Thermal imaging through ordered bundles of infrared-transmitting silver-halide fibers

Ordered bundles of infrared-transmitting silver-halide (AgClxBr1−x) fibers were fabricated by extrusion. Bundles of total area 5–20 mm2 and lengths 5–50 cm included 100–2500 individual fibers and the packing fraction was 0.2–0.3. Each of the individual fibers was transparent in the spectral range 3–30 μm, and therefore, the whole bundle was suitable for thermal imaging. The modulation transfer function was studied using the “bar chart” and the “knife-edge” methods. The resolution was found to be 4–5 lines/mm for a 900 fiber bundle. Thermal images of objects at room temperature were transmitted from the entrance ends to the exit ends of the bundles.