11 Time-of-Flight Spectroscopy
273
Fig. 11.2 Light propagation in a agathis, b yellow poplar, and c rubber wood simulated by the
Monte Carlo method
For the SR technique, the point light source is generally injected on sample and the
spatial distribution surrounding the injected light is detected by optical fiber arrays
or non-contact reflectance image, which can be implemented with fiber optic probe,
monochromatic imaging, and hyperspectral imaging. Measured spatial distributions
were fitted by the analytical equation derived by Farrell et al. [17] with an appropriate
inverse algorithm.
11.8 New Measurement System Minimizing the Effect
of Light Scattering.
It can be extremely difficult to obtain reliable calibrations with highly scattering
medium by conventional NIR spectrometer if both of the scattering and absorption
properties of the samples vary. For example, variations of light scattering with size
or concentration of rubber particles in latex samples are complicate. The variation of
scattering properties in sample makes it difficult to interpret the quantitative analyses
and to construct linear calibrations (multiple linear regression, principal component
regression, and partial least squares regression). Shimomura et al. established threefiber-based diffuse reflectance spectroscopy (TFDRS) based on spatially resolved
spectroscopy to estimate the sugar content in fruits or total hemoglobin concentration
and tissue oxygen saturation in human tissues using wavelengths range of 800 nm
to 1100 nm [18–20]. A geometry of the TFDR spectrometer is shown in Fig. 11.3.
A continuous wave laser beam is emitted into the sample through an optical fiber.
273
Fig. 11.2 Light propagation in a agathis, b yellow poplar, and c rubber wood simulated by the
Monte Carlo method
For the SR technique, the point light source is generally injected on sample and the
spatial distribution surrounding the injected light is detected by optical fiber arrays
or non-contact reflectance image, which can be implemented with fiber optic probe,
monochromatic imaging, and hyperspectral imaging. Measured spatial distributions
were fitted by the analytical equation derived by Farrell et al. [17] with an appropriate
inverse algorithm.
11.8 New Measurement System Minimizing the Effect
of Light Scattering.
It can be extremely difficult to obtain reliable calibrations with highly scattering
medium by conventional NIR spectrometer if both of the scattering and absorption
properties of the samples vary. For example, variations of light scattering with size
or concentration of rubber particles in latex samples are complicate. The variation of
scattering properties in sample makes it difficult to interpret the quantitative analyses
and to construct linear calibrations (multiple linear regression, principal component
regression, and partial least squares regression). Shimomura et al. established threefiber-based diffuse reflectance spectroscopy (TFDRS) based on spatially resolved
spectroscopy to estimate the sugar content in fruits or total hemoglobin concentration
and tissue oxygen saturation in human tissues using wavelengths range of 800 nm
to 1100 nm [18–20]. A geometry of the TFDR spectrometer is shown in Fig. 11.3.
A continuous wave laser beam is emitted into the sample through an optical fiber.