8 New Trend in Instrumentation of NIR Spectroscopy …
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Fig. 8.5 Miniaturization of NIR spectrometers
8.2 The Principles of the Technology Underlying
Miniaturized NIR Spectroscopy
The design of handheld NIR spectrometers mostly deciding about their working
characteristics is the detector and monochromating (i.e., wavelength selection) technology [6]. There is much less variety in the technology used for light sources here,
although certain notes need to be made below.
8.2.1 Light Sources
In general, there exist two types of light sources in commercially available miniaturized spectrometers. Most devices employ the conventional principle of tungsten light bulb (e.g., microPHAZIR, MicroNIR), although adopted for the needs
of highly autonomous spectrometers. This primarily involves optimizations toward
low power consumption. To maintain control over the thermal stability and output of
these sources, manufacturers often recommend to perform frequent reference scans,
which are not problematic as these devices often rapid scanning. Another used technology are light emitting diodes (LEDs). Semiconductor-based sources offer unparalleled power effectiveness, affordability, and compact dimensions. However, they
suffer from narrow emission spectrum, which makes such sensors practically useful
mostly in Vis/SW-NIR region (e.g., SCiO device).
199
Fig. 8.5 Miniaturization of NIR spectrometers
8.2 The Principles of the Technology Underlying
Miniaturized NIR Spectroscopy
The design of handheld NIR spectrometers mostly deciding about their working
characteristics is the detector and monochromating (i.e., wavelength selection) technology [6]. There is much less variety in the technology used for light sources here,
although certain notes need to be made below.
8.2.1 Light Sources
In general, there exist two types of light sources in commercially available miniaturized spectrometers. Most devices employ the conventional principle of tungsten light bulb (e.g., microPHAZIR, MicroNIR), although adopted for the needs
of highly autonomous spectrometers. This primarily involves optimizations toward
low power consumption. To maintain control over the thermal stability and output of
these sources, manufacturers often recommend to perform frequent reference scans,
which are not problematic as these devices often rapid scanning. Another used technology are light emitting diodes (LEDs). Semiconductor-based sources offer unparalleled power effectiveness, affordability, and compact dimensions. However, they
suffer from narrow emission spectrum, which makes such sensors practically useful
mostly in Vis/SW-NIR region (e.g., SCiO device).