FLEX: An imaging spectrometer for measurement of vegetation fluorescence

FLEX: An imaging spectrometer for measurement of vegetation fluorescence

Smorenburg, K.
Visser, H.
Court, A.J.
Stoll, M.P.
Technisch Physische Dienst TNO - TH

Otrio, G. (editor)

2017

Detection of vegetation fluorescence gives information about plant functioning, stress and vitality. During the past decades several ground based laser fluorosensors have been developed to investigate these processes and to demonstrate the value of this technique. FLEX (= FLuorescense EXplorer) is a space mission to measure the fluorescence of vegetation on earth over large areas from space. Such a mission would greatly improve the understanding and enhance the capability to quantify e.g. the role of terrestrial vegetation in global carbon sequestration. Because the fluorescence signal, which is excited by solar irradiation is low with respect to the reflected sunlight the signal from a satellite is proposed to be measured in the solar Fraunhofer lines, where the reflection signal is much reduced. The heart of FLEX is a high resolution imaging spectrometer with 2 channels: channel 1 around the Fraunhofer lines at delta = 397 nm, delta= 423 nm and/or delta = 434 nm and channel 2 around the Fraunhofer line at delta = 656 nm. The required spectral resolution will depend on the linewidth (0.02-0.3 nm). A first definition of the field of view is 8.4 degrees, leading from an 800 km satellite altitude to a swath of about 120 km. For detection a 1024 x 1024 pixel frame transfer CCD detector is proposed, with a pixel dimension of 13 x 13 um2.The maximum footprint is about 500 x 500 m2. The optical configuration contains a scan mirror for solar calibration, for pointing the FOV in swath direction and for freezing the observed ground scene up to a few seconds to increase the signal to noise performance. At this moment the concept of FLEX is elaborated in a feasibility study. Both the scientific and instrument requirements are updated and the concept is studied in detail. Besides a development plan for FLEX is made. In this paper the idea and the headlines of FLEX are described.

Fluorescence
Fraunhofer line detection
Imaging spectrometer

http://resolver.tudelft.nl/uuid:fe189ef9-d30f-4b24-80b9-9c061c0a623b

https://doi.org/10.1117/12.2307906

784925

SPIE

978151061627

0277-786X

International Conference on Space Optics, ICSO 2000, 5-7 December 2000, Toulouse Labège, France, 10569

Proceedings of SPIE - The International Society for Optical Engineering

conference paper