講演情報
[9p-E219-15]Toward a Portable LED-Based Spectrometer for Infrastructure Inspection (1)
- Feasibility Demonstration of Multi-Wavelength Switching Spectroscopy -
〇(P)Miezel Legurpa Talara1, Ryouta Arata2, Yudai Matsumura2, Masayuki Higaki2, Yu Tokizane1, Takao Ueda1,3, Takeshi Yasui1 (1.Inst. of Post-LED Photonics (pLED), Tokushima Univ., 2.Graduate Sch. of Sci. and Tech. for Innovation, Tokushima Univ., 3.Graduate Sch. of Techn., Industrial and Social Sci., Tokushima Univ.)
キーワード：
Near-Infrared Spectroscopy、LED-Based Spectrometer、Nondestructive Evaluation
Aging concrete infrastructure has increased the demand for nondestructive inspection technologies capable of supporting preventive maintenance. Near-infrared (NIR) spectroscopy is a promising approach for evaluating deterioration indicators such as chloride concentration and moisture content; however, conventional NIR spectrometers are often expensive and bulky due to their reliance on broadband light sources, spectrometers, and array detectors. In this study, we investigate a multi-wavelength switched NIR method as a first step toward the realization of a compact LED-based spectrometer for infrastructure inspection. Five wavelengths associated with chloride and moisture evaluation were selected, and a proof-of-concept system was implemented using a broadband halogen light source combined with wavelength-selective band-pass filters to emulate sequential LED operation. Mortar specimens with chloride concentrations of 0, 5, 10, and 20 kg/m³ were measured using only the selected wavelength components. The differential absorbance index related to chloride concentration exhibited a monotonic increase with increasing chloride content, demonstrating successful quantitative evaluation without full-spectrum acquisition. Moisture measurements also showed clear changes in the absorbance index during drying, indicating the capability to monitor moisture behavior non-destructively. These results demonstrate that deterioration indicators can be extracted using a limited number of discrete wavelengths and support the development of a compact, low-cost, time-multiplexed NIR spectrometer employing wavelength-selected LEDs and a single InGaAs photodiode for on-site infrastructure diagnosis.