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Bruker Optik GmbH IFS 125M User Manual
Glossary F
Signal-to-noise
ratio
The signal-to-noise ratio describes the quality of a wanted sig-
nal which has been superimposed by noise. It outlines the ratio
between the average performance of a wanted signal emitted
by a signal source, and the average performance of noise.
Source In the mid and near infrared an IR source is used which emits
infrared light.
Spectrometer Spectrometer derives from the Latin word specere meaning
image, and the Greek word metron meaning to measure. A
spectrometer uses some sort of mechanical or electrical detec
-
tion device to obtain the infrared spectrum of a sample. It con-
tains a source of infrared radiation, a sample compartment to
allow the radiation to interact with a sample, a detector for radi
-
ation, and units to determine and display the intensity of radia-
tion.
Spectrum A spectrum is an image of radiation energy dispersed into its
wavelength constituents or a two-dimensional plot of radiation
energy, or radiation energy ratio versus wavelength. It includes
a set of absorption, reflection or transmission values which
have been measured by an IR spectrometer based on defined
wavelengths.
The features in an infrared spectrum correlate with the pres-
ence of functional groups of molecules of a sample.
Subnet mask The subnet mask is a network mask used to partition network
addresses for efficiency and security. Subnet masks work by
’masking’ less significant address bits on all workstations in the
sub-network.
Transmission Transmission describes the portion of transmitted infrared light.
One part of the incidented light directly passes through the
sample without any interactions with electrons or molecules in
the sample. Another part of light is absorbed and continuously
re-emitted to the same direction from which the incident light
comes.
Transmittance Transmittance is the ratio between the beam energy transmit-
ted through a sample and the beam energy incident on the sur-
face of the sample.
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