Thermal Images of Small Agricultural Seeds Obtained by Photoacoustic and Photopyroelectric Microscopies

Abstract

Photoacoustic (PA) and photopyroelectric microscopies were used to obtain photothermal images of small agricultural seeds. In the photoacoustic microscopy (PAM) technique, a tightly closed PA cell was used with an electret microphone as the sensor. In photopyroelectric microscopy (PPEM), the seeds were placed in contact with a pyroelectric (PE) sensor. From the experimental data, it was possible to obtain thermal images of the scanned samples from the amplitude and phase signals. In the present research, thermal images of small agricultural seeds were obtained by both techniques and compared. The experimental results show that the photothermal images obtained by PAM have better resolution than those obtained by PPEM. PAM images using the amplitude signal appear to be more sensitive to detect seed structures as was observed in the seed thermal images obtained in this study.