Photonics Dictionary

The logarithm of the reciprocal of diffuse transmittance. Diffuse density results when a sample is diffusely illuminated.

Light emitted by one or more sources and characterized by a high degree of scatter.

Modulation transfer function of an optical element when used for transporting images from a lambertian source such as phosphors.

Ratio of diffusely reflected flux to incident flux.

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties of materials, particularly in the field of spectroscopy. Unlike traditional...

Nonspecular reflection from a rough surface.

A reflecting surface that scatters radiation that is incident on it, thus producing diffuse reflection.

Use of a photoelectric receiver to sense an object's presence by detecting a small amount of the emitter's light that is diffusely reflected by the object.

Transmission accompanied by diffusion or scatter to the extent that there is no regular or direct transmission.

The ratio of diffusely transmitted flux to incident flux.

A color filter that is designed to gradually increase or decrease its absorption with wavelength.

An optical diffuser is an optical component or material designed to scatter or diffuse light that passes through it. It is used to create a more even or uniform illumination, reduce glare, or soften...

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

A surface that obeys Lambert's cosine law and has a reflectance of unity.

Method of preserving the measured color value and color information as it is translated from differing devices. For example the output of a television display may be measured to have an identical...

A perfect diffuser that exists only as a concept, or a white with known spectral characteristics used as a reference in measuring absolute reflectance.

Diffuse light emitted by the atmosphere due to the excitation of particles of atmospheric gas. These excited particles release light that is visible from Earth as a faint luminescence in the night...

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

Automated optical inspection (AOI) is a technology used in manufacturing processes, particularly in electronics, to automatically inspect and detect defects or anomalies in products. AOI systems use...

The coefficient termed by Callier as the ratio between the density of photographic negatives measured by parallel light and that measured by diffuse light, due to scattering effects. This effect is...

A particle that will not normally diffuse through animal or vegetable membrane. Larger than most inorganic compounds, colloids will remain suspended indefinitely.

In printing, a translucent screen used with lenses to provide an even distribution of diffused light.

The amount of x-rays used to penetrate and diffuse a target sample undergoing electron-probe microanalysis.

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.

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...

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

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...

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

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...

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...

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...

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...

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...

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 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...

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...

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

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...

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...

The simultaneous occurrence of specular and diffuse reflection.

The simultaneous occurrence of direct and diffuse transmission.

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...

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...

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