What if airline passengers could leave their shoes on while still being scanned for security? Pacific Northwest National Laboratory (PNNL) partnered with the U.S. Department of Homeland Security (DHS) Science & Technology Directorate (S&T) to build the millimeter-wave shoe scanner developed the Millimeter-Wave Shoe Scanner — a solution that relies on proven state-of-the-art imaging to improve throughput at aviation security checkpoints. Leveraging decades of experience with millimeter-wave technology, PNNL and DHS S&T's system can quickly scan footwear from under a person’s feet. Similar to the full-body scanners at the airports, which also use harmless millimeter waves, the scanner looks for concealed threats in the soles of shoes. When a passenger steps on the scanner, millimeter waves pass through the shoe’s material, reflecting any concealed items, and subsequently produces a high-resolution, three-dimensional (3-D) image using low-power holographic radar imaging technology, in a matter of seconds. Millimeter-wave technology has been proven to use non-harmful, ultra-high-frequency radio waves to detect and identify concealed objects in airport security body scanners nationwide. This innovative technology can integrate with existing architectures, streamlining security screening while sustaining detection capabilities that protect our nation’s travelers.