Air Force Research Laboratory officials here recently completed an extensive bioeffects research program for an invisible, counter personnel, directed-energy weapon known as the Active Denial System.

Data showed that millimeter waves do not promote cancer or cause reproductive problems, and researchers also defined skin and eye exposure thresholds, as well as levels at which effective repel occurs.

Results demonstrate that the Denial System, or ADS, can be used operationally while maintaining a significant safety margin, thus making the device a landmark nonlethal weapon.

The bioeffects research effort also assisted hardware developers in their design of the novel weapon. The ADS program marks the first instance wherein a nonlethal weapon was founded on bioeffects research occurring prior to, rather than subsequent to, the weapons development process.

AFRL officials have been involved in researching the operationally useful effects of millimeter waves for almost 20 years.

These wavelengths occur in the one to 10 mm (0.04-0.4 in.) region of the electromagnetic spectrum, which means they are larger than infrared waves but smaller than radio waves or microwaves. Millimeter waves correspond to radio band frequencies of 30-300 GHz.

In the late 1980s, AFRL researchers discovered a particular effect of 94 GHz energy that ultimately became the basis for the ADS.

The system focuses a beam of millimeter waves occurring at this 94 GHz frequency.

The effect is a rapid heating of the human target's (adversary's) skin that is extremely uncomfortable and ultimately prompts the individual to flee the beam. The AFRL Joint Nonlethal Weapons Directorate, Air Force Force Protection Battlelab, and Office of the Secretary of Defense Advanced Systems and Concepts Office funded ADS development through an Advanced Concept Technology Demonstration.

This produced two versions of the system: a mobile version that has since served as a technology demonstrator and a containerized version that is suitable for operational deployment.