Maintaining and modulating mechanical anisotropy is essential for biological processes. However, how this is achieved at the microscopic scale in living soft matter is not always clear. Although Brillouin light scattering (BLS) spectroscopy can probe the mechanical properties of materials, spatiotemporal mapping of mechanical anisotropies in living matter with BLS microscopy has been complicated by the need for sequential measurements with tilted excitation and detection angles. Here we introduce Brillouin light scattering anisotropy microscopy (BLAM) for mapping high-frequency viscoelastic anisotropy inside living cells. BLAM employs a radial virtually imaged phased array that enables the collection of angle-resolved dispersion in a single shot, thus enabling us to probe phonon modes in living matter along different directions simultaneously. We demonstrate a precision of 10 MHz in the determination of the Brillouin frequency shift, at a spatial resolution of 2 µm. Following proof-of-principle experiments on muscle myofibres, we apply BLAM to the study of two fundamental biological processes. In plant cell walls, we observe a switch from anisotropic to isotropic wall properties that may lead to asymmetric growth. In mammalian cell nuclei, we uncover a spatiotemporally oscillating elastic anisotropy correlated to chromatin condensation. Our results highlight the role that high-frequency mechanics can play in the regulation of diverse fundamental processes in biological systems. We expect BLAM to find diverse applications in biomedical imaging and material characterization.

维持和调节机械各向异性对于生物过程至关重要。然而，如何在活的软物质的微观尺度上实现这一点并不总是清楚的。尽管布里渊光散射 (BLS) 光谱可以探测材料的机械性能，但由于需要使用倾斜的激发和检测角度进行连续测量，因此使用 BLS 显微镜对生物体中的机械各向异性进行时空绘图变得复杂。在这里，我们介绍布里渊光散射各向异性显微镜（BLAM），用于绘制活细胞内的高频粘弹性各向异性。BLAM 采用径向虚拟成像相控阵，能够在单次拍摄中收集角度分辨色散，从而使我们能够沿不同方向同时探测生物体中的声子模式。我们展示了在 2 µm 空间分辨率下确定布里渊频移的精度为 10 MHz。在对肌肉肌纤维进行原理验证实验后，我们将 BLAM 应用到两个基本生物过程的研究中。在植物细胞壁中，我们观察到壁特性从各向异性转变为各向同性，这可能导致不对称生长。在哺乳动物细胞核中，我们发现了与染色质凝聚相关的时空振荡弹性各向异性。我们的结果强调了高频力学在调节生物系统中多种基本过程中可以发挥的作用。我们期望 BLAM 在生物医学成像和材料表征领域找到多种应用。