Abstract
The thermal visualization based on two-color in near infrared range has been achieved by developing a thermal imager system built up of multi-peak optical filter and color CCD camera. The present technique enables two-color thermal imager to measure lower temperature (>500°C) with higher spatial resolution, compared with traditional two-color thermal imagers. The performance of the prototype thermal imager is evaluated in the present paper. The upper limit of repeatability at around 1000°C has been shown to be ∼3°C and ∼0.2°C (1σ level) with the spatial resolution of ∼10μm and ∼300μm, respectively. In addition, measurement of high temperature machining of stainless steel with ceramic tool tip is performed to examine the advantage of the present technique. The maximum temperature of tool tip is shown to be ∼680°C by the prototype thermal imager, while it is ∼300°C by the infrared thermography based on the wavelength of 5μm. The observed inconsistency is interpreted to be because of not only the emissivity independency but also the higher spatial resolution by the present technique.
