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Amplified OTDR systems for multipoint corrosion monitoring.

Nascimento JF, Silva MJ, Coêlho IJ, Cipriano E, Martins-Filho JF - Sensors (Basel) (2012)

Bottom Line: The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment.The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration.Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

View Article: PubMed Central - PubMed

Affiliation: Polytechnic School of Pernambuco, University of Pernambuco (UPE), Recife, PE, Brazil. jehanfonseca@hotmail.com

ABSTRACT
We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

No MeSH data available.


OTDR relative intensity (B-A’) for the corrosion of the Al film under gain changes: (a) from 20 dB to 17 dB and (b) from 17 dB to 20 dB.
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f7-sensors-12-03438: OTDR relative intensity (B-A’) for the corrosion of the Al film under gain changes: (a) from 20 dB to 17 dB and (b) from 17 dB to 20 dB.

Mentions: We also investigated the effect of EDFA gain variations that may occur between two consecutive measurements of the OTDR trace evolution. These variations may occur in real applications due to changes in the laser pump power (aging effect), or even due to changes in EDF temperature [11]. Figure 6(a) shows measurements of the OTDR relative intensity as a function of corrosion time with a change in EDFA gain, from 20 dB to 17 dB, in the indicated point. In Figure 6(b) the gain changes from 17 dB to 20 dB. As could be expected, the measured corrosion time was not altered by the changes in EDFA gain. However, we can observe, especially in Figure 6(b), that there was a peak in the curve due to the gain change. Note that Figure 6 is obtained as the ratio of point B and point A (B-A) shown in Figure 4(b). The point B is the reflection level from the sensor head and it is sensitive to gain changes, but point A, which is a reference level, is not, because it is zero. Therefore, this sensitivity to gain changes could be minimized or even removed if another reference level is used, a reference that is also affected by the gain change. For example, the point A’ shown in Figure 4(b) is also affected by the gain changes, similarly to the point B. If we recalculate the OTDR relative intensities of Figure 6 using the point A’ instead of point A, we obtain the curves shown in Figure 7(a,b), which show almost no sign of gain changes. Therefore, the proper choice of the reference level to obtain the relative intensities is important to guarantee the immunity of the obtained results to signal level changes, i.e., to keep it self referenced.


Amplified OTDR systems for multipoint corrosion monitoring.

Nascimento JF, Silva MJ, Coêlho IJ, Cipriano E, Martins-Filho JF - Sensors (Basel) (2012)

OTDR relative intensity (B-A’) for the corrosion of the Al film under gain changes: (a) from 20 dB to 17 dB and (b) from 17 dB to 20 dB.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376602&req=5

f7-sensors-12-03438: OTDR relative intensity (B-A’) for the corrosion of the Al film under gain changes: (a) from 20 dB to 17 dB and (b) from 17 dB to 20 dB.
Mentions: We also investigated the effect of EDFA gain variations that may occur between two consecutive measurements of the OTDR trace evolution. These variations may occur in real applications due to changes in the laser pump power (aging effect), or even due to changes in EDF temperature [11]. Figure 6(a) shows measurements of the OTDR relative intensity as a function of corrosion time with a change in EDFA gain, from 20 dB to 17 dB, in the indicated point. In Figure 6(b) the gain changes from 17 dB to 20 dB. As could be expected, the measured corrosion time was not altered by the changes in EDFA gain. However, we can observe, especially in Figure 6(b), that there was a peak in the curve due to the gain change. Note that Figure 6 is obtained as the ratio of point B and point A (B-A) shown in Figure 4(b). The point B is the reflection level from the sensor head and it is sensitive to gain changes, but point A, which is a reference level, is not, because it is zero. Therefore, this sensitivity to gain changes could be minimized or even removed if another reference level is used, a reference that is also affected by the gain change. For example, the point A’ shown in Figure 4(b) is also affected by the gain changes, similarly to the point B. If we recalculate the OTDR relative intensities of Figure 6 using the point A’ instead of point A, we obtain the curves shown in Figure 7(a,b), which show almost no sign of gain changes. Therefore, the proper choice of the reference level to obtain the relative intensities is important to guarantee the immunity of the obtained results to signal level changes, i.e., to keep it self referenced.

Bottom Line: The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment.The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration.Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

View Article: PubMed Central - PubMed

Affiliation: Polytechnic School of Pernambuco, University of Pernambuco (UPE), Recife, PE, Brazil. jehanfonseca@hotmail.com

ABSTRACT
We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

No MeSH data available.