Long-range thermal imaging using a millimeter-wave source

Summary form only given. This paper describes a remote sensing concept that involves active thermal imaging with a millimeter-wave source (ATIMS). High frequency (HF) microwave or millimeter wave radiation can be beamed onto a target, thus generating rapid transient temperature increases in different portions of the target area. The time-dependent thermal contrast can be measured using sensitive infrared (IR) imagers. The technique can in principle be used in many situations where passive infrared imaging is currently used. This talk will include a description of the concept, a discussion of potential advantages and issues, model calculations of the predicted time-dependent temperature profile for various source intensities and materials, and results from preliminary laboratory proof-of-principle experiments. The experiments were performed at the HF microwave materials processing facility at NRL, where an 83 GHz gyrotron has been used to rapidly heat a variety of simple and complex targets. Thermal imaging with a sensitive mid-wavelength IR camera reveals clear signatures in a variety of target configurations. Potential applications include long range detection of explosive devices. Although a variety of heating sources have been used for active thermal imaging, including lasers, flashlamps, and longer wavelength microwaves, millimeter waves appear to be particularly well-suited for long range applications