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T. Okura
Once satisfactory calibration is established, the second step is implemented to
determine the specifications of the instrument hardware using this calibration data.
The NIR method is replaced if satisfactory results are not obtained after many trials.
10.3.2 The Second Step: Determining the Specification
Noise of various amplitudes is added to the acquired spectral data via simulations
and the calibrations are generated for each noise amplitude. The allowable noise
level can be determined based on the relationship between the noise amplitude and
calibration performance (R
2 , SEP and RPD). Other performance parameters such as
the wavelength resolution and wavelength accuracy can also be determined similarly.
The sampling optics should be decided in this step. Using experimental sampling
optics to determine the specification, the samples are measured to check whether the
optics generated the appropriate spectral shape for this application. It is important
to note that the purpose of the measurement is not just to obtain the correct spectral
shape but also to generate an appropriate spectral shape with good SNR, which in
turn provides good calibration for estimating the ingredients.
10.3.3 The Third Step: Manufacturing
The NIR instrument is designed according to the determined specification and manufactured. This process ensures the development of a NIR instrument with satisfactory
performance. Subsequently, the satisfactory calibration can be established using this
developed instrument.
10.4 Instrumental Differences
10.4.1 Effect of Instrumental Differences
The main application of NIR spectroscopy is not to study the molecular structure but
to measure the ingredients of a material. Therefore, many NIR instruments are being
employed at various sites for manufacturing or agriculture. Even when the same type
of instruments and same calibration are used, the measured ingredients differ due to
a phenomenon known as the instrumental difference.
In UV-VIS or infrared spectroscopy, the main purpose of the measurement is to
obtain the spectral waveform, and a small difference in the spectral shape does not
present a major problem. However, in NIR spectroscopy, a small subtle difference
T. Okura
Once satisfactory calibration is established, the second step is implemented to
determine the specifications of the instrument hardware using this calibration data.
The NIR method is replaced if satisfactory results are not obtained after many trials.
10.3.2 The Second Step: Determining the Specification
Noise of various amplitudes is added to the acquired spectral data via simulations
and the calibrations are generated for each noise amplitude. The allowable noise
level can be determined based on the relationship between the noise amplitude and
calibration performance (R
2 , SEP and RPD). Other performance parameters such as
the wavelength resolution and wavelength accuracy can also be determined similarly.
The sampling optics should be decided in this step. Using experimental sampling
optics to determine the specification, the samples are measured to check whether the
optics generated the appropriate spectral shape for this application. It is important
to note that the purpose of the measurement is not just to obtain the correct spectral
shape but also to generate an appropriate spectral shape with good SNR, which in
turn provides good calibration for estimating the ingredients.
10.3.3 The Third Step: Manufacturing
The NIR instrument is designed according to the determined specification and manufactured. This process ensures the development of a NIR instrument with satisfactory
performance. Subsequently, the satisfactory calibration can be established using this
developed instrument.
10.4 Instrumental Differences
10.4.1 Effect of Instrumental Differences
The main application of NIR spectroscopy is not to study the molecular structure but
to measure the ingredients of a material. Therefore, many NIR instruments are being
employed at various sites for manufacturing or agriculture. Even when the same type
of instruments and same calibration are used, the measured ingredients differ due to
a phenomenon known as the instrumental difference.
In UV-VIS or infrared spectroscopy, the main purpose of the measurement is to
obtain the spectral waveform, and a small difference in the spectral shape does not
present a major problem. However, in NIR spectroscopy, a small subtle difference