Fig. 2: Reflective multi-view stereoscopic capsule photo-thermoelectric (PTE) imager.

a Schematic of the module and its fundamental operation mechanism. Operation of the reflective multi-view stereoscopic capsule PTE imager of the Methods section describes the corresponding detailed conditions. b Non-destructive reflective multi-view stereoscopic capsule photo-imaging inspection of a glass beverage bottle (in the sub-terahertz (sub-THz: λ = 1.15 mm) frequency region) in which metallic impurities were concealed by an opaque coating. The impurities were visualised via detecting local reflection signals corresponding to their locations. c Remote hierarchical image extraction of a multi-layered columnar object via the reflective multi-view stereoscopic capsule multi-frequency band sensing. The figure represents the measurement setup in sub-THz (λ = 1.15 mm) and near-infrared (NIR: λ = 870 nm) frequency regions. The module driving in these two bands performed image extractions of d, the outer shell (NIR), and the inner core (sub-THz). We employed 30-µm-thick SWCNT films as the light-absorbing impurities. e Simple image restoration of the multi-layered columnar object by covering the inner hierarchical image with the outer hierarchical one. Here, the multi-view stereoscopic PTE images were scanned at a speed of 10 Hz (b, d).