Accession Number:

AD1099297

Title:

Quantitative Amplitude Measuring Phi-OTDR Using Multiple Uncorrelated Rayleigh Backscattering Realizations

Descriptive Note:

Journal Article - Open Access

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States

Personal Author(s):

• Redding,Brandon
• Murray ,Matthew J.
• Davis ,Allen
• Kirkendall ,Clay

Report Date:

2019-11-14

Pagination or Media Count:

9.0

Abstract:

We propose and demonstrate a technique to perform quantitative strain sensing using the amplitude of the Rayleigh backscattered light in a modified phi-OTDR system. While standard amplitude measuring phi-OTDR sensors can identify the presence of strain, they cannot perform quantitative measurements because the amplitude of the Rayleigh backscattered light exhibits a non-linear and unpredictable strain response. Here, we demonstrate a technique to computationally recover a linear strain response from a set of uncorrelated Rayleigh backscattering measurements. Using a combination of frequency and polarization multiplexing, we constructed a phi-OTDR system capable of recording 18 uncorrelated Rayleigh backscattering measurements in parallel. By combining information from these 18 measurements, the sensor achieves a linear strain response with total harmonic distortion below -35 dB. The sensor is immune to signal fading, has a minimum detectable strain of 5 p epsilonroot Hz and a bandwidth of 500 kHz.

Descriptors:

• measurement
• detection
• acousto optic modulators
• scattering
• optics
• algorithms
• RESOLUTION
• SENSOR
• TEMPERATURE
• repetition rate

Subject Categories:

• Active and Passive Radar Detection and Equipment
• Fiber Optics and Integrated Optics
• Test Facilities, Equipment and Methods

Distribution Statement:

APPROVED FOR PUBLIC RELEASE