Short-wave infrared (SWIR) spectral imager based on Fabry-Perot interferometer for remote sensing

Rami Mannila; Christer Holmlund; Harri J. Ojanen; Antti Näsilä; Heikki Saari

doi:10.1117/12.2067206

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7 October 2014 Short-wave infrared (SWIR) spectral imager based on Fabry-Perot interferometer for remote sensing

Rami Mannila, Christer Holmlund, Harri J. Ojanen, Antti Näsilä, Heikki Saari

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Proceedings Volume 9241, Sensors, Systems, and Next-Generation Satellites XVIII; 92411M (2014) https://doi.org/10.1117/12.2067206
Event: SPIE Remote Sensing, 2014, Amsterdam, Netherlands

Abstract

VTT Technical Research Centre of Finland has developed a spectral imager for short-wave infrared (SWIR) wavelength range. The spectral imager is based on a tunable Fabry-Perot interferometer (FPI) accompanied by a commercial InGaAs Camera. The FPI consists of two dielectric coated mirrors separated by a tunable air gap. Tuning of the air gap tunes also transmitted wavelength and therefore FPI acts as a tunable band bass filter. The FPI is piezo-actuated and it uses three piezo-actuators in a closed capacitive feedback loop for air gap tuning. The FPI has multiple order transmission bands, which limit free spectral range. Therefore spectral imager contains two FPI in a stack, to make possible to cover spectral range of 1000 – 1700 nm. However, in the first tests imager was used with one FPI and spectral range was limited to 1100-1600 nm. The spectral resolution of the imager is approximately 15 nm (FWHM). Field of view (FOV) across the flight direction is 30 deg. Imaging resolution of the spectral imager is 256 x 320 pixels. The focal length of the optics is 12 mm and F-number is 3.2. This imager was tested in summer 2014 in an unmanned aerial vehicle (UAV) and therefore a size and a mass of the imager were critical. Total mass of the imager is approximately 1200 grams. In test campaign the spectral imager will be used for forest and agricultural imaging. In future, because results of the UAV test flights are promising, this technology can be applied to satellite applications also.

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Rami Mannila, Christer Holmlund, Harri J. Ojanen, Antti Näsilä, and Heikki Saari "Short-wave infrared (SWIR) spectral imager based on Fabry-Perot interferometer for remote sensing", Proc. SPIE 9241, Sensors, Systems, and Next-Generation Satellites XVIII, 92411M (7 October 2014); https://doi.org/10.1117/12.2067206

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