Discrete liquid level fiber sensor

Abstract

A novel simple fiber sensor to sense liquid level is presented. The operation principle is based on the relative Fresnel reflective intensity. The sensor consists of a fiber splitter with the configuration of one input to multiple fiber outputs, i.e. 1×4, 1×8 and 1×12 arrangements that act as a discrete liquid level. A broadband source (BBS) is used as the light source supply. The total reflected power intensity is measured using a power meter. Experimental results show that the power intensity decreases as the level of liquid is increased. The sensor has a simple configuration, low cost, and it can be customized for a wide height measurement range spanning from a few centimeters up to a hundred meters.

Multiplexed Passive Optical Fiber Sensor Networks for Water Level Monitoring: A Review

“…In the quasi-distributed OFS network, the multiplexing allows a single interrogation system (i.e., a single optical source and a single detector) to support multiple SUs, enhancing the system performance, as well as the practicability (in terms of install and operation costs/efforts) [14,30]. As summarized in Table 2, various multiplexing techniques have been proposed for the OFS network with discrete SUs [31][32][33][34][35][36][37][38][39][40][41][42][43]. The multiplexing techniques can be categorized into (a) wavelength division multiplexing (WDM), (b) time division multiplexing (TDM), (c) coherence division multiplexing (CDM), and (d) space division multiplexing (SDM), as shown in Figure 3.…”

“…As shown in Figure 5a, the SDM system has a similar architecture to that of TDM, except that the interrogation system in the monitoring station uses the OPM instead of the OTDR unit [41]. To be specific, an amplified spontaneous emission (ASE) light output of the C-band BLS is divided by the 1 × N optical coupler at the remote node, where each channel's output (of the optical coupler) is back-reflected at the end facet of the SU.…”

“…However, the sum of the reflected optical power decreases as the water level rises. Thus, there is a linear relation between the measured optical power and the level of water, which could be used to estimate the actual water level [41].…”

“…decreases as the water level rises. Thus, there is a linear relation between the measured optical power and the level of water, which could be used to estimate the actual water level [41]. The SDM system features the simple architecture that could be implemented with off-the-shelf optical components.…”

16 Ch × 200 GHz DWDM-Passive Optical Fiber Sensor Network Based on a Power Measurement Method for Water-Level Monitoring of the Spent Fuel Pool in a Nuclear Power Plant

“…However, such high resolution is achieved at the expense of the measurement range [16,17]. On the other hand, the discrete level sensors utilize multiple sensing units (SU) that are installed, e.g., inside the water pool to capture the environmental data, where the SUs can be implemented with optical filters (e.g., Fabry-Perot cavities [18][19][20] and Bragg grating [21][22][23]) or optical reflectors (e.g., optical fiber tips [6,7,24,25]). The use of multiple SUs requires optical (or electrical) multiplexing techniques [26][27][28], and thus would result in limited resolution.…”