RESUMO
To correct the error caused by uneven distribution of target surface irradiance in the measurement of emissivity by the irradiation reflection method, a progressive method for calculating the surface irradiance for infrared extended sources was proposed, and its CPU-GPU heterogeneous operation speedup was realized based on the compute unified device architecture (CUDA). The proposed method calculated the radiation transfer at the scale of small surface sources while considering the multiple reflections between the sources, which better reflected the actual physical condition. The CUDA-based parallel speedup enabled calculation within a few seconds even for several data levels, which facilitated pixel-by-pixel analysis of surface emissivity measurements. In addition, the effectiveness of the proposed calculation method was analyzed by adjusting multiple scene parameters. The advantage of the proposed method was analyzed by comparing it with several irradiance calculation methods in terms of the result and correction effect on emissivity measurements. The speedup effect of CPU-GPU heterogeneous operation was analyzed by adjusting the calculation parameters. The results revealed that the proposed method could effectively calculate the irradiance distribution on the target surface regardless of the distance between the radiation sources, and the calculation consumed a very short time. It could correct the emissivity measurement errors caused by uneven irradiance and was of great significance to further improving the accuracy of emissivity measurements by the irradiation reflection method.
RESUMO
To achieve rapid and precise non-contact measurements of coating emissivity at room temperature, a measurement method based on infrared thermal imager was proposed. By applying two irradiations with different energies to the target and reference surfaces, the influences of atmospheric transmittance, radiation of the target itself, environmental radiation, and atmospheric path radiation were eliminated, thereby enabling accurate emissivity measurement. Experiments were designed for validation with a mid-wave infrared thermal imager and a surface blackbody as the radiation source. Several combinations of irradiation energy were set to investigate the effects of average energy and energy difference between the two irradiations on the measured results. The normal emissivity of the coated sample plate in the mid-wave band was measured to generate the image of coating surface emissivity. Then, the emissivity measurement results of the proposed method were compared with those of the energy method and the point emissivity measuring instrument under the same conditions, and the comparison indicated that the proposed method can effectively measure the emissivity of coating. Some factors causing measurement errors were analyzed. Finally, an experiment was designed to compare the measurement speed between the proposed method and the currently used methods, and the experimental results were analyzed.