From Figure , it can be seen that 3D confocal microscopy struggled to fully resolve the structure, likely due to the size and density issue aforementioned. To overcome this challenge, we utilized high-resolution SEM imaging to investigate the permanent optical matter formed by subdiffraction limit particles. High-resolution SEM imaging of the optical matter formed by 300 nm PS nanoparticles revealed a close-packed structure with distinct discrete patterns (Figure ). We observed random tightly packed arrangement, with small structural units distributed across the assembly. However, For the 200 nm polystyrene particles, a random 3D packing structure was observed, characterized by a highly dense and close-packed order. This arrangement suggests that, despite the randomness in particle placement, the structure achieves a relatively high degree of packing efficiency (Figure ). Since the image was captured using SEM, only the surface pattern of the structure can be observed. However, based on the z-depth information obtained from 3D confocal imaging, we estimate that the packing consists of approximately 8 layers of nanoparticles for the 300 nm particles and 12 layers for the 200 nm particles, respectively.