The fluorescence box (FloX) is an unique instrument, enabling the continous observation of chlorophyll fluorescence. It measures spectral data of extremely high resolution, yet is built to withstand the hazards of a permanent outdoor installation.
It represents the evolution of prototypes such as the Multiplexer Radiometer Irradiometer (MRI), SFLUOR box and SIF-System developed from a collaboration between Jülich Research Center and the Remote Sensing of Environmental Dynamics Laboratory of the University Milano Bicocca. The basic routines of the FloX are based on SPECY (Forschungszentrum Jülich, IBG-2: Plant Sciences).
The FloX is specifically designed to passively measure chlorophyll fluorescence under natural light conditions. Therefore the design is optimized to achieve maximum efficiency in terms of: Signal to Noise Ratio, Spectral Resolution and quick acquisition time. The core of the system is the QEPro spectrometer from Ocean Optics covering the Red/Near Infrared region (650 – 800 nm). This is the spectral range where chlorophyll fluorescence is emitted and where the two atmospheric oxygen absorption bands (O2B and O2A, at 689 nm and 760 nm respectively) are used to measure it. Upward and downward channels of the FloX allow to measure the solar irradiance and the reflected radiance from the canopy. In order to keep a stable level of dark current the spectrometers are embedded in a temperature controlled housing. The signal-to-noise is maximized thanks to accurate automatic optimization of the signal of both channels and a high performance optical light throughput.