In poor visibility environmens such that a space is filled with smoke or dust, optical methods such as cameras are not sufficient to grasp the spatial situation, and alternative methods are needed. Especially in the decommissioning work of the Fukushima Daiichi Nuclear Power Plant, a method that enables spatial recognition not only in poor visibility but also under high radiation dose is required. This study conducted a basic investigation of the use of ultrasonic waves as a spatial visualization technique that is promissing for such harsh environments. Ultrasonic waves generating and receiving with 40 kHz air-coupled ultrasoic sensors were measured in the pitch-catch configuration, traveling distance being about from 200 mm to 800 mm, in a case filled with mosquito coil smoke, and it was confirmed that sufficient ultrasonic waveforms could be measured even in the poor visibility environment. In the future, we will construct a phased array system with multiple air-coupled ultrasonic sensors to visualize objects in such conditions.
HAYASHI et al. (Wed,) studied this question.