Opt Lett. 2018 May 15;43(10):2336-2339. doi: 10.1364/OL.43.002336.
We have developed a second harmonic photoacoustic microscopy (SH-PAM) for subdiffraction-limited imaging based on nonlinear thermal diffusion. When a sine-modulated Gaussian temperature field is introduced by a laser beam, the temperature dependence of the thermal diffusivity induces a nonlinear photoacoustic (PA) effect and thus results in the production of second harmonic PA signals. We demonstrate through both simulation and experiment that the second harmonic PA images can be reconstructed with a lateral resolution exceeding that of conventional optical resolution PA microscopy. The feasibility of SH-PAM was verified on phantom samples. Amphioxus zygotes and germinated pollens have been studied by SH-PAM to demonstrate its biomedical imaging capability. This method expands the scope of conventional PA imaging and opens up new possibilities for super-resolution imaging, prefiguring great potential for biological imaging and material inspection.
我们基于非线性热扩散开发了一种用于亚衍射极限成像的二次谐波光声显微镜 (SH-PAM)。当一束激光引入正弦调制的高斯温度场时，热扩散率的温度依赖性会引起非线性光声 (PA) 效应，从而产生二次谐波 PA 信号。我们通过模拟和实验证明，二次谐波 PA 图像可以用超过传统光学分辨率 PA 显微镜的横向分辨率来重建。SH-PAM 的可行性已在 phantom 样品上得到验证。通过 SH-PAM 研究了文昌鱼胚胎和萌发花粉，以证明其生物医学成像能力。这种方法扩展了传统 PA 成像的范围，为超分辨率成像开辟了新的可能性，预示着在生物成像和材料检测方面具有巨大的潜力。
