研究目的
To determine the efficiency of the continuous wave terahertz imaging method to detect infestations caused by insects in wheat kernels.
研究成果
THz imaging is efficient for detecting insect infestations in grain, with absorbance highest in un-infested kernels and decreasing at later growth stages. The method allows visualization of infestation location and size, and the defined coefficients (SC and IC) effectively quantify infestation severity, which increases with larval growth. Further research is needed to expand applicability.
研究不足
The study is limited to one insect species (Sitophilus zeamais) and wheat kernels; further work is needed to broaden the basis to other insect species and grain types. The technology requires exploration in realistic applications, and factors like sample variety, condition, interference, and scattering may influence results.
1：Experimental Design and Method Selection:
A continuous wave terahertz imaging system was designed to record THz images for different life stages of insect infestations in wheat kernels. The method involved using a CO2 laser-pumped THz laser as the light source and a pyroelectric camera as the detector, with image analysis using thresholding procedures to segment images into satiation, infested, and surrounding regions.
2：Sample Selection and Data Sources:
Wheat kernels infested by Sitophilus zeamais were prepared by artificial implantation of insect eggs in the germ. Samples were incubated at 30°C and 70% RH, and kernels were removed at different time intervals (e.g., 10, 20, 30, 40, 50 days) to represent different life stages (larval, pupal, adult).
3：List of Experimental Equipment and Materials:
Equipment included a CO2 laser-pumped THz laser (SIFIR-50 from Coherent Inc), a pyroelectric camera (Pyrocam III), Picarin lenses, a two-dimensional platform with a stepper motor, and a computer for control and data analysis. Materials included wheat kernels and Sitophilus zeamais insects.
4：Experimental Procedures and Operational Workflow:
The THz laser emitted continuous wave at 2.52 THz with 30 mW output power. Single kernels were placed on the platform, and THz images were acquired. The software controlled the platform movement and stored images. Images were analyzed by segmenting based on red and blue component thresholds (TR=204, TB=204) to calculate satiation and infestation coefficients.
5：52 THz with 30 mW output power. Single kernels were placed on the platform, and THz images were acquired. The software controlled the platform movement and stored images. Images were analyzed by segmenting based on red and blue component thresholds (TR=204, TB=204) to calculate satiation and infestation coefficients.
Data Analysis Methods:
5. Data Analysis Methods: THz pseudo-color images were segmented into regions (R0 for satiation, R1 for infested, R2 for surrounding) using thresholding. Coefficients SC (N0/N2) and IC (N1/N2) were defined and calculated to quantify infestation levels. Data was analyzed to observe trends in absorbance and infestation degree over time.
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