生物组织对光的散射使得光束通过透镜后无法在组织的深层(大于1 mm 处)聚焦，制约了需要光能聚焦的成像技术(如共聚焦显微、双光子显微)在生物医学领域的应用。为了抑制生物组织的散射效应，将光聚焦到深层组织，需要对入射光的波前进行调制。基于此要求，以下三种光学聚焦技术得以提出并发展：用待聚焦区的光强作为反馈信号的波前整形技术；将声光调制和时间反演(或光学相位共轭)技术相结合进而在散射介质内部实现光学聚焦的技术；对散射介质传输矩阵进行测量的光学聚焦技术。本文对上述光学聚焦技术的研究进展进行了综述，比较并展望了其在生物医学领域中的应用前景。

The light passing through lens cannot be directly focused inside biomedical tissues at depth deeper than 1 mm due to strong scattering, which fundamentally limits the use of imaging techniques such as confocal microscopy and two-photon microscopy, since these techniques demand confined light focusing inside tissues. To suppress the effect of light scattering in tissues and focus light deeper, the optical wavefront illuminating tissues should be modulated. To this end, three kinds of techniques are proposed: the wavefront shaping technique which uses the optical intensity in the wanted light-focused zone as the feedback; the time-reversed technique which combines acousto- optic modulation with optical phase conjugation aiming to focus light inside tissues; the technique of measuring transmission matrix of scattering media. These three techniques are reviewed and compared, while a technical prospect is given as for their biomedical applications.