A dual-field-of-view spectrometer system for reflectance and fluorescence measurements (Piccolo Doppio) and correction of etaloning

A lightweight, wirelessly controlled or autonomous, dual-field-of-view spectrometer system for environmental monitoring from rotary-wing unmanned aerial vehicles or for fixed deployment on masts at research sites has been developed. This system can incorporate up to two USB controlled and fibre-optic based spectrometers. This will enable the selection of spectrometers with different spectral resolutions and sampling intervals for a diverse range of applications. For example, spectrometers to measure both reflectance across the visible near infrared and the O2-A and O2-B spectral regions can be incorporated. This will advance the near-ground measurement of sun-induced fluorescence in support of space-based observations and for photosynthesis process model validation. A new high performance spectrometer from Ocean Optics, the QE Pro, can be used with this system. However, as the QE Pro has a back-thinned detector, it suffers from etaloning to some degree. To enable the use of the QE Pro to determine sun-induced fluorescence requires that this etaloning be corrected. The linearity of the QE Pro and nature of etaloning displayed have been investigated. Two methods to correct etaloning were then tested and the results presented here and recommendations made.