
SpectralLED® RS-7 USER MANUAL
Page 75
forward biased.
Light
Electromagnetic radiant energy that is visually detectable by the normal human
observer, radiant energy having wavelengths from about 380 nm to about 780 nm.
Linearity
Refers to a mathematical relationship or function that graphically represents as a
straight line, as in two quantities that are directly proportional to each other, such
as voltage and current in an RLC circuit, or the mass and weight of an object.
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of
light travelling in a given direction. It describes the amount of light passes through
is emitted or reflected from a particular area, and falls within a given solid angle.
The SI unit for luminance is candela per square meter (cd/m
2
).
LUX (lx)
Lux: Illuminance corresponding to a luminous flux density of one lumen per square
meter. SI unit of illuminance.
Menu
A set of commands, parameters, or submenus grouped in a pop down menu listed
in the menu bar. A pop down menu displays when it selects from the menu bar by
using a mouse, the key letter, or the cursor keys and <Enter>.
A list of options within a program activate routines at the time of selection.
Menu Bar: The bar at the top of the screen that lists the pop down menus that are
available.
Mode
Identifies the type of data in a file (i.e. Reflectance, Transmittance, other).
nm
Nanometer: Unit of length equal to 10-9 meters commonly used for identifying
wavelengths of the visible portion of the electromagnetic spectrum.
NIST
U. S. National Institute of Standards and Technology
nits
In lighting, the nit is a unit of visible-light intensity, commonly used to specify the
brightness of a cathode ray tube or liquid crystal display computer display. One nit
is equivalent to one candela per square meter.
Optical Geometry
Geometrical optics, or ray optics, describes light propagation in terms of rays. The
ray in geometric optics is an abstraction, or instrument, useful in approximating
the paths along which light propagates in certain classes of circumstances.
Optical Reference Tool
The technique of establishing precise reference lines and planes by means of
telescopic sights, especially for aligning machinery, machine-shop work.
Photodiode
A photodiode is a semiconductor device that converts light into current. The
current generates when photons are absorbed in the photodiode. A small amount
of current also produces when no light is present. Photodiodes may contain optical
filters, built-in lenses, and may have large or small surface areas.
Photometric
Pertaining to the measurement of the intensity of light.
Radiance
Radiant power per unit source area per unit solid angle. Usually expressed in
watts*m
-2
*steradian
-1
(watts per steradian per meter squared).
Radiometer
Processes the signals emitted by the detector into a linear form.
Radiometric
Pertaining to the measurement of radiation (optical power).
Root-mean Square (RMS) The square root of the arithmetic mean of the squares of a set of values, used as a
measure of the typical magnitude of a set of numbers, regardless of their sign.