First in Europe and now in the U.S., recyclers are coming to depend on SWIR-based spectroscopy for sorting plastics in the waste stream, as the images below illustrate. Cost effective SWIR 1024 or 512 element linescan cameras with wavelength sensitivities ranging from 1100 to 2200 nm are mounted onto a spectrograph. While monitoring the sorting conveyor, the spectrograph rapidly identifies the polymer type inherent in the waste and triggers the diversion of the waste into its proper bin.

Mountains of plastics wait to be sorted and recycled. Plastic sorting systems such as the one above can use SUI linescan-based spectrometers, image courtesy of LLA Instruments.

Near infrared (NIR) spectroscopy identifies and sorts PE-HD, PE-LD, PP, PET, PET-G, PS, PVC, and similar plastics found in automotive, electronic, and household products. The plastics are first ground into little pellets and then sorted using a shortwave IR camera system. Of particular value is the ability of shortwave IR devices to sort black plastics; this detection and separation process is difficult to accomplish in the visible spectrum.