SPONSORED: REMOTE THERMAL HYPERSPECTRAL IMAGING Going


hyperspectral Gemma Church explains how the Telops Hyper- Cam is unlocking thermal infrared hyperspectral imaging for everyone


T


hermal infrared hyperspectral imaging is an advanced technique, where


images are collected with an additional dimension of data. It ‘represents a significant increase in analytical capability over traditional, point-based optical analysis techniques,’ according to Benjamin Saute, a field applications engineer at Telops. With traditional imaging, optical information is collected over two spatial dimensions to create a photographic representation of a scene. With hyperspectral imaging, a third data dimension is also collected, capturing the spectral content of the scene, which contains information about the chemical species present. Saute explained: ‘Our three- dimensional data product is called a hypercube, and can be thought of as a traditional two-dimensional thermal image with a continuous infrared radiance spectrum associated with each individual pixel. The infrared radiance spectra can be correlated with libraries of known signatures to allow for high-specificity chemical imaging.’ Hyperspectral imaging is a major step forward, compared to traditional, point-based chemical analysis techniques. This is because, while these point-based methods provide great fidelity of the spectral


18 Electro Optics April 2021 Hyper-Cam Airborne Mini


signal, they lack the spatial information contained in a hypercube. ‘To get this kind of spatial


resolution with a point sensor, you are going to need to make multiple measurements across your desired area,’ said Saute. ‘This is expensive, time-consuming, and only affords you with limited spatial resolution. Hyperspectral imaging is the best of both worlds, in that we can generate high-quality spatial and spectral information from a single measurement.’ Using thermal infrared


hyperspectral imaging, many individual images are collected over multiple discrete wavebands. The Hyper-Cam from Telops, for example, uses an interferometer coupled to a 2D focal plane array detector. The interferometer collects single waveband images across the entire spectral range of the detector. On-board electronics are then used to generate the hypercube data product and apply a radiometric calibration to yield a calibrated infrared spectral radiance datacube.


Sky-high spectral analysis Thermal hyperspectral imaging is emerging as a reliable technique for routine aerial surveys for the detection of fugitive emissions, such as volatile organic compounds (VOCs) from industrial locations. For example, the Telops


Hyper-Cam airborne platform is often mounted to an aircraft and flown over the area of interest. The Hyper-Cam continuously collects hypercubes as the aircraft flies, searching for infrared spectral radiance signatures that match the target compounds. This collected data is then used to create a gas detection map in post- processing.


Thermal infrared


hyperspectral imaging is also widely used in ground-based configurations. The Hyper-Cam can also be installed in a fixed location to provide quantitative VOC measurements from stack emissions, or to monitor for gas leaks at an industrial facility for health and safety purposes, for example. But challenges exist for


this novel imaging technique,


particularly when it comes to the access of both the instrumentation and data. Saute explained:


‘Hyperspectral imagers are often highly complex optical devices requiring significant investment in construction and operator training and, as a result, have not been widely proliferated among the scientific and research communities. ‘Now that there are commercial thermal infrared hyperspectral imaging systems such as the Telops Hyper-Cam, hardware proliferation has increased, making access to such measurement platforms less difficult.’


This is an important point.


The Telops Hyper-Cam is a commercial off-the-shelf product, meaning anyone with an interest in thermal infrared hyperspectral imaging can acquire a system without having to invest significant resources into the design and construction of a custom device.


‘The Hyper-Cam is operated using RevealPro software which allows the user full control over operational and measurement


@electrooptics | www.electrooptics.com


Telops / Photon Lines


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