16:15 〜 16:30
▲ [16p-418-12] Evaluation of freshness Japanese San Fuji apples – comparison of Biospeckle and Optical coherence tomography measurements
キーワード：Spectral domain OCT, Biospeckle, non-invasive
In this paper, we have applied non-invasive optical methods based on biospeckles for evaluation of freshness of Japanese SanFuji apples. Biospeckles are formed when a biological tissue is illuminated by monochromatic light due to scattering by organelles moving within the tissue. We have employed Optical Coherence Tomography and Speckle imaging for evaluation supplemented by thermal camera and smell measurements. In both of the methods based on biospeckles, correlation of a frame by frame analysis was used for evaluation of freshness.
Apples were purchased from a single dealer and they were spaced every five days starting from November 4 till December 20. All the apples were stored at room temperature of 21deg C.
The system with a CMOS camera (1024x1280 pixels) was used for speckle imaging. A total of 300 speckle images binned to 240 x320 pixels sampled at the rate of 15fps were obtained over a period of 14 sec. A total of three apples with three different points for each apple were measured at every 5th over a period of month. Next speckle images were characterized offline using by different parameters of cross-correlation between the neighboring frames, co-occurrence matrix and speckle contrast. Based on the analysis, a significant broadening could be seen in the correlation and the co-occurrence matrix with increasing storage.
A spectral domain OCT (SD-OCT) system using a superluminescent diode (SLD) centered at wavelength 836.1 nm and a bandwidth of 55.2 nm containing a line scan CCD camera (L104k-2k, BASLER, Germany) with 2048 pixels was used. The axial and lateral resolutions of the OCT system were estimated to be 6 μm and 22 μm, respectively. The spectral imaging data were acquired through an image grabber while laterally scanning the sample surface by galvano mirrors. In order to obtain biospeckles, hundred speckle frames (2048x1024) from a single lateral position was continuously acquired at every 500ms. In order to characterize the freshness, autocorrelation was calculated and correlation length as a function of position along depth revealed that recent one was found to have higher correlation in deeper region.
Preliminary experiments done using laser biospeckles with apples revealed that correlation measures reflect the freshness of the apple. The measures were also correlated with results obtained using thermal camera images and weight and smell measurements. However, the physiological origin for differences in the biospeckles remains to be investigated.
Apples were purchased from a single dealer and they were spaced every five days starting from November 4 till December 20. All the apples were stored at room temperature of 21deg C.
The system with a CMOS camera (1024x1280 pixels) was used for speckle imaging. A total of 300 speckle images binned to 240 x320 pixels sampled at the rate of 15fps were obtained over a period of 14 sec. A total of three apples with three different points for each apple were measured at every 5th over a period of month. Next speckle images were characterized offline using by different parameters of cross-correlation between the neighboring frames, co-occurrence matrix and speckle contrast. Based on the analysis, a significant broadening could be seen in the correlation and the co-occurrence matrix with increasing storage.
A spectral domain OCT (SD-OCT) system using a superluminescent diode (SLD) centered at wavelength 836.1 nm and a bandwidth of 55.2 nm containing a line scan CCD camera (L104k-2k, BASLER, Germany) with 2048 pixels was used. The axial and lateral resolutions of the OCT system were estimated to be 6 μm and 22 μm, respectively. The spectral imaging data were acquired through an image grabber while laterally scanning the sample surface by galvano mirrors. In order to obtain biospeckles, hundred speckle frames (2048x1024) from a single lateral position was continuously acquired at every 500ms. In order to characterize the freshness, autocorrelation was calculated and correlation length as a function of position along depth revealed that recent one was found to have higher correlation in deeper region.
Preliminary experiments done using laser biospeckles with apples revealed that correlation measures reflect the freshness of the apple. The measures were also correlated with results obtained using thermal camera images and weight and smell measurements. However, the physiological origin for differences in the biospeckles remains to be investigated.