Brillouin Frequency Analysis Device Digital Signal Processing

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Solution Overview

Problem

Existing Brillouin frequency domain analysis devices rely on analog vector network analyzers, leading to long measurement times, poor noise behavior, and limited dynamics, with the equipment being oversized, heavy, and expensive for field use.

Innovation Solution

A device for Brillouin frequency domain analysis utilizing digital signal processing, eliminating the need for analog filters and phase comparators, and incorporating a circulator for improved dynamics, with digital signal processing enabled by a PC or DSP, and direct digital synthesis for the reference signal generation, reducing the system's cost and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an analog vector network analyzer is used for Brillouin frequency domain analysis, then the measurement can be performed, but the measurement time is long and the dynamics are limited

Engineering Contradiction:
Improvemeasurement dynamicsVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the analog vector network analyzer with a digital signal processing system. The analog signal processing chain (analog filters, phase and amplitude comparators) is substituted by digital signal processing, which eliminates the settling time of analog filters and enables faster measurements while improving dynamics.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating mode from analog to digital signal processing. By using digital signal processing, the system achieves faster response times and improved measurement dynamics without sacrificing measurement accuracy, directly addressing the contradiction between measurement time and measurement dynamics.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If an analog vector network analyzer is used for Brillouin frequency domain analysis, then the measurement can be performed, but the system is oversized, heavy and expensive

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent replaces the bulky analog vector network analyzer with a compact digital signal processing system implemented on a PC or DSP platform. This substitution dramatically reduces the system weight and size while maintaining or improving measurement capabilities, making the system suitable for field use.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses software-based signal processing algorithms to replicate the functionality of the analog vector network analyzer. By implementing the measurement and analysis functions in software rather than hardware, the system achieves the same measurement capability with significantly reduced weight and cost.

Inventive Principle:
Principle #26Copying

3Reliability

If an analog vector network analyzer is used for Brillouin frequency domain analysis, then the measurement can be performed, but the noise behavior is poor and dynamics are limited

Engineering Contradiction:
Improvenoise behaviorVSAvoidsignal evaluation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the analog signal evaluation system with a digital signal processing system. This substitution improves noise behavior because digital processing can apply sophisticated filtering and signal averaging techniques without the constraints of analog component noise. The apparent increase in complexity is offset by the use of standard digital signal processing algorithms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 significantly improves measurement dynamics, reduces measurement time, and eliminates the need for a vector network analyzer, resulting in a more cost-effective and portable system capable of high-resolution strain and temperature profiling.

Implementation Method 1

The pump laser 120 and the Stokes laser 130 are set up for coupling laser light having a pump frequency and a Stokes frequency, respectively, into the sensor fiber 110. The frequency difference between the pump frequency and the Stokes frequency is in the range of acoustic phonons in the sensor fiber.

Methodology Applied
Scientific EffectStimulated Brillouin scattering: Brillouin Scattering

Implementation Method 2

A circulator for decoupling an optical measurement signal from the sensor fiber can be provided. The circulator 115 is adapted to decouple an optical measurement signal from the sensor fiber 110.

Methodology Applied
Scientific EffectOptical circulation: Waveguide (optics)

Implementation Method 3

Connected to the circulator 115 is an optical sensor 140, such as a photodiode. The optical signal coupled out via the circulator 115 can be converted into an analog measurement signal uSt by means of the sensor 140.

Methodology Applied
Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 4

The laser light provided by pump laser 120 is modulated by an electro-optical modulator (EOM) 125. Typically, this is a periodic modulation of the laser light.

Methodology Applied
Scientific EffectElectro-optic modulation: Electro-Optic Effects

Data Source

PatentEP2110646B1Device and method for Brillouin frequency range analysis
Publication Date: 2018.06.13 BAM BUNDESANSTALT FÜR MATERIALFORSCHUNG UND PRÜFUNG
  • EP2110646B1 patent drawingFigure 1
  • EP2110646B1 patent drawingFigure 2
  • EP2110646B1 patent drawingFigure 3~4

AI summary

The device (100) has an analyzing unit (170) for detecting a complex transfer function of a sensor fiber (110). The analyzing unit has a digital measurement signal input (171) and a digital reference signal input (173). The analyzing unit detects the function from a digital measurement signal and a digital reference signal input via the respective inputs. An analog to digital converter (160) is connected with the input (171) and converts an analog measurement signal (uSt) into the digital measurement signal. An independent claim is also included for a method for digital Brillouin frequency domain analysis.