A Non-Invasive Remote Pressure Sensor Design for Extreme Environments Using Tunable Optics With Conventional Manometry

This paper presents the design of a non-invasive, non-contact remote pressure sensor using free-space optics, an electronically controlled variable focus lens (ECVFL), and a standard liquid manometer to monitor pressure inside high temperature and pressure chambers in harsh and hazardous environments. The proposed sensor does not require transparent manometers, and cameras in close proximity to determine pressure as the manometer liquid level are monitored remotely. This sensing mechanism is ideal for use in toxic environments, such as chemical plants as well as volatile and combustible units, such as oil refineries. Furthermore, the use of a low-power Gaussian laser beam for remote measurements mitigates the risk of destabilizing a semistable combustible system. Two experiments using manometers with identical and non-identical columns were performed as a proof-of-concept. Average measurement resolutions of 0.011 and 0.047 kPa corresponding to the relative resolutions of 0.109% and 0.085% are demonstrated in the two experiments. With the chosen ECVFL model, the sensor can deliver impressive 1700 measurements/min for stable pressure conditions and acceptable 60 measurements/min for drastically fluctuating pressure conditions in harsh environments.