Quantum Dot Based Optical Taggants for Combat Identification

ABSTRACT: Physical Sciences Inc. (PSI), working with Northrop Grumman Electronic Systems (NGES), proposes to develop a passive optical Identification-Friend-or-Foe (IFF) patch that utilizes the absorptive and emissive properties of quantum dots (QDs) to provide a unique signature when interrogated by a weapons targeting pod. The patch will be a flexible, robust, and low-cost composite capable of being placed on military vehicles, soldiers, and buildings. During the Phase I program PSI evaluated, through a quantitative system model, the feasibility of detecting a passive QD-based IFF indicator at operationally relevant standoff distances using the operating characteristics of a laser targeting pod. In parallel, chemical procedures were developed that produced QDs that emit light within the wavelength range of a targeting pod"s sensors. These procedures, as well as an overcoating method that was developed to improve the emission quantum yields and stability of the QDs, provide a foundation for preparing these materials. In the Phase II program, PSI will build upon the system model and synthetic procedures while incorporating the QDs into a polymer composite in order to deliver a prototype with a TRL value of 5 to the Air Force. The patch will be evaluated under realistic solar and thermal conditions. BENEFIT: The proposed research will provide the military with a rugged, low cost, passive indicator of friendly or non-combatant individuals or entities prior to a targeted weapons deployment. The successful completion of the development program will enable the Air Force to limit or eliminate friendly fire casualties and unnecessary destruction of military equipment or non-combatant property during air-to-ground attacks. In addition, the proposed IFF patch can be extended to applications beyond its current requirements because its spectral output can be deliberately controlled. For example, the use of tunable QD emission, coupled with spectrally selective sensors and eye-safe excitation, could lead to spectral barcodes used to track high value targets tagged at a checkpoint and through an urban environment.