3D Pixel Sensor Optical Fiber Strain Measurement
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Solution Overview
Problem
Current optical fiber strain sensor systems are complex and expensive, with separate transimpedance amplifiers (TIAs) and phase detection circuitry for each receiver channel, leading to reduced measurement precision due to phase uncertainty.
Innovation Solution
The system employs a 3-D pixel sensor with integrated photodiodes and switching transistors to cross-correlate optical signals, eliminating the need for separate TIAs and phase detection circuitry, and uses a signal generator to produce modulated signals for precise phase difference determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate transimpedance amplifiers and phase detection circuitry are used for each receiver channel, then the system can perform phase measurements, but the system complexity and cost increase
Solution Approach 1:
The patent merges the transimpedance amplifier and phase detection circuitry into a single integrated pixel circuit within the 3-D pixel sensor. Each pixel contains both the TIA and phase detection functionality, eliminating the need for separate external circuitry and reducing overall system complexity while maintaining measurement precision
Solution Approach 2:
The pixel circuit is designed to perform multiple functions: it acts as both a photodetector and a phase measurement device. The same pixel circuit that converts optical signals to electrical signals also performs the phase detection through cross-correlation with the clock signal, making the system more efficient and less complex
2Measurement precision
If separate transimpedance amplifiers are used for each receiver channel, then the system can convert optical signals to electrical signals, but phase uncertainty increases due to TIA limitations
Solution Approach 1:
By integrating the phase detection circuitry directly into the pixel circuit, the patent eliminates the phase uncertainty introduced by separate TIAs. The cross-correlation process within the integrated circuit uses the original clock signal directly, avoiding the phase distortion that occurs when signals pass through external amplifier stages
Solution Approach 2:
The system uses cross-correlation of the received optical signal with the original clock signal to determine phase information. This feedback mechanism allows the system to accurately track phase changes without being affected by the phase uncertainty introduced by external amplifiers, as the correlation process references the known clock signal
3Measurement precision
If multiple separate circuit components are used for phase detection, then the system can measure phase differences, but the cost increases
Solution Approach 1:
The patent combines multiple separate circuit components (photodetector, transimpedance amplifier, phase detection circuitry) into a single integrated pixel circuit that can be manufactured using standard semiconductor fabrication processes. This integration significantly reduces the number of discrete components needed, lowering manufacturing cost while maintaining phase difference measurement capability
Solution Approach 2:
The patent uses a digital copying approach where the analog optical signal is converted to a digital representation through cross-correlation processing. The phase information is extracted from the digital cross-correlation results, eliminating the need for expensive analog phase detection circuitry and reducing overall system cost
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the system, reduces costs, and enhances measurement precision by directly converting optical signals into electrical signals within the same die, improving the accuracy of strain measurements.
Implementation Method 1
The 3-D pixel sensor has at least a first pixel that receives the measurement optical signal portion passing out of a second end of the measurement optical fiber and converts it into a first electrical sense signal
Implementation Method 2
The signal generator generates a modulated electrical signal that is received by a first light source, which produces a modulated optical signal having a first phase
Data Source
AI summary
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.