Photonics Dictionary

In optical character recognition, the mechanical or electronic transducer used to detect the level of illumination present in the various portions of an illuminated sample region.

In optics, the production of maxima and minima by the superimposition of two sets of interference fringes from light of two different wavelengths.

The end of an optical fiber farthest from the source of illumination.

In astronomy, the relation that states that the intensity of a star's visible radiation is inversely proportional to the square of the distance from which it is viewed.

A general term referring to the situation in which an image is not a true-to-scale reproduction of an object. The term also is used to connote the temporal alteration of the signal's waveform shape....

The limitation on performance imposed by the distortion of a received signal rather than its amplitude or power.

A device similar to distributed feedback lasers in construction and operation, but in which the period grating that produces feedback is removed from the gain region to simplify fabrication. The...

A distributed feedback laser (DFB laser) is a type of semiconductor laser diode designed to emit coherent, narrow-bandwidth light with precise control over the wavelength. It achieves this through a...

A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...

A scanning technique in optical character recognition in which an array of photocells is used to scan each character to determine its horizontal and vertical characteristics.

A primitive crystal possessing two plane surfaces that form a dihedral angle bisected by another plane surface.

A single wavelength of light that matches the color of a given sample when combined in suitable proportions with white light and a suitable adjustment of intensity.

In the context of materials science and semiconductor physics, doping refers to the intentional introduction of impurities into a semiconductor material in order to alter its electrical properties....

The effect produced on a wave frequency because of the relative motion of a source or an observer. The radiation emitted from a source that moves away from an observer appears to be of lower...

The theory established by Christian J. Doppler in 1842 that states that the rate of change in distance between a perceiver and a radiation source determines the change in frequencies.

A signal traveling from transmitter to receiver that has an altered frequency due to the Doppler effect.

The principle stating that the displacement of spectrum lines is determined by the distance between, and relative velocity of, the observer and the light source. When distance decreases, the lines of...

An imaging process, similar to specific Doppler mapping radar techniques, that utilizes a laser, an optical imaging system, and a line array of photodetectors and spectrum analyzers. The laser...

A display format consisting of small light-emitting elements arranged as a two-dimensional array. Various elements are energized to depict a character. The typical matrix is 5 x 7 dots.

Measurement derived from calculation when incident flux of a negative is entirely diffuse and all radiation transmissions are included.

The separation of unpolarized light into two plane-polarized elements by a doubly refracting crystal. When a crystal, such as calcite, is placed between the eye and a pinhole in a card, two bright...

A defect of a binocular instrument causing two images to be seen separately instead of being fused. It is caused when the optical axes of the two telescopes are not parallel. In minor cases, the eyes...

A spectrophotometer in which the beam emitted by the radiation source is split into beams that travel through the sample and a reference cell and are subsequently recombined to fall on the detector....

Double-clad fiber (DCF) is a specialized optical fiber that features two concentric cladding layers surrounding a core. The design of double-clad fibers allows them to be used in various...

The formation of an interferogram by means of two holograms on the same recording medium, often used for determining small changes in an object. One hologram produces a primary image that constitutes...

A prism block that, when used with a lens, is capable of forming two images of one object.

A device used to create a light output that exceeds light input, the energy being provided by an electric field. It consists of a photoconductive layer with an electroluminescent layer between plates...

A hologram having an object wave that has been transmitted through the transparent object media to a mirror, reflected again and recorded on a medium.

Interferometric measurement of the interference pattern recorded when a complex object is illuminated by two laser pulses that interfere and form the pattern to be evaluated.

Holographic recording whereby the object is illuminated by two pulses, separated by a time interval, from a Q-switched laser source. Each pulse is divided into reference and object beams, and...

An astronomical scanning technique for capturing images of stars without moving the sensor. To perform a drift scan, a CCD sensor's readout rate must be synchronized with the motion of celestial...

The minimum electrical current input needed to initiate lasing.

A microscope objective designed to be used without liquid between the cover glass and the objective, or, in the case of metallurgical objectives, between the objective and the specimen.

A package for electronic components that is suited for automated assembly into printed circuit boards. The DIP is characterized by two rows of external connecting terminals or pins, which are...

A gas laser equipped with Brewster windows and concave mirrors (having unlike reflective properties) at each end of the tube to produce two separate wavelengths at the same time.

Dual-axis laser is a laser device or system capable of emitting laser beams along two orthogonal axes (typically X and Y axes) concurrently. This allows for precise control and manipulation of the...