|KISTLER, ROSS - University Of Maryland|
|GADSDEN, ANDREW - University Of Maryland|
Submitted to: Applied Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2016
Publication Date: 12/22/2016
Citation: Lefcourt, A.M., Kistler, R., Gadsden, A., Kim, M.S. 2016. Automated cart with VIS/NIR hyperspectral reflectance and fluorescence imaging capabilities. Applied Sciences. 7(1):3.
Interpretive Summary: Described is the design and testing of a system that includes an automated cart and an optical system for taking images at discrete visible wavelengths. The system also includes a pulsed UV laser that allows imaging of fluorescent responses regardless of ambient sunlight. The system was designed to be able to detect small quantities of contaminants such as fecal materials in fields and, more specifically, in agricultural produce fields. Fecal contamination in produce fields is a recognized food safety concern. Current industry practice is to survey fields by eye prior to harvest and to exclude identified problem areas from harvest. One possible use of the cart and imaging system presented in this study would be to test the feasibility of using imaging techniques to supplement the existing survey protocols. An ancillary goal would be to determine the most cost-effective method and technique that could be used for development of a commercial imaging system for surveying fields. This manuscript will be of interest to food safety scientists, agricultural equipment manufacturers, food production companies, and farmers.
Technical Abstract: A system to take high-resolution VIS/NIR hyperspectral reflectance and fluorescence images in outdoor fields using ambient lighting or a pulsed laser (355 nm), respectively, for illumination was designed, built, and tested. Components of the system include a semi-autonomous cart, a gated-intensified camera, a spectral adapter, a frequency-triple Nd:YAG laser, and optics to convert the Gaussian laser beam into a line-illumination source. The front wheels of the cart are independently powered by stepper motors that support stepping or continuous motion. When stepping, a spreadsheet is used to program parameters of image sets to be acquired at each step. For example, the spreadsheet can be used to set delays before the start of image acquisitions, acquisition times, and laser attenuation. One possible use of this functionality would be to establish acquisition parameters to facilitate measurement of fluorescence decay-curve characteristics. The laser and camera are mounted on an aluminum plate that allows the optics to be calibrated in a laboratory setting and then moved to the cart. The system was validated by acquiring images of fluorescence responses of spinach leaves and dairy manure using a step size of 2.5 mm and an optical resolution of 1.5 mm/pixel.