Adaptive Active Illumination Via Translationally and Axially Tunable Cascaded Metasurfaces

Active three-dimensional sensing requires accurate light delivery and sufficient return-signal strength, while complex scenes require a tunable balance between local power concentration and illumination coverage. Collimated beam illumination supports a longer maximum detectable distance by concentrating optical power, whereas expanded beam illumination improves angular sampling efficiency by increasing coverage per projection. Existing active-illumination approaches typically use fixed illumination patterns or predefined scanning trajectories, making it difficult to balance local power concentration for maximum detectable distance with illumination coverage for sampling efficiency. Here we propose an adaptive active-illumination method based on translationally and axially tunable cascaded metasurfaces (TATCMs). TATCMs control the beam output angle within the field of view (FoV) through lateral translation and tune illumination coverage through axial-spacing tuning. At an operating wavelength of 905 nm, the implemented TATCMs demonstrate continuous beam-output-angle control across an approximately 70°×70° FoV under a ±300 µm lateral stroke, while increasing the interlayer spacing by 2.64 mm expands collimated beam illumination with a measured divergence of 0.06° to provide continuous coverage across the FoV. Adaptive three-dimensional reconstruction further demonstrates the potential of TATCMs as a compact planar illumination platform for scene-adaptive three-dimensional sensing in autonomous vehicles, unmanned aerial vehicles, and industrial robotics.