Real-time imaging of methane gas from a UAV mounted system

Methane gas is widespread in both industry and in domestic settings, but leaks into the environment pose a great risk both in terms of individual safety and climate. We previously presented a low cost methane imaging system that utilises backscattered illumination techniques to directly image methane gas in real time. This device was capable of imaging leaks with flow rates on the order of 0.05 L/min at a 3m range. The system illuminates a scene using tunable laser diodes centred at the methane absorption near 1653nm, with the backscattered light collected and imaged by a standard short-wave infrared focal plane array. Information obtained with the infrared images can be used in combination with a live visible feed to highlight exactly in the scene the source of the methane. We present a modified system for use on a UAV. Firstly the system, which utilises differential imaging, had to be altered in order to increase the image stabilisation to compensate for the increased amount of movement. Secondly, the impact of sunlight on the system was explored with imaging conducted both during the day and at night. We demonstrate the use of this system mounted to a UAV, imaging at an altitude of 3m and variety of horizontal range. It is demonstrated that performance is variable depending on surface-type, and sunlight level. It is envisaged that such a device would improve the ease of use for both routine facility or city pipeline inspections.