Multi-wavelength photoacoustic (PA) imaging has been studied extensively to explore the spectroscopic absorption contrast of biological tissues. To generate strong PA signals, a high-power wavelength tunable pulsed laser source has to be employed, which is bulky and quite expensive. In this Letter, we propose a hybrid multi-wavelength PA imaging (hPAI) method based on the combination of a single-wavelength pulsed laser source and multi-wavelength continuous-wave (CW) laser sources. By carefully controlling the laser illumination sequence (pulse-CW-pulse) and extracting the PA signal difference before and after the heating of CW lasers, the optical absorption property of multi-wavelength light illumination could be obtained. Compared with conventional PA imaging, the proposed hPAI shows a much lower system cost due to the usage of single-wavelength pulsed lasers and multiple inexpensive CW lasers. As the preliminary results show in this Letter, hPAI imaging has the potential to provide another pathway for high spectroscopic optical absorption contrast in PA imaging.

中文翻译：

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混合多波长非线性光声传感和成像

多波长光声（PA）成像已被广泛研究以探索生物组织的光谱吸收对比。为了产生强的PA信号，必须使用高功率的波长可调脉冲激光源，它体积大且价格昂贵。在这封信中，我们基于单波长脉冲激光源和多波长连续波（CW）激光源的组合，提出了一种混合多波长PA成像（hPAI）方法。通过仔细控制激光照射顺序（脉冲-CW-脉冲）并提取CW激光加热前后的PA信号差，可以获得多波长光照明的光吸收特性。与传统的PA成像相比，由于使用了单波长脉冲激光器和多个廉价的连续波激光器，因此所提出的hPAI显示出低得多的系统成本。正如这封信中的初步结果所示，hPAI成像有潜力为PA成像中的高光谱光学吸收对比度提供另一条途径。