A Novel UAV-Based Ultra-Light Weight Spectrometer for Field Spectroscopy

A novel hyperspectral measurement system for unmanned aerial vehicles (UAVs) in the visible to near infrared (VIS/NIR) range (350-800 nm) was developed based on the Ocean Optics STS microspectrometer. The ultralight device relies on small open source electronics and weighs a ready-to-fly 216 g. The airborne spectrometer is wirelessly synchronized to a second spectrometer on the ground for simultaneous white reference collection. In this paper, the performance of the system is investigated and specific issues such as dark current correction or second order effects are addressed. Full width at half maximum was between 2.4 and 3.0 nm depending on the spectral band. The functional system was tested in flight at a 10-m altitude against a current field spectroscopy gold standard device Analytical Spectral Devices Field Spec 4 over an agricultural site. A highly significant correlation (r(2) > 0.99) was found in reflection comparing both measurement approaches. Furthermore, the aerial measurements have a six times smaller standard deviation than the hand held measurements. Thus, the present spectrometer opens a possibility for low-cost but high-precision field spectroscopy from UAVs.