Broadband Non-Destructive structural reconstruction via reflection angle estimation using carbon nanotube thin-film sensors

Computer vision (CV) in the long-wavelength optical band is attracting attention as a method for non-destructively extracting detailed information (material identification and structural reconstruction) from the inside of objects that are opaque to the naked eye. The wavelength range utilizes millimeter-wave, terahertz, and infrared bands to identify non-metallic materials such as plastics, glass, semiconductors, and ceramics, which are the core of industrial products. In terms of structural reconstruction, CV, which is mainly used to estimate external shapes in visible light, is extended to millimeter-wave, terahertz, and infrared bands, and is expected to be applied to the field of inspection technology. Specifically, there are silhouette measurement method using differential viewpoints called VH and detailed shape measurement method extending VH called CT. Here, the carbon nanotube (CNT) film sensor ultra-broadly performs photo-detection operations over the existing sensors in comparable sensitivities with the conventional narrowband devices at each region. All of these methods satisfy both shape restoration and material identification by performing multi-wavelength measurement.

As above stated, conventional broadband, multi-wavelength long-wavelength optical CV measurement is mainly based on transmission systems. However, there are still restrictions on the materials of the objects to be observed. Specifically, it is difficult to distinguish between absorption and reflection of irradiated objects in transmitted long-wavelength light CV measurements.

For this situation, this study established a prototype system for non-destructive material identification and structural repair using reflectometry in the infrared band as an initial study. The reflective long-wavelength optical sensing measurement system mainly consists of a CNT thin-film scanner sheet. The aforementioned optical characteristics allow the CNT film scanner sheet to facilitate highly flexible combinations of measurement wavelengths according to the observed material for measurements in the millimeter-wave and infrared bands, where inspection performance is excellent. These properties make CNT thin film sheets suitable for non-destructive inspection of internal conditions.This work facilitates the use of nanomaterials, such as CNT, in inspection fields.

Mr. Mitsuki Kosaka is a graduate student at Chuo University. After graduating from the same university, he continued his studies there through internal admission. He is a member of the Kawano Laboratory at Chuo University, where he is researching the development and validation of non-destructive inspection technologies using devices with CNT-based detection sensors.