OPTICAL FIBER STRAIN SENSOR SYSTEM AND METHOD

摘要

An optical fiber strain sensor system and method are provided that use pixels of a three-dimension (3-D) pixel sensor to sense the respective light beams passing out of the ends of a reference fiber and a measurement fiber and for converting the respective light beams into respective electrical signals. Because 3-D camera pixels have photodiodes that are directly connected by switches to integrators within the same die, the need to use separate TIAs and phase detection circuitry in each receive channel is eliminated, which reduces system complexity and overall cost. In addition, omitting the separate TIAs and phase detection circuitry for each channel eliminates the phase uncertainty that can occur when using those components, and thus improves measurement precision.

主权项

1. An optical fiber strain sensor system comprising:
a signal generator that generates a modulated electrical signal; at least a first light source that receives the modulated electrical signal and produces a modulated optical signal having a first phase; at least a measurement optical fiber secured to a structure; an optical coupler that receives the modulated optical signal and couples at least a measurement optical signal portion of the modulated optical signal into at least a first end of the measurement optical fiber; a three-dimensional (3-D) pixel sensor having at least a first pixel, the measurement optical signal portion passing out of a second end of the measurement optical fiber and being received by the first pixel and being converted by the first pixel into a first electrical sense signal, the first pixel having a first pixel circuit, the first pixel circuit receiving a clock signal used by the signal generator to generate the modulated electrical signal and cross-correlating the clock signal with the first electrical sense signal to produce a first cross-correlation result; an analog-to-digital converter (ADC) that receives the first cross-correlation result and converts the first cross-correlation result into a first digital cross-correlation result; and phase difference determination logic that receives at least the first digital cross-correlation result from the ADC, the phase difference determination logic processing at least the first digital cross-correlation result to determine a change in the phase of the measurement optical signal and to determine, based on the change in the phase of the measurement optical signal, a change in a length of the measurement optical fiber, and wherein the change in the length of the measurement optical fiber is indicative of stress or strain in the structure to which the measurement optical fiber is secured.