The spin Hall effect of light (SHEL), the transverse splitting of light into two circularly polarized components via refraction or reflection, offers high-precision, nondestructive inspection of unknown interfaces when combined with a signal amplification technique called weak measurement. However, its application in detecting dynamics is limited due to its multistep process. Here, we condense the procedure into a single step, enabling calibration-free, single-shot measurement of the SHEL by replacing one component of the conventional setup with a polarization beamsplitting metasurface. Our approach allows for instantaneous evaluation of the SHEL, even with fluctuations in the original beam position. As proof of concept, we apply metasurface-assisted weak measurements to both static and dynamic scenarios, where the experimental results obtained from a single captured image demonstrate nice agreement with theory. This real-time observation of the SHEL highlights its potential for high-precision monitoring of dynamic processes such as biomedical sensing and chemical analysis.

Spin-orbit coupling, a fundamental mechanism underlying topological insulators, has been introduced to construct the latter's photonic analogs, or photonic topological insulators (PTIs). However, the intrinsic lack of electronic spin in photonic systems leads to various imperfections in emulating the behaviors of topological insulators. For example, in the recently demonstrated three-dimensional (3D) PTI, the topological surface states emerge, not on the surface of a single crystal as in a 3D topological insulator, but along an internal domain wall between two PTIs. Here, by fully abolishing spin-orbit coupling, we design and demonstrate a 3D PTI whose topological surface states are self-guided on its surface, without extra confinement by another PTI or any other cladding. The topological phase follows the original Fu's model for the topological crystalline insulator without spin-orbit coupling. Unlike conventional linear Dirac cones, a unique quadratic dispersion of topological surface states is directly observed with microwave measurement. Our work opens routes to the topological manipulation of photons at the outer surface of photonic bandgap materials.