Calibration of a fluorescence hyperspectral imaging system for agricultural inspection and detection

Abstract

Fluorescence hyperspectral imaging is increasingly being used for food quality inspection and detection of potential food safety concerns. The flexible nature of a self-scanning pushbroom hyperspectral imager lends itself to these kinds of applications, among others. To increase the use of this technique there has been a tendency to use low cost off-the-shelf hyperspectral sensors which are typically not radiometrically calibrated. To ensure that these systems are optimized for response and repeatability, it is imperative that the systems be both radiometrically and spectrally calibrated specifically for fluorescence imaging. Fluorescence imaging provides several challenges such as low signal, stray light and a low signal dynamic range that are improved with careful radiometric calibration. A radiometric and spectral approach that includes flat fielding and the conversion of digital number responses to radiance for calibrating this imaging system and other types of hyperspectral imagers is described in this paper. Results show that this method can be adopted for calibrating fluorescence and reflective hyperspectral imaging systems in the visible and near infra-red domains.