations, takes the form of alternating bright and dark rings surrounding a bright central spot, the Airy disc, rather than a point.
Scattering of light by particles that occurs if the particle size is much larger compared to the wavelength of incident light. The interaction of light with the particle is usually sufficiently described by the laws of geometric optics (refraction and reflection). The formation of a rainbow, for example, is sufficiently described by refraction and reflection by raindrops.
Interference reveals the correlation between light waves and occurs when 2 light waves are brought together (superposition of waves), reinforcing each other and resulting in a wave of greater amplitude (ie, constructive or additive interference), or subtracting from each other and resulting in a wave of lower amplitude (ie, destructive or subtractive interference), depending on their relative phase.
Initially the acronym for Light Amplification by Stimulated Emission of Radiation.
Scattering of light produced by particles whose size is the same order of magnitude as the wavelength of incident light. Mie scattering caused by water droplets contributes to the white appearance of clouds. Similarly, Mie scattering caused by a cataract accounts for the whitish appearance of the lens under slit-lamp examination.
A measurement of the human visual system’s psychophysical response to light. Basically, photometry can be considered a subtype of radiometry that considers the varying sensitivity of the eye to different wavelengths in the visible spectrum.
Light is said to be polarized when the orientation of the electric field, as it oscillates perpendicularly to the direction of propagation, is not random. The polarization state can be pictorially represented by the path that the tip of the electric field vector traces with time as viewed along the propagation axis looking toward the source, and can be linear, circular, or elliptical.
The quantum theory of the interaction of light and matter that resolves the wave–particle confusion. The theory describes most of the phenomena of the physical world—including all observed phenomena of light—except for gravitational and nuclear phenomena.
Refers to the direct measurement of light in any portion of the electromagnetic spectrum. In contrast to the photometric measurements, radiometric measurements weight equally the energy transmitted at every wavelength of the electromagnetic spectrum.
Wavelength-dependent scattering that occurs when light interacts with particles much smaller than the wavelength of the light. The blue appearance of the sky during daytime and its reddish appearance during sunrise or sunset is due to Rayleigh scattering by atmospheric gas molecules. The bluish appearance of the cornea and lens (particularly noticeable in young eyes) under slit-lamp examination is also due to Rayleigh scattering by stromal collagen and lenticular fiber cells.