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.

Using a hollow waveguide resonator, laser operation in the far infrared (FIR) has been observed on several transitions between 40 and 200 μm from methyl alcohol excited by the resonant absorption of CO2 pump laser lines. The preliminary performance characteristics of FIR waveguide lasers constructed from both metallic and dielectric tubes are discussed. For CO2 pump powers of a few watts, cw output power at the milliwatt level in the FIR was observed from waveguide laser structures only a small fraction of the size of conventional FIR laser resonators.

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