TECH FOCUS: HYPERSPECTRAL IMAGING g
based on colour or shape – I’m going to put all the containers in the HDPE bin. But in reality [packaging] switches back and forth between PET and HDPE.’ Camirand showed an example of two lids that are identical to look at, but made of different plastics. ‘We really need hyperspectral,’ he said. ‘Tey all look white, crushed containers, which humans or [RGB] AI cannot differentiate between. We really need to rely on additional signal, which is hyperspectral, to classify them.’ One of Waste Robotics’ projects in
Prévost, QC, Canada, is sorting 30 parts per minute of polystyrene. ‘Right now it’s not using hyperspectral, but the client has ordered a second line for differentiating the subtleties and different types of styrofoams. Hyperspectral is really key to deliver quality sorting,’ Camirand said. Waste Robotics is also working on other
Latest products
Among the recent products launched that are suitable for spectral imaging are lenses from Kowa, with a transmission of 450 to 2,000nm. Te lenses also have a reduced focus shift over this wavelength range – without visible-to-shortwave- infrared optics, users might need to adjust the focus by changing the illumination and changing the lens. Te one-inch format lenses
are available with focal lengths of 12mm, 25mm and 50mm, with 8mm, 16mm and 50mm following in October. Ximea has released a new
generation of hyperspectral cameras in the XiSpec series. Te new cameras, using sensors from Imec, include line scan and snapshot mosaic versions. Te XiSpec2 cameras
measure 26.4 x 26.4 x 32mm and weigh 32g. Te band-pass filters have been optimised to improve spectral performance. Te cameras are ideal for applications like precision agriculture, material science and medical imaging. For projects where integration into limited space is required, models with USB3 flat-ribbon connection or PCIe interface are available. Lighting provider Ushio has
updated its Spectro LED series with an indium gallium nitride (InGaN) chip that achieves an output power of 180mW at 500 to 1,000nm. Te 1mm2
chip
emits a total broadband visible to near-infrared spectrum, meaning multiple LEDs are not necessary to cover this hyperspectral wavelength band. Te SMBB package means there is no need for a heat-dissipation jig to accompany it. ProPhotonix has added a
hyperspectral LED line light to its Cobra MultiSpec platform. It has a spectral range from 400 to 1,000nm and excellent spatial and spectral uniformity. Te spectrum is well-matched to the Specim FX10 camera, for example, or machine vision cameras using the Sony IMX174 sensor. For applications covering an extended spectrum, the Cobra MultiSpec can be developed in configurations of up to 12 wavelengths, from 365 to 1,700nm. LEDs offer advantages
over traditional halogen light sources, including compactness, longer lifetimes and greater control of the emission spectrum. System designers will benefit from reduced-form factors, without the need for additional heat
30 IMAGING AND MACHINE VISION EUROPE AUGUST/SEPTEMBER 2021
‘Hyperspectral imaging gives Waste Robotics the ability to differentiate between different types of plastic... or wood’
functionality in its robot solutions, such as destacking items lying on top of each other on the conveyor. ‘We believe in multi-robots and the ability to scan once and dispatch pictures to robots,’ Camirand said. To do that the firm uses 3D sensors to give as precise a location of each piece in the stack as possible. Te aim is that none of the material is displaced as the robots handle the stack, so when the items get to the third robot they are still at the same location as when the original scan was made. ‘Tere’s a lot of people who think having a fast robot
is a solution, but having one fast robot is not as good as having two slower robots because you can distribute the workload,’ he added. AI is useful for distinguishing between
plastic bags on a conveyor, for instance, which is a complex computer vision challenge. Te AI algorithm will learn to see features like the knot in a refuse sack, or the valleys in between two bags. Every image from every sensor Waste
Robotics uploads to the cloud; it is building a huge database of images, including hyperspectral, 3D and RGB. Tat allows the company to train its neural networks centrally. If the client participates in collective robot learning – if they share their data – then whatever one robot is trained on, other robots within the network will benefit. ‘If a new container comes on the market and appears in Singapore, and the robot is taught there and starts picking it,
Optical fibre bundle from Sedi-ATI
extraction equipment, and excellent spectral control, allowing improved system optimisation and enabling new applications. Finally, French fibre optic provider, Sedi-ATI, suggests using custom fibre- optic bundles to perform hyperspectral imaging. Fibre optic bundles are a
flexible option for spectral or hyperspectral imaging, the firm said. Broadband optical fibres are particularly well suited to this type of application. Te image is reconstituted by using masks ordering each
optical fibre – the same imaging principle used in telescopes. A spectrometer would generally be used to get a reading from the fibre optic bundles. Te number of optical
fibres and their respective core diameters constitute the pixels of the transported image. Bundles of several hundred fibres can be assembled, with offsets of several tens of metres. One example Sedi-ATI gave
is a bundle of 200µm core diameter broadband optical fibres to form an image of about 800 pixels over a spectrum from 300nm to 2.1µm.
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