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PI Physik Instrumente - Semiconductor Applications 5/24 ROS LB
luminance Dictionary Terms

luminance factor
Ratio of the luminance of a specimen to that of a perfect reflecting or transmitting diffuser identically illuminated.
cascade method
A heterochromatic photometric process using successive comparison of similar chromaticities and the calculation of relative...
equiluminous colors
Colors differing only in chromaticity but not in luminance.
cosine law of illumination
Law relating the illuminance (or irradiance) of a surface to the cosine of the angle, q, between the normal to the surface...
apostilb
A unit of luminance equal to 1/p candela per square meter.
sine wave testing chart
A test chart whose luminance changes uniformly in one direction according to a sinusoidal rule. These charts carry groups of...
microphotometer
An instrument capable of measuring the transmitted or reflected luminance from a very small area seen under a microscope....
nit
Unit of measurement of brightness (luminance) equal to one candela per square meter.
footcandle
Unit of illuminance equal to one lumen per square foot. (fc).
negative glow
In a cold-cathode tube, the luminance between the cathode dark space and the Faraday dark space. In a vacuum tube, the...
photometric equipment
Photocells of various kinds used to measure photometric quantities; i.e., intensity, luminance and illuminance. Meter...
photometric cube
A prism used in a photometer for the adjacent comparison of separate luminance.
vignetting
In an optical system, the gradual reduction of image illuminance as the off-axis angle increases, resulting from limitations...
highlight
The portion of a reproduced image having the greatest luminance.
lux
SI unit of luminous incidence or illuminance, equal to 1 lumen per square meter.
Liebmann effect
The visual perception of contrasting forms is more difficult if the forms have the same luminance but different...
receiver primaries
Also known as display primaries. Colors formed by a television receiver that are of constant chromaticity and variable...
luminance meter
A type of photometer calibrated in luminance units (candles per square unit, or lamberts). In photography an exposure meter...
Strehl ratio
The ratio of the illuminance at the peak of the diffraction pattern of an aberrated point image to that at the peak of an...
luma
The luminance portion of a composite video signal, i.e., the portion of the signal that corresponds to the brightness of the...
photochromatic interval
The discrepancy between the absolute luminance threshold and the photochromatic threshold.
absolute luminance threshold
The minimum value of luminance for vision. The value may vary with age as well as dark adaption period. (Measured range...
dark discharge
In a gas, an electrical discharge that has no luminance.
scotopic vision
Vision by means of retinal rods; vision of the dark-adapted eye. In scotopic vision, the level of luminance is so low that...
photopic vision
Vision by means of retinal cones; color vision. Relatively high levels of luminance are required for photopic vision.
lambert
A unit of luminance equal to 1/p candela per square centimeter. (l).
sine wave object
An object that has a sinusoidal variation of luminance. Its image will have a sinusoidal variation of illuminance and the...
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...
flicker photometry
Heterochromatic photometry that depends on the elimination of chromatic flicker at a lower frequency than luminance flicker.
Craik-O'Brien effect
Observed when alterations in the luminous sterance at the contour of an object create the illusion of the outer zones...
Fechner ratio
The differential luminance threshold divided by the luminance.
troland
That level of retinal illuminance resulting when a surface with a luminance of 1 candela/m2 is viewed through a pupil with...
additivity of luminance
The luminance of a mixture of lights is the sum of the luminances of the component lights in the mixture.
nox
Equal to 10-3 lux; used in measuring low values of illumination and luminance.
binocular threshold
The absolute luminance threshold for detection by the two eyes.
inverse square law
The law stating that the illuminance (or irradiance) from a point source varies as the inverse square of the distance...
apparent luminance
The perceived brightness of an object being viewed at some distance, especially through an optical instrument.
atmospheric attenuation
The reduction in luminance of a light beam due to absorption and scattering as it passes through the atmosphere.
background luminance
The intensity of the light in the scene behind an object being viewed.
colorimetric purity
Ratio, to the luminance of a test color, of the luminance of the spectrum color that matches the test color when mixed with...
comb filter
A filter that passes a series of wavelength regions that are at equal distances from one another, such that its output...
illuminance
Luminous flux incident per unit area of a surface; luminous incidence. (The use of the term "illumination" for...
lambertian surface
A perfectly diffusing surface; the intensity of the light emanating in a given direction from any small surface component is...
chrominance
The difference between any color and a reference color having equal luminance and a specified chromaticity.
composite video
A type of video signal in which the luminance and chrominance portions of the signal, or the luma and chroma, have been...
stilb
A unit of luminance that is equal to one candela/cm2. (sb).
high-gain screen
A screen with a reflected or transmitted light beam that is confined to a much smaller bundle than was received by the...
uniform luminance area
In a cathode-ray tube, the region wherein a display on the tube keeps 70 percent or more of its luminance at the center of...
luminance range
An objective measure of an object's brightness that is derived from the ratio of the luminance of its lightest section to...
illumination
The general term for the application of light to a subject. It should not be used in place of the specific quantity...
image brightness
The apparent luminance of the image as seen through an optical system. This brightness of the image is determined by the...
luminance
Luminous flux emitted from a surface per unit solid angle per unit of area, projected onto a plane normal to the direction...
etendue
A product of the area of a light beam (normal to its direction of propagation) and the solid angle that the beam includes;...
telephotometer
An instrument used to measure the luminance (brightness) of a distant object. The object is viewed through a small...
footlambert
Unit of luminance equal to 1/p candela per square foot. (fl).
cathode dark space
The area of low-level luminance lying between the cathode and the negative glow in a glow-discharge, cold-cathode tube.
heterochromatic photometry
Light measurement by comparison of the luminances of unlike chromaticities.
Ferry-Porter law
The law stating that the critical fusion frequency is approximately proportional to the logarithm of the luminance and the...
photometer
A device used to compare the luminous intensities of two sources by comparing the illuminance they produce.
contrast
The apparent difference in brightness between light and dark areas of an image. For a light target against a dark...
photographic exposure
The product of exposure time and irradiance or illuminance.
constant luminance encoder
A device used in broadcast CCD cameras to improve definition in heavily saturated colors by band-limiting the color...
mesopic vision
Vision at intermediate levels of luminance between photopic and scotopic vision, where both retinal cones and retinal rods...
photon counter
A device used to evaluate the luminance of a surface by determining the number of photons emitted from a sample surface area.
visual photometer
A photometer that permits visual comparison of the luminance of two surfaces.
brightness meter
An instrument for measuring the brightness (luminance) of a scene. It may be a spot meter, covering an area of a degree or...

(66 results found)

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