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Insight in the transmission of laser light through intact fruit is important to understand and optimize the signals acquired with laser-based spectroscopy methods such as gas in scattering media absorption spectroscopy (GASMAS), which is based on tunable diode laser absorption spectroscopy (TDLAS). To this end, we quantified the bulk optical properties (BOP) of the different tissue layers (epidermis, outer cortex, inner cortex, and core) of Conference pear (Pyrus communis) samples using double integrating spheres measurements. A clear chlorophyll-a absorption feature was observed in the bulk absorption coefficient (μa) at 690 nm for the epidermis samples. At 761 nm, the bulk scattering coefficient (μs) decreased from the epidermis (256 ± 30.4 cm-1) towards the core (149 ± 12 cm-1) region where the difference between the cortex tissues and core was found to be negligible. The observed anisotropy factor (g) of the epidermis was lower than those of the other tissue layers (0.81 ± 0.026 vs. 0.94 ± 0.01). Next, Monte Carlo voxelized media (MCVM) simulations were performed based on these BOP values. As expected according to the Lambert-Beer law, the transmittance through the pear tissues increased exponentially for linearly decreasing layer thickness. Finally, these simulations were compared to transmittance measurements on pears using a GASMAS O2 sensor (operating at 761 nm), where the sample thickness was reduced by sequentially slicing the pear from the epidermis towards the center. It was found that the simulated transmittance based on the measured BOP followed the same trend as a function of the fruit thickness as the measured GASMAS transmittance. Therefore, these simulations can contribute to the optimization of the measurement configuration for O2 monitoring in intact pear fruit with GASMAS.
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