Coupled optical-thermal energy spreading composites for wearable laser protective equipment

In collaboration with the University of Virginia and Raytheon, TauMat is proposing to continue our development of thin, lightweight, soldier-portable, laser-protective equipment to provide protection and enhance solider lethality on the modern battlefield. The protective equipment will utilize a combination of multiply scattering high temperature ceramic fiber to disperse the laser light, a high conductivity graphite thermal spreader, and an insulating layer. This structure will be designed to effectively broaden the incident laser spot while diffusely reflecting a portion of the beam, absorb and rapidly distribute heat laterally to limit temperature rise at the point under irradiation, and protect the points of contact with the soldier from dangerous temperatures. The key innovation of the proposed composite device is the utilization of a multiply scattering ceramic fiber mat, which serves multiple key functions: it spreads the laser light before absorption by the graphite to mitigate temperature spikes at the incident site, absorbs some of the light energy over a large volume in a high surface area structure that promotes convective and radiative cooling at the site of absorption, and diffusely reflects a portion of the beam, rapidly reducing the power density of any escaping light to levels safe for surrounding personnel. Experimental testing of our Phase I demo composites showed that versions of our composite can withstand >471 W while meeting the program temperature goal. However, the structure tested is too heavy to meet the Phase II area-density requirements. Modeling of our optimized, lightweight version indicates our proposed structure exceeds the requirements to withstand 100 W/cm2 incident radiation at powers up to 275 W for 60 s without exposing the soldier to temperatures ? 44 °C. Working closely with the Army and partners, two form-factors of soldier-portable PPE utilizing the composites developed in Phase I will be designed, built, and tested under laser irradiation in Phase II. These prototypes will include integrated sensors for strike detection and consideration will be given to soldier-portability and combat readiness.