Fig. 1. Isotropic and anisotropic absorption principles. (a) Absorption coefficient of isotropic absorber in traditional photoacoustic imaging; (b) vector distribution of absorption coefficient of actual anisotropic absorber; (c) variations of photoacoustic signals produced by two linearly polarized beams with 90°(0°, 90°) difference between electric vectors with angle θ; (d) specific parameter ζ=tan2θ of molecular ordering varies with angle θ

Fig. 2. Experimental device[18]. (a) Diagram of experimental device; (b) characterization of system resolution

Fig. 3. Verification of polarized photoacoustic imaging method. (a) Photoacoustic imaging results excited in different electric vector directions; (b) statistical values of photoacoustic signals of sample in figure 3(a) vary with angle θ; (c) diagram of molecular chain orientation structure of PVA material; (d) photoacoustic imaging result induced by linearly polarized light with 0°; (e) photoacoustic imaging result induced by linearly polarized light with 90°; (f) statistical values of photoacoustic si

Fig. 4. Biological sample imaging. (a) Sample photo; (b) imaging region; (c) conventional photoacoustic imaging result; (d) photoacoustic imaging result stimulated by linearly polarized light with 0°; (e) photoacoustic imaging result stimulated by linearly polarized light with 90°; (f) imaging result of parameter ζ