Photonics Dictionary

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...

A digital camera is a device that captures and records still images or video in digital format. Unlike traditional film cameras, which use photographic film to capture and store images, digital...

Digital signal processing (DSP) refers to the manipulation and analysis of signals, which are representations of physical quantities that vary over time or space. In the context of DSP, these signals...

For a lens with an obscured or noncircular aperture, the focal length divided by the effective aperture.

A charged elementary particle of an atom; the term is most commonly used in reference to the negatively charged particle called a negatron. Its mass at rest is me = 9.109558 x 10-31 kg, its charge is...

A single number, defined by the computer program or the user that expresses the performance of an optical system. Also known as merit function and defect function, the error function comprises...

An instrument used to measure the light from a scene to be photographed and to indicate the camera lens and shutter settings required to expose the film correctly. The exposure time required in a...

Extreme ultraviolet (EUV) refers to a specific range of electromagnetic radiation in the ultraviolet part of the spectrum. EUV radiation has wavelengths between 10 and 124 nanometers, which...

The expression denoting the ratio of the equivalent focal length of a lens to the diameter of its entrance pupil.

The simultaneous collection of two or more signals at a single location. In a digital computer, it refers to the number of inputs that can be accommodated by a particular logic circuit.

The distribution of one signal to more than one location. In a digital computer, it refers to the number of outputs that can be fed by a particular logic circuit.

The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds the SNR of a scanning spectrometer in the same time by a factor proportional...

The principle that a light ray extending from one point to another will, after any number of reflections and refractions, follow the path requiring the least transit time. This is also known as the...

A fiber optic imaging bundle is a specialized optical device composed of multiple optical fibers bundled together. Each fiber optic strand within the bundle acts as a conduit for transmitting light....

The number of fields scanned per second in a television system. The US standard is 60. Also called field frequency.

A device that holds a number of filters and allows the filter with the desired characteristics to be rotated into an optical aperture.

A finite version of Shannon's sampling theorem that states that a class of functions can be reconstructed exactly by a sufficient number of spectral samples; the reconstructed function is an explicit...

Any of a number of instruments that uses a flame to vaporize a solution of the chemical being analyzed so that light may be passed through the vapor. Monochromation of the transmitted light is...

Optical glass that possesses a refractive index equal to or less than 1.5, and an Abbe number that ranges from 62 to about 85.

The number of times per second that the frame of a television system is completely scanned. In the United States, 30 per second is the standard frame frequency.

The number of separate images exposed by a cine camera in a second or the number illuminated by a cine projector in a second. By varying the number of images recorded per second, films can be created...

With reference to electromagnetic radiation, the number of crests of waves that pass a fixed point in a given unit of time, in light or other wave motion. Expressed in hertz or cycles per second.

In a lens, the square of the radius of its aperture divided by the product of the focal length and the wavelength. It measures the importance of diffraction in the image formed by the lens. A small...

The number of electrons that each pixel of a charge-coupled device can hold without overflowing and causing blooming.

A system of mirrors that can be used to direct light from a single laser source into any one of a number of separate optical fibers.

Formula used in convection study to express the ratio of buoyant force to viscous force.

A framework or latticework having an even arrangement of rods, or any other long narrow objects with interstices between them, used to disperse light or other radiation by interference between wave...

A method of determining the abrasion resistance of very hard materials by passing a weighted wiper blade across them in a sand-water slurry for a specified number of times.

A high-sensitivity camera is a type of camera designed to perform well in low light conditions, capturing clear and detailed images with minimal noise. These cameras typically feature advanced sensor...

A graphic representation of a distribution function such as frequency by means of rectangles whose widths represent the intervals into which the observed values' range is divided and whose heights...

In television, the number of individual pixels that can be distinguished in a horizontal scanning line; also called horizontal definition.

A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide range of wavelengths within the electromagnetic spectrum, typically from...

An image intensifier, also known as an image intensification tube or image intensification device, is a specialized electronic device used to amplify low-light-level images to make them visible to...

Qualitatively, the inverse of the amount of velocity produced by the application of a sinusoidal force to a system; therefore, if velocity is high, impedance at that point is low. Quantitatively,...

An unbounded quantity, an indefinitely large number. Infinity is commonly expressed by the symbol ∞.

Instantaneous field of view (iFOV) is a term commonly used in the context of remote sensing, imaging systems, and optical instruments. It refers to the specific portion of a scene that an optical...

A type of laser for which a large number of the components can be fabricated in or upon a single substrate.

One of a number of nuclides characterized by an identity between their mass numbers, but each having a different atomic number.

The higher throughput obtained with an FTIR device compared with traditional spectrometers that need slits to achieve resolution. The advantage differs according to wave number and resolution.

In an interlaced scanning electro-optical system such as television, the system resolution will be less than the number of active scan lines because of the random phase nature of the object being...

An imaging device originally created to image whole mouse brain volumes at microscopic resolution. The main component of the instrument is an automated microtome and microscope capable of producing...

A group of single emitter laser diodes, usually arranged vertically or horizontally with respect to each other. The power output of the array increases in direct proportion to the number of single...

Laser marking is a process in which a laser beam is used to mark or engrave a surface by altering its properties or appearance. This technique is widely used for labeling, identification, and...

Laser parameters are the characteristics that define the behavior and performance of a laser. These parameters can be categorized into several groups: spatial, temporal, spectral, and operational. ...

The mechanical structure that holds a number of individual lens elements.

A lens blank is a piece of optical material in a raw, unfinished state, typically in the form of a disk or block, from which lenses are eventually fabricated. Lens blanks are made from various...