CALIBRATION OF A PUSHBROOM HYPERSPECTRAL IMAGING SYSTEM FOR AGRICULTURAL INSPECTION

Abstract

A method to calibrate a pushbroom hyperspectral imaging system has been demonstrated for use in agriculturalinspection where the imaged object is close to the imaging system. The method consists of a modified geometric control pointcorrection to remove smile and keystone effect from the system, and both wavelength and distance calibrations to reduce thewavelength and distance errors to less than 0.5 nm and 0.01 mm (across entrance slitwidth), respectively. Next, apixelbypixel percent reflectance calibration was performed at all wavelengths with dark current and 99% reflectancecalibrationpanel measurements, and results were verified with measurements on a certified gradient Spectralon panel withnominal values ranging from 12% to 99%. Results indicate that the method is capable of calibrating the hyperspectral systemacross the entire spectral range of the detector, but errors increase below 420 nm and above 840 nm. Further research shouldbe performed to evaluate the stability of the calibration over time, and techniques must be developed to implement thecalibration for realtime analysis.