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DX4040 INSTRUCTION AND OPERATING MANUAL (E2.04)
APPENDIX G: VOCABULARY
Absolute state of
charge
Relates to the capacity of a brand new battery and will therefore be reduced as the
battery is ageing.
Absorbance
A measure of the amount of infrared radiation absorbed by a sample gas as a
function of frequency.
Beam splitter
A component in the interferometer that reflects half of the infrared radiation and
transmits the other half.
Beer’s law
The law stating that the absorbance is linearly proportional to the concentration of
the gas (see page 17).
Detector
The component that measures the intensity of the infrared radiation and converts
this value into electrical signal.
Fourier transform
(FT)
The mathematical algorithm to get spectral data out of the interferogram. The
algorithm transforms the intensity as a function of time values to intensity as a
function of wavelength.
Infrared (IR)
Electromagnetic radiation that has wavelengths ranging from 0.75
µ
m to 1000
µ
m
(14000 – 10 cm
-1
).
Interferogram
The measured intensity as a function of optical path length difference
Interferometer
The device that produces interference signal of the infrared radiation.
Noise
Detected signals that do not come from the sources that we actually want to
measure.
Reference
spectrum
A spectrum that is used as a known reference when determining the
concentrations of unknown gas components.
Relative state of
charge
Relates to the last full cycle and will therefore show 100 % when fully charged.
Resolution
The degree to which different frequencies can be distinguished from each other.
Signal-to-noise
ratio (SNR)
The ratio of the amplitude of the actual measured signal to the amplitude of the
noise at the same point.
Spectrum
A graph that shows the transmission of the infrared radiation through the gas as a
function of wavelength
Transmittance
The ratio of the infrared radiation transmitted through the sample gas to the
amount of the infrared radiation entering the sample gas.
Wavelength
Another form of expressing the frequency of the infrared radiation: the distance
between two peaks in the oscillation.
Wave number
Number of wavelengths in a centimeter. For example, if the wavelength is 10
µ
m,
the corresponding wave number is 1000 cm-1.
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