Photoacoustic endoscopy shows promise in the detection of gastrointestinal cancer, inflammation, and other lesions. High-resolution endoscopic imaging of the hemodynamic response necessitates a small-sized, high-sensitivity ultrasound sensor. Here, we utilize a laser ultrasound sensor to develop a miniaturized, optical-resolution photoacoustic endoscope. The sensor can boost the acoustic response by a gain factor of ω_o/Ω (the frequency ratio of the signal light and measured ultrasound) by measuring the acoustically induced optical phase change. As a result, we achieve a noise-equivalent pressure density (NEPD) below 1.5 mPa·Hz^−1/2 over the measured range of 5 to 25 MHz. The heterodyne phase detection using dual-frequency laser beams of the sensor can offer resistance to thermal drift and vibrational perturbations. The endoscope is used to in vivo image a rat rectum and visualize the oxygen saturation changes during acute inflammation, which can hardly be observed with other imaging modalities.

光声内窥镜在检测胃肠道癌症、炎症和其他病变方面显示出前景。血液动力学响应的高分辨率内窥镜成像需要小型、高灵敏度的超声传感器。在这里，我们利用激光超声传感器开发了一种小型化、光学分辨率的光声内窥镜。通过测量声学引起的光学相变，传感器可以将声学响应提高增益因子ω _o /Ω（信号光和测量超声波的频率比）。因此，我们实现了低于 1.5 mPa·Hz ^{−1/2的噪声等效压力密度 (NEPD)}在 5 至 25 MHz 的测量范围内。使用传感器的双频激光束的外差相位检测可以提供对热漂移和振动扰动的抵抗力。内窥镜用于对大鼠直肠进行活体成像，并可视化急性炎症期间的氧饱和度变化，而其他成像方式很难观察到这一点。