Photonics Dictionary: A

The alteration and reduction of color with the addition of white light. The perceived color shift that occurs as the monochromatic-white combination meets the eye and is interpreted by the brain. The...

The change in refractive index that occurs as acoustic vibrations are transmitted through an optical material.The index changes are periodic in relation to the frequency, spatial orientation, and...

With respect to photography, the change in the density-exposure relations, for small details of the photographic image, that is noted when compared with the density-exposure relations for large...

The equation devised by Sir G.B. Airy for the analysis of light diffraction near a caustic surface: (d2f/dz2) - zf = 0 where z represents the independent variable, and f is the value of the function.

The elimination of magnetic moments and decrease in magnetic susceptibility with a decrease in temperature due to the equal power of atomic magnets.

In an optical system having astigmatism, the distance between the tangential and sagittal image planes.

A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or...

The radiation-free transition that takes place within an ion, in which inner-shell vacancies in neutral atoms are filled by outer-shell electrons, thereby transferring energy to other electrons,...

A dispersion relation defined in order to value the reciprocal amount of dispersion. It is defined as the refractivity over the difference in index values of the shortest and longest visible...

Designed for the function of optical wavefront analysis. Shack-Hartmann camera aberration sensors use a lens array to image the wavefront to the CCD image plane. Live feedback may be applied through...

Optical surface damage due to abrasive rubbing. Abrasion damage affects are less than the thickness of the optical coating layers. Surface investigation may be achieved by aluminization of the coated...

Method of preserving the measured color value and color information as it is translated from differing devices. For example the output of a television display may be measured to have an identical...

A perfect diffuser that exists only as a concept, or a white with known spectral characteristics used as a reference in measuring absolute reflectance.

A doped or absorbing transparent medium cut or molded into a wedge in order to measure the real and imaginary components of the refractive index. An internally reflected Gaussian beam is interfered...

The transfer of energy from an incident electromagnetic energy field with wavelength or frequency to an atomic or molecular medium.

An absorption peak refers to a sharp increase or spike in the absorption of electromagnetic radiation at a particular wavelength or energy level. It is a distinctive feature in the absorption...

An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms, it measures acceleration. Accelerometers are widely used in various...

An achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

Cemented prisms of differing refractive indices which refract incident light and, due to differing refractive indices, will not spatially separate individual wavelengths.

The recorded interference pattern formed by the interference of two sound beams.

The optical reconstruction of image information contained in a sound field. First the diffraction pattern, formed by an object irradiated by ultrasonic rays, interferes with a mutually coherent...

An acousto-optic modulator (AOM) is a device that utilizes the interaction between sound waves and light waves to modulate or control the intensity, frequency, phase, or direction of laser beams. It...

Discipline within optical physics that addresses sound vibration, phonon effects and their influencing behavior within optical elements and systems.

That point in the electromagnetic spectrum at which an optical system focuses the most chemically effective rays.

Actinometry refers to the measurement of the intensity of radiation, particularly ultraviolet (UV) radiation or sunlight. It is commonly used in atmospheric science, environmental monitoring, and...

1. Synonymous with radioactivity. The intensity of a radioactive source illustrated as the number of atoms disintegrating in unit time, or as the number of scintillations or other effects observed...

In photography, the density gradient across an edge separating light from darkness, a physically measurable quantity that correlates well with subjectively observed sharpness of definition. By...

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

An apparatus used to determine the degree of adaptation of the eye under different conditions.

Advanced driver assistance systems (ADAS) refers to a set of safety features and technologies designed to assist drivers in the driving process and enhance overall vehicle safety. These systems use...

Agri-photonics refers to the application of photonics technologies in agriculture. Photonics involves the generation, manipulation, and detection of light and other forms of radiant energy whose...

An alexandrite laser is a solid-state laser that utilizes a synthetic crystal made from the rare earth element alexandrite (BeAl2O4:Cr3+). This crystal is capable of emitting laser light in the...

An old name for the rotating arm moving about an axis of rotation over a divided circle used to measure angles. Now the term refers to a small stadia telescope mounted over a ruler for use in...

Also known as all-glass fiber. A fiber with both a silica core and a silica cladding, regardless of the presence of a polymer overcoat or buffer.

Any fluorescence in which the wavelength of the emitted light differs from that of the absorbed light.

Left- and right-hand circularly polarized beams that are produced at different velocities by passing plane-polarized light through an optical substance. When recombined, they exhibit different phases...

A photocell having an alloy junction formed by combining an indium disc with a thin wafer of N-type germanium.

The disordered, glassy solid state of a substance, as distinguished from the highly ordered crystalline solid state. Amorphous and crystalline phases of the same substance differ widely in optical...

An optical device, such as a Nicol prism, capable of producing plane-polarized light, and used for detecting the effect of the object on plane-polarized light produced by the polarizer.

A term used to denote a difference in magnification along mutually perpendicular meridians. Anamorphic systems are basically image-distorting systems, such as those used in motion pictures, that...

A type of distortion in which the magnification varies in different orientations, the directions of maximum and minimum magnification being orthogonal.

An optical system with different focal lengths or magnification levels in perpendicular planes to the optical axis.