Optical Fiber Light Pattern Measurement Without Path Length Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low coherence optical interference methods require precise optical path length adjustment and stable installation environments, limiting the measurement of light intensity distribution patterns to relatively short optical fibers, making it difficult to measure km-order long optical fibers used in actual transmission paths.
Innovation Solution
A method involving multiplexing continuous light after transmission through an optical fiber with local high coherence light for coherent detection and performing digital autocorrelation processing on the signal to measure light intensity distribution patterns without adjusting the propagation delay time of the reference light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical path length of reference light is adjusted to match propagation delay time of each propagation mode, then accurate light intensity distribution pattern measurement is achieved, but the measurement is limited to relatively short optical fibers and requires precise optical system design and stable installation environment
Solution Approach 1:
The patent replaces the mechanical adjustment of optical path length with digital signal processing. Instead of physically adjusting the reference light path to match propagation delay times, the system uses digital correlation processing on the detected signals to achieve mode identification and light intensity distribution pattern measurement without mechanical optical path adjustment.
Solution Approach 2:
The patent changes the approach from adjusting optical path length parameters to processing signal time parameters digitally. By changing from physical parameter adjustment (optical path length) to digital parameter processing (signal correlation in time domain), the system eliminates the need for precise mechanical adjustment while maintaining measurement accuracy.
2Device complexity
If the movable range of optical path length of reference light is limited, then the optical system design becomes simpler, but the measurable optical fiber length is limited to relatively short fibers
Solution Approach 1:
The patent replaces mechanical optical path length adjustment with digital signal processing, allowing the system to measure light intensity distribution patterns in optical fibers of any length without requiring the optical path length to be physically adjustable over large ranges. The digital correlation processing handles the time delay differences regardless of fiber length.
3Measurement precision
If precise optical path length adjustment is required, then measurement accuracy is improved, but the installation environment stability requirement increases
Solution Approach 1:
The patent eliminates the need for stable installation environment by replacing mechanical optical path adjustment with digital signal processing. The digital correlation processing is insensitive to environmental changes that would affect mechanical optical components, thereby maintaining measurement accuracy without requiring stringent environmental stability.
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
Enables measurement of light intensity distribution patterns in long optical fibers without requiring optical path length adjustment, simplifying the measurement process and reducing the need for precise optical system design and environmental stability.
Implementation Method 1
continuous light from a low coherence light source is branched
Implementation Method 2
the light is multiplexed with transmitted light from the optical fiber under measurement, and the multiplexed light is received by a two-dimensional imaging sensor
Implementation Method 3
multiplexing continuous light after transmission through an optical fiber under measurement and local light having high coherence to perform coherent detection
Implementation Method 4
performing digital autocorrelation processing on a signal obtained by the coherent detection
Data Source
AI summary
A light intensity distribution pattern measurement device according to the present disclosure includes: a two-dimensional imaging sensor for receiving multiplexed light that is obtained by multiplexing transmitted light obtained by injecting one branched light of first continuous light into an optical fiber under measurement, reference light that is the other branched light of the first continuous light, and local light; and a signal processing unit for performing digital signal processing on a light reception signal I (t) of each pixel obtained by the two-dimensional imaging sensor, in which the signal processing unit measures a light intensity distribution pattern, by calculating a square of an autocorrelation function between the light reception signal I (t) and a light reception signal I (t+τ) obtained by shifting the light reception signal by time τ, for each pixel of the two-dimensional imaging sensor.