HYPERSPECTRAL IMAGING Spectral snapping
Matthew Dale explores the emerging alternatives to push broom hyperspectral imaging
T
he majority of hyperspectral imaging cameras used in industry today are line scan devices based on push
broom sensors. Snapshot technologies provide an alternative, capturing an entire hyperspectral data cube in one sensor readout without needing to combine images. Now, an EU project has recently begun to
build SWIR hyperspectral chips, while an Italian firm has introduced a hyperspectral camera that uses Fourier transform technology. Snapshot hyperspectral sensors have
been around for a decade, with the advantage of easy integration into industrial equipment and fewer motion artefacts compared to line scan devices. A compromise often has to be made,
however, between spatial and spectral resolution when designing hyperspectral snapshot cameras, something that German company, Cubert, found when building its early cameras. Te firm’s first Firefleye Q285 model offered 50 x 50-pixel spatial resolution, and could capture 125 spectral channels between 450 and 950nm via a prism-based sensor. It expanded its portfolio with the Butterfleye x2 camera, which, using a filter-on-chip, could provide an image resolution of 512 x 272 pixels, but could only capture up to 25 spectral channels. Recently, Cubert has introduced a
Cubert’s Ultris 20 hyperspectral snapshot camera provides a more reliable alternative for aerial surveillance than conventional line scan cameras
hyperspectral camera equipped with fundamentally new snapshot technology that enables it to offer both high spatial and spectral resolution. Called Ultris 20, the camera offers 400 x 400-pixel native image resolution and captures 100 spectral channels between 450 and 850nm. According to Cubert, it is the first
hyperspectral camera based on light field technology, where both the intensity and
8 IMAGING AND MACHINE VISION EUROPE FEBRUARY/MARCH 2020
direction of incident light rays are used to capture data. Equipped with a 20-megapixel CMOS sensor, a continuously variable bandpass filter from Delta Optical Tin Film, and a lenslet array, the camera is able to capture multiple images of a scene in a single shot – each image taken with an optical bandpass filter featuring a different centre wavelength. Te camera can acquire images at the
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Cubert
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