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114 terms

Photonics Dictionary

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fiber optic plate -> fiber optic faceplate

A plate made up of thousands of glass fibers arranged parallel to one another, i.e., in a coherent bundle, and fused together so that it is hermetically tight. It transfers an image from one plane to...

flare

Nonimage-forming light, concentrated or diffuse, that is transmitted through the lens to the image. It is frequently the result of reflections from lens surfaces, a lens barrel, shutter or lens mount.

flashtube -> electronic flash unit

A small xenon-filled tube with metal electrodes fused into the ends. The gas flashes brilliantly when a condenser is discharged through the tube. The duration of the flash is primarily dependent upon...

flat-field frame

A frame taken with a CCD camera of a surface that is evenly illuminated by diffuse light. This frame shows irregularities in the light-sensing ability of the CCD, such as electronic defects and dust...

fluorescent protein

Fluorescent proteins are proteins that exhibit the property of fluorescence, which is the ability to absorb light at a specific wavelength and emit light at a longer wavelength. These proteins are...

Fresnel lens

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

functional near-infrared spectroscopy

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures changes in hemoglobin concentration in the brain. It utilizes near-infrared light to penetrate the...

fusion splice

A splice accomplished by the application of localized heat sufficient to fuse or melt the ends of two lengths of optical fiber, forming a continuous single fiber.

gain

Also known as amplification. 1. The increase in a signal that is transmitted from one point to another through an amplifier. A material that exhibits gain rather than absorption, at certain...

glass

A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or phosphoric oxides. Common window or bottle glass is a mixture of soda,...

global radiation

The total radiation, both solar and diffuse sky, that is incident to a unit's horizontal surface.

ground glass

A plate of glass in which a face has been frosted by grinding or etching. It diffuses light by scattering in directions close to the incoming beam, but the light falls off rapidly at larger angles...

holographic interferometry

The interferometric analysis of a complex object by utilizing the three-dimensional hologram. By causing a laser beam to diverge into two directions, one of which directly strikes a holographic...

hydroscopic

Designed to observe objects below the surface of water. Not to be confused with hygroscopic.

integrating sphere

A hollow sphere coated internally with a white diffusing material and provided with openings for incident beam, specimen and detector used for measuring the diffuse reflectance or transmittance of...

interstitial absorbing coating

An absorbing coating medium between fibers, used in some fused fiber optic plates to absorb unwanted light. Such coatings are sometimes called EMA (extramural absorption).

Kubelka-Munk theory

A two-flux theory in which the radiation is assumed to be composed of two oppositely directed radiation fluxes through a continuous medium. The theory has been widely used to relate the total diffuse...

Lambert's cosine law

Flux per unit solid angle leaving a surface in any direction is proportional to the cosine of the angle between that direction and the normal to the surface. A material that obeys Lambert's cosine...

laser powder bed fusion

Laser powder bed fusion (LPBF) is a type of additive manufacturing (AM) or 3D printing technology that uses a high-power laser to selectively fuse or melt layers of powdered material to build up a...

laser sintering

Laser sintering is an additive manufacturing (AM) or 3D printing technology that involves using a laser to selectively fuse powdered materials, typically polymers or metals, layer by layer, to create...

laser speckle

Sparkling granular pattern that is observed when an object diffusely reflects coincident laser light. Speckle appears as an irregularity in many holographs but has been exploited as a measurement...

light diffusion

Light diffusion refers to the process by which light is scattered or spread out in various directions as it interacts with a medium or material. Unlike direct transmission through a transparent...

lumen

A lumen is a unit of measurement used to quantify the amount of luminous flux, which is the perceived power of light. In other words, the lumen measures the total amount of visible light emitted by a...

luminance factor

Ratio of the luminance of a specimen to that of a perfect reflecting or transmitting diffuser identically illuminated.

machine vision lighting

Machine vision lighting refers to the use of specific lighting techniques and equipment in the field of machine vision, which is a technology that enables machines to capture and interpret visual...

machine vision system

A machine vision system is an integrated combination of hardware and software components designed to capture, process, and analyze images to perform automated inspection, measurement, and quality...

major

A blank to which a piece of glass of a different refractive index will be fused to form a multifocal lens.

mixed reflection

The simultaneous occurrence of specular and diffuse reflection.

mixed transmission

The simultaneous occurrence of direct and diffuse transmission.

moving aperture technique

Method for reducing laser speckle in which the object field comes from a real diffuse object or the reconstructed object field from a hologram. During recording of the image, an aperture is moved in...

multifibers

An array of optically distinct fibers that are fused into one strand. They are used to keep the resolution efficiency of the smaller, single fibers and eliminate difficulty in handling. Their...

near-infrared camera

A near-infrared (NIR) camera is an imaging device designed to capture images in the near-infrared region of the electromagnetic spectrum. The near-infrared spectrum typically extends from about 700...

opal lamp

A tungsten filament lamp that uses an opal glass bulb to diffuse light.

optical axis

The imaginary line passing through both the centers of curvatures of the optical surfaces of a lens or mirror; the optical centerline for all the centers of an optical element(s) of an optical...

optical materials

Optical materials refer to substances or compounds specifically chosen for their optical properties and used in the fabrication of optical components and systems. These materials are characterized by...

perfect diffuser

photometric sphere -> integrating sphere

A hollow sphere coated internally with a white diffusing material and provided with openings for incident beam, specimen and detector used for measuring the diffuse reflectance or transmittance of...

planar access coupler

Low-insertion-loss fiber coupler fabricated from a sheet of light-sensitive material laminated onto a fused quartz substrate and exposed through a suitable mask. After development of the plastic...

plastic jackets

The direct cladding used for fused silica cores to create large numerical aperture fibers and used as overcoats to glass-clad fibers to reduce microbend loss and increase mechanical protection.

plastic optics

Plastic optics refers to optical components or systems that are made from transparent plastic materials, as opposed to traditional optical components made from glass or other materials. Plastic...

pulse energy thermography -> pulse video thermography

A noncontact, nondestructive method of measuring defects in thin composite materials, using a xenon flashtube to generate heat in a sample. A thermal imaging system detects differences in the rates...

pulse video thermography

pulsed-dye laser

A laser with a gain medium consisting of an organic dye, which is carbon-based. The dye is mixed with a solvent, allowing the molecules to diffuse evenly throughout the liquid. The dye medium is...

quartz

See crystal quartz; fused quartz.

radiance factor

Ratio of the radiance of the specimen to that of a perfect reflecting or transmitting diffuser identically irradiated.

radiant reflectance -> reflectance

The ratio of reflected flux to incident flux. Unless otherwise specified, the total reflectance is meant; it is sometimes convenient to divide this into the sum of the specular and the diffuse...

reference white

The light from a nonselective diffuse reflector due to the standard illumination of the scene to be televised.

reflectance

The ratio of reflected flux to incident flux. Unless otherwise specified, the total reflectance is meant; it is sometimes convenient to divide this into the sum of the specular and the diffuse...

reflectance factor

Ratio of the directionally reflected flux to that reflected in the same direction by a perfect reflecting diffuser identically irradiated or illuminated.

reflectance spectrophotometer

An instrument that spectrally analyzes the flux reflected from a material. The reflected flux may be total, diffuse or specular. Often the instrument measures the reflectance factor instead of the...

Photonics Dictionary