Scanning near field infrared radiometry for thermal imaging of infrared emitters with subwavelength resolution

We have developed a scanning near field microscopy system based on tapered silver halide fibers which had tips of diameters smaller than a wavelength. The system was calibrated for temperature measurement and then determined the dependence of the minimum resolvable temperature difference and that of the spatial resolution on the tip diameter. This system was used for measurement of the temperature distribution of miniature infrared (IR) emitters. As an example we used a tapered fiber of tip diameter 5 μm to carry out infrared emission measurements on a miniature IR emitter of dimensions 30 μm×30 μm in the spectral range 8.5-13.5 μm. These measurements made it possible to obtain the thermal image of the element with a subwavelength resolution. Such a system would be useful for measuring the temperature distribution on a scene simulator projector or on an integrated circuit.