Fig. 1. Principle of photothermal deflection spectroscopy
(a): Schematic diagram;(b): Principle of phtothermal deflection spectroscopy

Fig. 2. Experimental setup for kerosene flame measurement
PD: Photodiode; PSD: Position sensitive detector

Fig. 3. Probe signals when probe light is overlapped with pump (H₀) or over pump (H₁) light

Fig. 4. Velocity distributions of flame at heights of (a) 5 mm, (b) 8 mm, and (c) 11 mm

Fig. 5. Velocity distributions of flame at vertical planes of (a) -2 mm, (b) 0 mm, and (c) 2 mm from center

Fig. 6. Velocity distributions of flame at height of 4 mm when pump energy is (a) 20 mJ, (b) 40 mJ, and (c) 60 mJ