Fig. 3: Visualization and quantitative analysis of temperature fields.
a, b Full two-dimensional flow field images obtained simultaneously through a single shot, including the horizontal gradient image (a) and the vertical gradient image (b). The purple dashed box indicates the positions of the candle and heat gun. The displayed images present effective flow field information obtained by subtracting reference images captured in the absence of the flow field. c, d Light deflection induced by temperature variations in the flow field, with (c) corresponding to the thermal plume of the candle and (d) to the thermal airflow of the heat gun. D1 represents the distance from the candle wick to the measured thermal plume, and D2 represents the distance from the nozzle of the heat gun to the measured hot air. e, f Reconstructed results of the temperature distribution for the candle’s thermal plume (e) and the heat gun’s thermal airflow (f)
