Compact hyperspectral imaging as potential in security, medicine and quality control

Engineers in Germany developed the system as a tool for optical sorting of products and precision agriculture. Hyperspectral imaging involves capturing more wavelengths of light that are visible to the human eye; the researchers, from the Friedrich Schiller University Jena and the Fraunhofer Institute for Applied Optics and Precision Engineering, also in Jena, call the technique 5D imaging because as well as capturing the spatial coordinates of the objects to which it is applied, it also captures the precise wavelengths of light reflected from the object from the visible to the near-infrared electromagnetic spectrum and how both variables change in time.

In a paper in the journal Optics Express, team leader Stefan Heist, of the Schiller University, who collaborated with Gunther Notni’s research group from Ilmenau University of Technology, explains how the project culminated in the building of a prototype imager, around the size of a laptop computer. This contains a pair of hyperspectral "snapshot cameras" which are arranged to capture 3D images in the same way that human eyes do. By identifying specific features of the objects that are present in both camera views, the device creates data points capturing the entire surface of the object in x, y and z coordinates. This, however, only works if the object has significant texture or structure. If this is not the case, the device uses a high-speed mechanical projector to illuminate the surface with moving aperiodic light patterns. This allows accurate mapping of the surface features, and hyperspectral reflectance information is then mapped onto the surface.