DMD Measurement Using Lens Array Parallel Detection
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Solution Overview
Problem
Conventional methods for measuring differential mode delay (DMD) in optical fibers are laborious, time-consuming, and limited to laboratory settings, making field testing impractical and costly, especially when upgrading optical networks to support higher bandwidths.
Innovation Solution
The use of a Shack-Hartmann wavefront sensor system that enables parallel measurement of the entire optical fiber core across a two-dimensional plane, allowing for faster and more comprehensive characterization of optical fibers, including field testing, by emitting light into one end and receiving it at the other through a lens array and image sensor for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sequential measurement methods are used to measure DMD, then measurement precision can be achieved, but measurement time increases significantly and field testing becomes impractical
Solution Approach 1:
The patent transitions from sequential one-dimensional measurement (scanning across the fiber core) to parallel two-dimensional measurement by using a lens array to simultaneously capture the entire fiber core output. This dimensional change enables concurrent measurement of multiple spatial positions, dramatically reducing measurement time while maintaining precision.
Solution Approach 2:
The patent divides the measurement system into multiple parallel measurement channels through the lens array, where each lens element independently measures a portion of the fiber core. This segmentation allows simultaneous measurement of multiple spatial positions, converting a sequential process into a parallel one that reduces overall measurement time.
2Measurement precision
If conventional DMD measurement equipment is used, then accurate DMD data can be obtained, but the equipment is large, heavy, and requires complex alignment procedures
Solution Approach 1:
The patent replaces complex mechanical alignment systems with an optical field-based measurement approach. Instead of mechanically scanning and aligning components, the system uses a lens array to optically capture the entire fiber core output, eliminating the need for complex mechanical positioning and alignment procedures while maintaining measurement accuracy.
Solution Approach 2:
The lens array serves multiple functions simultaneously: it focuses light from different spatial positions in the fiber core to corresponding locations on the detector, enables parallel measurement across the entire core, and eliminates the need for separate alignment mechanisms. This multi-functionality reduces overall system complexity.
3Loss of information
If sequential scanning measurement is performed, then detailed modal delay structure can be characterized, but the process is laborious and limited to laboratory settings
Solution Approach 1:
The patent enables field testing by transitioning from sequential scanning to parallel optical measurement. The lens array captures the entire fiber core output simultaneously in a single measurement, providing complete modal delay structure characterization without requiring laborious scanning procedures or controlled laboratory environments.
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 reduces testing time and costs by enabling the characterization of existing optical fibers in the field, allowing them to be reused if they support higher bandwidths, thus avoiding costly replacements.
Implementation Method 1
a lens array including a plurality of optical lenses... The lens array is in an optical path between the second fiber optic connector and the image sensor
Implementation Method 2
an image sensor... receives the light emitted into the first end of the optical fiber that is output from the second end of the optical fiber... and generates image data corresponding to the light that is received by the image sensor
Data Source
AI summary
A system for testing an optical fiber includes an optical source apparatus and an optical image sensor apparatus. The optical source apparatus includes a fiber optic connector that connects to a first end of the fiber, and a light emitting device which emits light into the first end of the fiber. The optical image sensor apparatus includes a fiber optic connector that connects to a second end of the fiber, an image sensor that receives light output from the second end of the fiber and generates corresponding image data, a lens array in an optical path between the fiber optic connector and the image sensor, and a processor coupled to the image sensor. The processor, in operation, determines a set of two-dimensional positions based on the image data output from the image sensor, and determines a test result based on the set of two-dimensional positions.