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 5μm to carry out infrared emission measurements on a miniature IR emitter of dimensions 30μm×30μm in the spectral range 8.5–13.5μm. 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.

A passive method of measuring the spectral emissivity and the temperature of materials in the mid- and the far IR is described both in theory and experiment. Theoretical evaluation and real measurements (spectral emissivity and temperature) of selective bodies utilizing IR transmitting silver halide optical fibers are presented. We carried out the theoretical evaluation and measurements for a multiband fiber-optic radiometer, which consists of a silver halide (AgClBr) infrared transmitting fiber, a dual-band cooled infrared detector, and a set of 18 narrow-band infrared filters, covering the 2–14μm spectral range. We performed the measurement on the two selective bodies which had a strong and a weak dependence of emissivity as a function of the wavelength. The body spectral emissivity, the body temperature, and the room temperature were measured simultaneously. The results of the theoretical evaluation agreed with the experimental results. We also discuss the assumptions and the limitations of performing such a measurement for bodies near room temperatures. This method for measuring spectral emissivity has applications in science, industry (semiconductor industry), and medicine.

An all-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature was constructed. Different spectral regions in the radiometer were obtained by use of hollow glass waveguides (HGWs) as filters. Using HGWs instead of bulk filters was advantageous because each HGW can be used as two different spectral filters when a dual-band IR detector is used. In addition, HGWs are much cheaper than the bulk IR filters that are usually used in such applications. For one graybody with a mean emissivity of 0.71, the estimated mean errors obtained for sample temperature, ambient temperature, and sample emissivity for all measured temperatures were 0.50% (approximately 1.65 K), 0.48% (approximately 1.4 K), and 7.3% (approximately 0.052) respectively. For a second graybody with a mean emissivity of 0.8 the estimated mean errors were 0.35% (approximately 1.2 K), 0.48% (approximately 1.4 K), and 5.0% (approximately 0.04), respectively.

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A fiber-optic radiometer is developed for accurate noncontact temperature measurements. Of compact and novel design, it is based on replacing the usual chopper with a simple shutter. The radiometer operates in a spectral range of 5-20 microm and uses a silver-halide IR-transmitting optical fiber. The radiometer has a temperature resolution of 0.1 degrees C, a time response of 200 ms, and a spatial resolution of approximately 1 mm. Theory, simulation, radiometer design and construction, and examples of experimental measurements are shown. The novel radiometer can be used in diverse applications in science, medicine, and industry.