Chapter 11
Time-of-Flight Spectroscopy
Tetsuya Inagaki and Satoru Tsuchikawa
Abstract This chapter summarizes the principle and application of time-of-flight
(TOF) NIR spectroscopy, which can evaluate the contribution of scattering and
absorption of light in samples simultaneously. In order to construct robust calibrations
for organic materials by NIR spectroscopy, it is important to evaluate and understand
the spectral contribution from light absorption (absorption resulting from harmonics
or overtones of the fundamental absorptions of molecular vibrations) and light scattering (mainly due to the cellular structure). In this chapter, we introduce the principle
of TOF-NIR spectroscopy and some applications to agricultural, medical area, and
forest products.
Keywords Time-resolved spectroscopy · Time-of-flight spectroscopy · Spatially
resolved spectroscopy · Absorption coefficient · Reduced scattering coefficient
11.1 Introduction
In the past three decades, many researchers have paid attention to the potential use
of NIR spectroscopy as a practical use for the detection of organic compounds in
materials. In fields such as agriculture, food, pharmaceuticals, medical, paper, and
polymers, there is a strong interest in NIR spectroscopy because of its nondestructiveness, accuracy, quick measurement, and easy operation. The measurement of
NIR spectra (i.e., detection of NIR light from the sample) is done by transmittance
(including interactance) or diffuse reflectance mode. The transmission method is
desirable for detecting internal information in large quantities of material, although
the optical information from the diffuse reflectance spectrum is limited to the surface
of the sample. It is particularly important to proceed with the development of NIR
transmission devices for detecting the internal properties of high moisture fruits,
vegetable products, or thick wood products.
T. Inagaki (B) · S. Tsuchikawa
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
e-mail: inatetsu@agr.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ozaki et al. (eds.), Near-Infrared Spectroscopy,
https://doi.org/10.1007/978-981-15-8648-4_11
265
Time-of-Flight Spectroscopy
Tetsuya Inagaki and Satoru Tsuchikawa
Abstract This chapter summarizes the principle and application of time-of-flight
(TOF) NIR spectroscopy, which can evaluate the contribution of scattering and
absorption of light in samples simultaneously. In order to construct robust calibrations
for organic materials by NIR spectroscopy, it is important to evaluate and understand
the spectral contribution from light absorption (absorption resulting from harmonics
or overtones of the fundamental absorptions of molecular vibrations) and light scattering (mainly due to the cellular structure). In this chapter, we introduce the principle
of TOF-NIR spectroscopy and some applications to agricultural, medical area, and
forest products.
Keywords Time-resolved spectroscopy · Time-of-flight spectroscopy · Spatially
resolved spectroscopy · Absorption coefficient · Reduced scattering coefficient
11.1 Introduction
In the past three decades, many researchers have paid attention to the potential use
of NIR spectroscopy as a practical use for the detection of organic compounds in
materials. In fields such as agriculture, food, pharmaceuticals, medical, paper, and
polymers, there is a strong interest in NIR spectroscopy because of its nondestructiveness, accuracy, quick measurement, and easy operation. The measurement of
NIR spectra (i.e., detection of NIR light from the sample) is done by transmittance
(including interactance) or diffuse reflectance mode. The transmission method is
desirable for detecting internal information in large quantities of material, although
the optical information from the diffuse reflectance spectrum is limited to the surface
of the sample. It is particularly important to proceed with the development of NIR
transmission devices for detecting the internal properties of high moisture fruits,
vegetable products, or thick wood products.
T. Inagaki (B) · S. Tsuchikawa
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
e-mail: inatetsu@agr.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ozaki et al. (eds.), Near-Infrared Spectroscopy,
https://doi.org/10.1007/978-981-15-8648-4_11
265