Photonics Dictionary

An optical instrument that uses a yellow light of varying intensity with red and blue lights of fixed intensity to test for colorblindness.

Dispersion that occurs when the medium's index of refraction decreases as the frequency of the propagating light increases. For a given medium, some wavelength ranges may produce anomalous dispersion...

A spectral phenomenon in which the degree of the photoresponse of an illuminated semiconductor is determined by the wavelength composition of the incident light.

Irregular propagation of a wave due to variations in the medium's density or refractive index.

Color vision whereby abnormal proportions of three colors are needed for color matching.

Having human characteristics or behavior.

In image processing, methods of reducing image defects that result from false data. Techniques include sampling, linear intensity, filtering a high-resolution image to produce a low-resolution image,...

Characteristic of an absorber in the IR region, whereby absorption increases as a direct function of the intensity of the incident, continuous radiation.

A device that prevents electrons from a saturated pixel in a CCD imaging device from spilling into an adjacent pixel. The antiblooming gate drains a pixel of any charge in excess of its full-well...

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

A coating that is capable of stopping the condensation of moisture on an optical surface.

An antigen is any substance that is capable of triggering an immune response in an organism. Antigens are typically proteins or large polysaccharides, although other types of molecules can also act...

A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for...

Light-absorbing material that is applied to the back support of any bright image under inspection to prevent the formation of a secondary image.

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

Literally the opposite of resonance, antiresonance occurs when any variation in excitation frequency results in an increased response.

The point to which the extension of the straight line, reaching from the sun to the observer's eye after penetrating the atmosphere of the Earth, is projected.

An electrically conductive layer for carrying off static charges that might accumulate on a surface.

An APD detector, or avalanche photodiode detector, is a type of photodetector used to detect light or optical signals by converting incoming photons into electrical current. It operates based on the...

An instrument designed to measure the numerical aperture of an objective.

An opening or hole through which radiation or matter may pass.

A combination 80-column computer card containing a 35-mm microfilm frame. Reference data can be punched onto the card to facilitate retrieval of it on film.

The second adjustable iris diaphragm in an optical system. In the common microscope condenser system, it usually is located beneath the substage condenser on a transmitted light microscope. When the...

A loss of resolution or detail in a television signal caused by the size of the electron scanning beam.

The amplitude, polarization and phase contained in the field distribution over the aperture.

The formation of an image by a pinhole aperture that transmits radiation, such as gamma radiation.

Also known as a shadow mask, a perforated plate placed between the focusing and accelerating electrodes, and the tricolor phosphor screen in a color-television tube.

The ratio of the lens aperture to its focal length (1/f/#).

A physical constraint, often a lens retainer, that limits the diameter of the axial light bundle allowed to pass through a lens.

The point of a planet or comet's orbit that is farthest from the sun.

Also known as aplanatic lens. A lens corrected for spherical aberration and coma.

A system that satisfies the Abbe sine condition, and is free from spherical aberration and coma.

Aplanatic points refer to specific points in an optical system where certain aberrations, such as spherical aberration or coma, are minimized or eliminated. In an optical system, aberrations are...

An aplanatic surface is an optical surface that is specifically designed or shaped to minimize spherical aberration and coma. Spherical aberration is an optical aberration that occurs when light rays...