Photonics Dictionary

Observed when alterations in the luminous sterance at the contour of an object create the illusion of the outer zones appearing darker than the inner regions, despite the consistent luminance of the...

The deformation of a material at high levels of stress, often associated with elevated temperatures.

That wavelength at which the absorption of a given element or system begins to demonstrate an inconstant value.

The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is...

In an optical system, the aperture size at which the lens gives its best overall performance.

Relative to a light source, the frequency at which the source appears to fluctuate in light intensity half the time and remains constant during the other half.

The fusion frequency of flicker that is needed just to produce complete fusion and to assure the visual sensation of continuous illumination measured in cycles per second.

Illumination in which the light source is imaged at the object.

Recombination of only the light that is correctly dispersed by the first stage of a polychromator through its wide intermediate slit (common during Thomson scattering experimentation), which is...

A positioning slide mechanism with two rows of alternately crisscrossed cylindrical rollers.

Calculation of the probability of an interaction between two types of particles, such as light absorption, excitation or energy transfers. The probability that one incident particle will interact as...

Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects in the field of view. They were formerly made from a single strand of...

A signal-averaging technique that improves signal-to-noise ratio by comparing a sampled signal with a reference signal bearing some known relation to the received signal.

1. A defect inherent in a multiple-axis positioning system whereby an adjustment of one axis causes an undesired change in another; its severity depends upon the degree to which the positioning axes...

The positioning of two Nicol prisms so that their axes are at right angles to each other. With this arrangement, light transmitted by one prism will not be transmitted by the other.

A cryogenically cooled long-wave infrared (LWIR) camera is a specialized thermal imaging device designed to detect infrared radiation in the long-wave infrared spectrum, typically ranging from 8 to...

The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).

The spectrographic analysis of matter that is in a cooled state. Generally, a mechanical refrigerator is used to lower the temperature of the sample, allowing isolation and study of the sample and...

A cryostat is a device used to maintain very low temperatures, typically below the boiling point of liquid nitrogen (77 K or -196°C) or even lower. It provides a controlled environment for...

A solid with a structure that exhibits a basically symmetrical and geometrical arrangement. A crystal may already possess this structure, or it may acquire it through mechanical means. More than 50...

A diode with a semiconducting material, such as germanium or silicon, for one electrode, and a fine wire "whisker'' which lies on the semiconductor, as the other electrode. The low capacitance...

A crystal that may serve as a diffraction grating if mounted effectively.

A temperature-controlled container used to stabilize the temperature and resonant frequency of a crystal found in a crystal-controlled oscillator.

The naturally occurring crystalline form of silicon dioxide. It is slightly birefringent and exhibits rotary dispersion of light rays transmitted along the crystal axis, both right-hand and left-hand...

A system that applies a crystal as a diffracting agent to photograph the spectrum.

The axes of symmetry in a crystal structure. See also biaxial crystal; uniaxial crystal.

The internal lens of the eye. It is semielastic to permit changes in its power when focusing on objects at near distances.

Glass of special composition that is melted, formed into desired shapes, and subjected to a high-temperature treatment in which the glass undergoes a stage of nucleic formation, and a second stage,...

The photographic record of the diffraction pattern formed when x-rays pass through a crystal.

A CubeSat is a type of miniaturized satellite characterized by its standardized size and modular design. CubeSats are typically used for scientific research, technology demonstration, educational...

A method of resampling in which a 16-pixel neighborhood around a given pixel from the original image is used to calculate the final brightness value of that pixel in the corrected image.

Standard maintained by the International Commission on Radiological Units as a unit of radioactivity defined as the quantity of any radioactive nuclide in which the number of disintegrations per...

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.

On a display monitor, a small, mobile rectangle, cross-hair or pointer that locates a feature in an image that is the object of attention, or indicates where the next character will appear in word...

A lens aberration that causes a flat object surface to be imaged onto a curved surface rather than a plane.

A lens aberration in which the focal length varies radially outward from the center of the field. It has the effect of making a straight tangential line in the object appear curved in the image,...

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...

In computer graphics, intersection of a plane with a three-dimensional object to create a sectional view.