BUCHI NIRMaste Pro IP65 - Manual (Page 17)

4 Description of function
17 NIRMaster Operation Manual, Version B
Data processing and interferogram analysis
The NIR light interacts with the sample G material in different ways, leaving a characteristical finger-
print on the interferogram. At liquids the light is mostly transmitted and at solids reflected. The
remaining light is collected by the detector H. The built-in computer further processes the raw signal.
Process steps Result
Signal preprocessing Interferogram
Fourier transformation Raw spectrum
Signal background correction Spectrum of sample
Chemometric analysis of the spectral data Sample analysis
Display of the result via NIRWare Operator on the attached monitor Sample analysis is displayed
4 .2 Measurement modes and setups
At the NIRMaster, different measurement setups can easily be attached to the basic intrument to meet
the individual sample requirements. To choose the best setup for a specific range of samples the
optical properties of the sample material must be known.
Mode overview and application
Sample characteristics (for NIR light) Section Measurement setup Typical application
Diffuse reflection 4.2.1 Adequate sample cup Predominantly non-translucent solids
such as powders, pellets and cereals
Transflectance 4.2.2 Sample cup / petri dish+
matching transflectance cover Liquids with weak diffuse reflection and
medium transmission rate characteristics
(e.g. transparent to opaque liquids)
4 .2 .1 Diffuse reflection mode
Most non-translucent materials (e.g. solids such as powders, pellets and cereals) can be analyzed
via diffuse reflection. The NIR light penetration is limited by the sample material. It interacts with the
sample, is refracted and diffusely reflected into the sensor. The reflected rays contain the spectral
information of the sample.
Sensor
NIR light
Sample material