Radar-based inspection system scans food for foreign objects
No one likes the idea of biting into a cookie (or other food item) and finding a piece of glass, wood or plastic inside. An experimental new system is designed to keep that from happening, utilizing radar technology.
Currently, many food production facilities X-ray their finished products to check that metal objects (such as loose screws from production-line machinery) haven't made their way inside. Unfortunately, though, those X-rays often miss items composed of plastic, wood or glass.
That's where the SAMMI system is intended to come in.
Created by engineers at Germany's Fraunhofer Institute for High Frequency Physics and Radar Techniques, it utilizes extremely high frequency radio waves. These are emitted by a rotating "transmitting antenna" located above a conveyor belt, on which food products are carried past. A "receiving antenna," situated below the conveyor belt, detects those waves after they've travelled through the food items and the belt.
By precisely analyzing how much time passes between each wave being transmitted by the one antenna and received by the other, the system is thus able to determine the degree to which each food item slows the waves down. If the item contains only the ingredients that it's supposed to, that delay falls within a predetermined range. If the delay is longer, however, it means that there's an unwanted "extra ingredient" in there.
SAMMI alerts workers to the situation, displaying the location of the foreign object within a radar image of the food product. Among other things, the setup has so far been successfully used to detect glass splinters within the chocolate filling of sandwich cookies.
The current prototype measures 40 x 40 x 30 cm (15.7 x 15.7 x 11.8 in) and can be used to inspect items up to a maximum size of 30 x 30 x 5 (11.8 x 11.8 x 1.9 in). That said, it could conceivably be built to any size, and would even work on prepackaged foods. The technology does not detect metal, though, so it would have to be used in conjunction with X-ray inspection systems.
Hübner Photonics is already marketing a spinoff of the system, aimed at the inspection of letters and small packages.