COMMUNICATIONS: Laser secures troop communications

A compact semiconductor-laser-based transmitter and receiver device provides secure portable communications for military applications. Lack of radio-frequency transmission makes the communicator less susceptible to enemy interception, according to the Air Force Phillips Laboratory (Kirtland AFB, Albuquerque, NM), which developed the system.

At the heart of the communicator is a near-infrared diode laser compatible with night-vision goggles. Several laser frequencies are being investigated by Phillips developers to optimize performance and maximize eye safety. The transmitter, which is about the size of a small flashlight, includes a zoom lens that increases the beam divergence and enables it to double as an infrared illuminator. Designed communication range is up to1 km but can be as far as 2 km with the narrowest beam. Using a 9-V rechargeable battery, the communicator operates for four hours. In enclosed spaces, the wide beam can be used to scatter laser light off walls and ceilings, allowing use as an intercom.