Description

Visible/near infrared reflectance (VIS/NIR) spectroscopy can be a nondestructive, instrumental method for fast, accurate, and precise evaluation of the chemical composition of agricultural materials. Each major organic component in agricultural materials has absorption characteristics (due to vibrations arising from the stretching and bending of H bonds associated with C, O, and N) in the near infrared region that are specific to the components. These absorption characteristics primarily determine diffuse reflectance, which gives us the means for assessing composition. While the VIS range gives us the spectral characteristics of bonding electrons and mainly the color differences between materials. VIS/NIR spectroscopic techniques have very high signal-to-noise ratio, short detector response time, and can simultaneously determine multiple constituents in the tested material.

The existing spectral imaging system at UGA is based on Liquid Crystal Tunable Filters (LCTFs). We have matching fiber-optic spectrometers, LCTFs and video cameras to cover the range from 400 nm to 1100 nm (640x480 pixels), and from 1000 to 1700 nm (300x240 pixels), both at 8-bit analog or 10-bit digital. Although our imaging system can be transported to greenhouses or fields as needed, it can only acquire quality spectral images of static objects, because of the relatively slow wavelength switching speed of LCTFs. We also have broad-beam UV light sources that can be used for fluorescence imaging of whole plant canopies.

Projects

Multi-spectral imaging projects (previous and current):
Bush Bean plants grown under different nitrogen treatments.
Bahia Grass plants grown under different zinc and copper treatments.
Pine seedlings grown under different zinc and copper treatments.
Spectral characterization of weevil-infested pecan bits.

Planned projects:
Tomato Spotted Wilt (TSW) virus effects in Peanut plants.
Steady-State Fluorescence Imaging for water and disease stresses.

Contact Info

Chi N. Thai
Associate Professor
Phone: (706) 542-1130
Fax: (706) 542-8806
(thai@engr.uga.edu)

The University of Georgia Department of Biological and Agricultural Engineering.
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