光声成像综合了光学成像和超声成像的优点，在具备声学穿透深度的同时，保留了光学丰富对比度。在声学分辨率光声成像（AR-PAM）中，为了获得高成像质量，通常采用大数值孔径的聚焦性超声探头。然而由于探头的焦深有限，在离焦区域，光声图像的横向分辨率和信噪比会显著降低。基于虚拟点的合成孔径技术，有助于解决AR-PAM在失焦区域横向分辨率下降的问题。目前，AR-PAM合成孔径聚焦技术已经发展了多种算法，包括一维合成孔径聚焦、二维合成孔径聚焦、自适应合成孔径聚焦、基于空间脉冲响应的合成孔径聚焦，以及基于延迟相乘和的合成孔径聚焦等。本文对这些算法的优缺点进行评价总结，并展望了其在未来发展中的前景。

Photoacoustic imaging is a hybrid imaging method that integrates optical contrast and ultrasound penetration, reserving the advantages of both the optical imaging and the ultrasonic imaging. In acoustic-resolution photoacoustic imaging (AR-PAM), focused transducers with large numerical are usually applied to AR-PAM to achieve high image quality. However, the lateral resolution and signal-to-noise ratio of photoacoustic images degrade significantly in the out-of-focus region due to the limited focal depth of transducer. To address this challenge, algorithms of synthetic aperture focusing technology (SAFT) based on virtual point concept have been developed. These include one-dimensional-SAFT, two-dimensional-SAFT, adaptive-SAFT, spatial impulse response-based scheme, and delay-multiplication-sum solution. This review introduces the advantages and limitations of these algorithms, and discusses their outlooks for future developments in AR-PAM.