Simultaneous acquisition of fluorescence and reflectance imaging techniques with a single imaging device for multitask inspection
Inventors
Kim, Moon S. • Chen, Yud Ren • Chao, Kuanglin • Lefcourt, Alan M.
Assignees
US Department of Agriculture USDA
Publication Number
US-7787111-B2
Publication Date
2010-08-31
Expiration Date
2028-04-25
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Abstract
A hyperspectral reflectance and fluorescence line-scan imaging system is used for on-line quality and safety inspection of agricultural commodities. The system simultaneously acquires hyperspectral/multispectral combinations of both fluorescence and reflectance images of the agricultural commodities.
Core Innovation
The invention provides an online line-scan imaging system capable of simultaneously acquiring a combination of hyperspectral/multispectral reflectance and fluorescence images of an object, such as agricultural commodities, using a single image acquisition device, for example a Charge Coupled Device (CCD). This system can capture both reflectance and fluorescence image data simultaneously at selected spectral wavebands, with illumination appropriate for each imaging method, and with wavelengths selectable by software reconfiguration.
The problem addressed is the need for rapid, online quality and safety inspection of agricultural commodities, specifically for detecting defects and fecal contamination, which have been difficult to achieve with existing systems. Current commercial sorting systems are typically dedicated to single tasks like size, shape, or color sorting, requiring multiple systems or multiple imagers to detect defects, contamination, and quality attributes concurrently. There is no existing online inspection system that simultaneously differentiates fecal contamination and defects using combined fluorescence and reflectance imaging with a single imaging device.
The invention solves this by providing a hyperspectral reflectance and fluorescence line-scan imaging system that can fuse multispectral parameters from fluorescence and reflectance methods to simultaneously detect multiple characteristics or artifacts, including defects, shape, size, color, color variations, and fecal contamination. It includes specific components such as an Electron Multiplying Charged-Couple-Device (EMCCD), a line-scan spectrograph, lens assemblies, and a lighting system with a filtered quartz-tungsten halogen lamp and a micro discharge lamp for UV excitation. This configuration enables rapid, real-time, automated inspection compatible with production line speeds and allows on-the-fly wavelength selection purely via software without mechanical alterations.
Claims Coverage
The patent includes multiple independent claims covering an imaging system and a method for simultaneously acquiring hyperspectral/multispectral reflectance and fluorescence images using a single CCD device.
Simultaneous image acquisition with a single CCD
The imaging system simultaneously captures both fluorescence and reflectance images of an object using a single charge coupled device (CCD) and a spectrograph while the object is illuminated by both a reflectance lamp and ultraviolet light, allowing concurrent processing of fluorescence and reflectance data.
Use of an electron multiplying CCD and specific optical components
The system employs an electron multiplying CCD, a dispersive line-scan spectrograph, a lens assembly including a c-mount lens, and ultraviolet blocking filters positioned to block specific wavelengths to optimize imaging.
Combined illumination sources with filtering
The system uses a quartz-tungsten halogen lamp with a long pass filter for reflectance illumination and a micro discharge high-intensity UV lamp for fluorescence excitation, enabling simultaneous fluorescence capture between 400 nm and 700 nm and reflectance capture between 700 nm and 1000 nm.
Software selectable spectral bands and integration with sorting machines
Wavelengths for fluorescence and reflectance image acquisition can be selected on-the-fly using software, and the imaging system is operatively connected to a sorting machine that makes sorting decisions based on processed image data from the system.
Method of simultaneous hyperspectral/multispectral image capture
A method involving providing a CCD and data processing unit with a spectrograph, illuminating selected objects simultaneously with a reflectance lamp and ultraviolet light, capturing images via the spectrograph on the CCD, and processing fluorescence and reflectance data concurrently for inspection and sorting purposes.
The claims cover an integrated imaging system and method enabling rapid, simultaneous acquisition and processing of hyperspectral/multispectral fluorescence and reflectance images of objects using a single imaging device, combined illumination and filtering, software-controlled spectral selection, and integration with sorting machinery for automated agricultural commodity inspection.
Stated Advantages
Significantly reduces the cost and complexity compared to existing systems requiring multiple imagers or inspection stations.
Enables real-time automated inspection capable of quickly and accurately identifying defects and fecal contamination.
Provides flexibility to select wavelengths for reflectance and fluorescence imaging on-the-fly via software, eliminating the need for hardware changes.
Compatible with production line speeds for rapid sorting of agricultural commodities, processing over 50 items per second in tests.
Documented Applications
On-line quality and safety inspection of agricultural commodities, specifically simultaneous detection and sorting for fecal contamination and defects in fruits such as apples during commercial processing.
Integration with commercial-grade agricultural commodity sorting machines for simultaneous detection of defects and fecal contamination, using hyperspectral/multispectral reflectance and fluorescence line-scan imaging.
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