A combined long period fiber grating multi‐parameter sensor

Purpose – The on‐line concentration and temperature measurement of solutions is of great interest as a means of quality production control in many industrial processes, such as in food service industry, pharmaceuticals industry, chemical industry and environmental engineering, especially for harmful solutions or solutions that cannot be reached by the operator. This paper seeks to address these issues.Design/methodology/approach – A high resolution all‐fiber multi‐parameter sensor system has been studied theoretically and experimentally. The sensor system can be used for on‐line monitoring of concentration and temperature simultaneously and dynamically. A combined long period fiber grating (CLPG) is used as the sensor head based on its resonance wavelength shifts being almost linearly with concentration and temperature, and also based on that the two applied resonance peaks have different concentration‐wavelength coefficients and different temperature‐wavelength coefficients. Two wavelength‐matched fiber ...