Active imaging experiments are described in the 300 microm-l mm-region of the far infrared (FIR) spectrum. Transmission data are presented for a wide variety of common materials indicating the range of applicability of FIR imaging to law enforcement or nondestructive testing. The FIR images of several objects are presented, and the practicality of FIR imaging is discussed in light of straightforward improvements that can be made in the simple imaging system employed in these studies.

Order-of-magnitude increases in output power and efficiency have been obtained from optically pumped FIR lasers using a new FIR waveguide laser geometry and a new output coupler. Conversion efficiencies 5–15% of the theoretical maximum are reported for several lines between 71 and 1222 μm and cw output of 400 mW at 118 μm and 40 mW at 496 μm are obtained from a laser 2 m in length. These results indicate that the stronger FIR transitions are capable of cw operation at the 0.1–1.0-W level for 100 W of CO2 pump power.

No abstract

A new safeguards system under development employs radiometers in the 100-300 GHz spectral band to detect contraband, including shielding materials (used to attenuate the gamma ray emissions from nuclear materials), weapons, or explosives covertly concealed on personnel. Clothing is highly transparent at these frequencies an^ imaging techniques can detect contraband by its emissivity and reflectivity differences relative to human tissues. Experimental data are presented and sample images are uss.i as a basis to discuss system advantages and limitations.

An all-weather, kilometer -range, high resolution battelfield imaging system, capable of detecting and identifying enemy targets, is of considerable importance.In that view, this paper seeks to describe a state -of-the -art scanning mirror imaging system operating in the 1.3mm atmospheric window that provides simulated data on resolution and expected target signatures. Both passive and active imaging is performed using scale model targets to simulate reasonable tactical scenerios.