Bomem-GRAMS User's Guide

Appendix D
Glossary
infrared
A region of the electromagnetic spectrum between visible light and radio
waves where the wavelengths are longer than those of red light.
initial (or first) reference (or zero)
The first reference spectrum collected when the system was commissioned.
This is used as a base to monitor changes in the analyzer response over time.
Installation Qualification (IQ)
A procedure used to ensure that an instrument has been correctly installed.
interferogram
A representation of the electrical signal from the detector of a FT-IR
spectrometer. The interferogram is a graph of the voltage at the output of
the detector as a function of the position of interferometer scan mechanism.
The spectrum is calculated from the interferogram using a Fourier transform.
interferometer
The device in an FT-IR spectrometer that modulates the infrared beam
coming from the source.
The interferometer splits the infrared beam into two beams, introduces
a continuously varying optical path difference (OPD) between the two
beams, and recombines the beams. When the beams are recombined,
interference caused by the OPD modulates the beam.
least-squares regression
A regression procedure used to establish a parameter value derived from
multiple absorbance values such that the sum of the squares of
the differences between the model absorbances and the actual absorbances
is minimized.
a variety of media (e.g. wire pair, fiber, radio, etc.). MODBUS TCP/IP uses
TCP/IP and Ethernet to carry the MODBUS messages.
model (see calibration model)
52 Bomem-GRAMS User's Guide