Passive real-time hyperspectral imager based on Fabry-Pérot interferometer filter technology

This paper presents the system design of a real-time hyperspectral imager based on tunable Fabry-Pérot interferometer (FPI) filter technology. This passive hyperspectral instrument is able to capture spectral data at a rate corresponding to video-like image feed. The instrument is designed to be suitable for handheld operation as well as for missions carried out using uncrewed aerial vehicles. The frame rate of individual spectral channels of an FPI-based camera, and subsequently the acquisition speed of hyperspectral data, depends on the actuation speed of the FPI filter, exposure time of the sensor, data transfer rate, and all delays between the consecutive operations. In order to minimize the delays when switching between the spectral channels, the large FPI of this instrument is enclosed in a low-pressure housing to reduce air resistance, which would otherwise slow down the mechanical movement of the filter. As various applications require different sets of wavelengths and a variable number of spectral channels to be recorded, the imager enables selecting the desired wavelengths programmatically from within the complete spectral range of the instrument. FPI-based hyperspectral cameras produce a full two-dimensional image for each spectral channel. The spatial information contained in the images may be used to compensate for any desired or undesired movement of the imager. The spatial information available for individual channels can also be used for data analysis, and it enables employing conventional machine vision algorithms for example to detect and track the objects of interest.