Obtaining of thermal images of small agricultural seed by techniques photoacoustic and photopyroelectric microscopy

A. Dominguez Pacheco1,2, C. Hernandez Aguilar1,2 and A. Cruz Orea2

1Instituto Politécnico Nacional - ESIME zacatenco, Mexico

Keywords: photothermal
property: thermal
material: seed

In this study, is carried out to observe which of the photothermal technique (FT) gives a better response in thermal imaging, in the case of small agricultural seeds by 1. Photoacoustic microscopy technique (PAM) and 2. Photopyroelectric Microscopy (PPEM). Experimental testing began with the placement of seeds within the cell of the PAM. In this case we used a tightly closed photoacoustic cell and the sensor was an electret microphone. The seeds were placed in the cell of the instrumentation with a pyroelectric sensor (PVDF 25/xm thickness), which is evenly covered with a homogeneous thin layer of thermal grease to ensure good thermal contact between the sensor and sample. PA and PPE cells were placed on a basis that makes a scan in the x-y axes by a system of motors. Scanning point to point of the sample, in both cases to a resolution 70 μ. Signal of cells PAM and PPEM are pre-amplified and then are sent to a lock-in amplifier. Using a personal computer controls the movement of the x-y axes, the data acquisition and recording, the data obtained are created photothermal images of seeds. We compared the thermal images obtained by both techniques, showing that PAM technique shows a higher quality thermal image. These details can be observed the difference in thermal properties of materials constituting of the seeds. The photothermal techniques allow the characterization of thermal parameters that have a importance relevant in the Agriculture.

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