Photonics Dictionary

Three filters used in making a color print of a color negative, red, green and blue-violet, respectively. Each filter transmits about one-third of the visible spectrum onto the print.

A bulk crystalline optic which permits the propagation of light through a volume of index altered material. The variation in refractive index along the material volume is due to a piezoelectric...

The process of adjusting input pixel by pixel at the filter plane to adapt to nondeal phase behavior in an optical correlator.

Broadband radiation emitted by a laser that does not transmit through the optical element. It can be removed by filtering.

An image that can be studied three-dimensionally through a pair of complementary color filters composed of two superimposed views.

A system in which a sequence of direct measurements of the target position is fed into a tracking filter that may produce refined estimates of past, present and future target positions.

A laser radar application in which a sequence of direct measurements of target position is fed into a tracking filter to produce refined estimates of both present and future target positions.

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,...

The use of a variable transmission filter at the aperture stop of a lens to modify its diffraction pattern. Reduced transmission at the center of the aperture will favor performance at high...

A filter that suppresses a given range of frequencies, transmitting only those above and below that band. Also called bandstop filter.

The range of frequencies that will pass through a filter or other device. Synonymous with passband.

A filter with a transmission that is high for a particular band of frequencies, but that falls to low values above and below this band.

Birefringence is an optical property of certain materials that causes them to exhibit different refractive indices for light of different polarizations. In other words, when light passes through a...

A filter that transmits light in a series of sharp, widely spaced wavelength bands by its sandwich construction of alternating layers of polarizing films and plates cut from birefringent crystal.

A filter that separates light into many colors via Bragg's law. Generally refers to a fiber Bragg grating used in optical communications to separate wavelengths.

A broadband filter is an electronic or electromagnetic device designed to pass a range of frequencies or signals within a specified bandwidth while attenuating or rejecting signals outside of that...

An electric filter that is characterized by a passband of the flattest possible shape.

A transparent powdered solid immersed in a liquid or plastic of similar refractive index but widely different dispersion; used to isolate narrow spectral regions.

The photographic filming of the action of x-ray images recorded on a fluorescent screen by means of large lens apertures and highly sensitive filters.

An optical interference coating, vacuum-deposited on a circular substrate, whose transmission characteristics may be varied by physical rotation.

A means of illumination from which the infrared component has been removed by absorption or reflection filters within the condenser system.

A filter that serves to alter the color temperature and the mired value of the radiation emitted by a source.

An instrument that uses a beam of light to scan a color transparency, and three differently filtered photosensors to record the transmitted beam, as a means of producing three exposed separation...

A device containing two photocells behind deep red and blue filters to measure color temperatures. The amplifier gain is adjusted to give a set reading of one photocell; the reading of the other is a...

A photometer that uses a set of color filters to measure the intensity of light in various regions of the spectrum.

A filter that passes a series of wavelength regions that are at equal distances from one another, such that its output resembles the teeth of a comb. In video transmission, a comb filter is used to...

A filter used in photography to change the spectral composition of light entering a camera, or to adjust color balance during printing.

Also known as clear glass or clear filter. The clear glass plate is used to simulate a filter, in converging or diverging light, to maintain focus.

A transducer composed of more than one high-pass, bandpass, low-pass or band-elimination filter.

A confocal resonator, also known as a confocal cavity or confocal laser resonator, is a type of optical resonator configuration used in laser systems. The term confocal in this context refers to the...

Technique that uses high-pass filtering to reduce the local average to zero for all regions of the picture and then applies a gain factor equal to the reciprocal of the local standard deviation to...

A filter designed to improve contrast in an imaging system. For visual and black and white photosystems, a yellow filter is used.

One area of image enhancement, accomplished by spatial filtering schemes, that usually involves attenuation of phase changes in the complex amplitude over a limited region of the Fourier spectrum of...

A technique used in integrated optics where a groove is cut on a substrate surface and covered by a thin film to facilitate the construction of filters, resonators, beamsplitters and grating couplers...

A bandpass filter with piezoelectric crystal components for the passage or impedance of electrical signals of various frequencies.

A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments. Preventive measures include slow-starter circuits, filtering and static control.

A custom optic refers to an optical component that is designed, manufactured, and tailored to meet specific requirements or applications. These optics can include lenses, mirrors, prisms, filters, or...

1. In detector technology, the long wavelength at which detector response falls to a set percentage (usually 20 or 50 percent). 2. In fiber optics, the shortest wavelength at which a fiber transmits...

In filter terminology, that wavelength where the filter transmission increases beyond 5 percent.

A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively transmit or reflect certain wavelengths of light while simultaneously absorbing...