Tuesday, February 16, 2010

Laser Beam Eavesdropping - 2010

It is time to update our views on laser beam eavesdropping. While not entirely practical yet as an everyday amateur/business spy tool, advancements are being made which have us concerned.

Last year, researchers from Bar-Ilan University (Ramat-Gan, Israel) and the Universitat de València (Burjassot, Spain) developed a new way to sense sound remotely using a laser beam. Their paper is called: "Simultaneous remote extraction of multiple speech sources and heart beats from secondary speckles pattern" by Zeev Zalevsky, Yevgeny Beiderman, Israel Margalit, Shimshon Gingold, Mina Teicher, Vicente Mico, and Javier Garcia.

Unlike classic laser beam eavesdropping, the new method does not rely on interferometer or a reflecting diaphram, like a window. A single laser beam is aimed at the object to be monitored (a person and a cell phone were used in their tests). The speckles that appear in an out-of-focus image of the object are then tracked. This produces data from which a spectrogram or sound signal can be constructed.
The setup is basic. The laser illuminates a small area on the object and an ordinary digital camera captures the scene. The camera's lens is defocused. This produces a pattern that does not randomly change when the object moves. The camera image is processed, calculating the shift of the pattern from frame to frame. (more

Laser beam audio samples...
Heartbeat at 60m.
Note: Audio is labeled as they were in the paper. However, it sounds like the neck and face audio clips may have been reversed.