Optical Position Measuring System Fiber Multiplexing
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Solution Overview
Problem
High-precision optical position-measuring systems face challenges in minimizing the number of illuminating and detection channels required for efficient optical coupling, leading to increased expenditure and potential interference with precise position determination due to the need for multiple fiber optics and active time-division multiplexers.
Innovation Solution
The system employs a combined time-division/detection multiplexing method with demultiplexers and multiplexers integrated into the scanning optics, using single-mode fiber optics for light sources and multimode fiber optics for detectors, reducing the number of necessary fiber optics and allowing for phase-shifted optical scanning signals to be combined into fewer detection channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple fiber optics are provided for optical coupling of additional scanning units, then measurement precision is improved through redundant scanning units, but device complexity and expenditure increase
Solution Approach 1:
Multiple scanning units are time-division multiplexed onto a single fiber optic cable. The system combines signals from multiple scanning units by sequentially activating them in time slots, allowing their outputs to be combined and transmitted through one common fiber optic connection to the evaluation unit, thereby reducing the number of required fiber optics while maintaining measurement precision
Solution Approach 2:
The scanning units are activated in periodic time slots rather than simultaneously. Each scanning unit operates in a dedicated time window, creating a periodic activation pattern that allows time-division multiplexing. This periodic action enables multiple scanning units to share a single fiber optic connection without signal interference
2Device complexity
If active time-division multiplexers are used to reduce fiber optics, then device complexity is reduced, but heat input increases which deteriorates measurement precision
Solution Approach 1:
The patent replaces active electronic time-division multiplexers with a passive optical switching mechanism. Instead of using electronically controlled switches that generate heat, the system employs optical components that redirect light paths based on the periodic activation of scanning units, eliminating the heat-generating active electronics from the optical path
Solution Approach 2:
A passive optical switching network acts as an intermediary between the scanning units and the fiber optic cable. This intermediary uses optical path routing rather than electronic switching, allowing time-division multiplexed signals to be combined and transmitted through a single fiber optic without introducing heat that would affect measurement precision
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 configuration minimizes the number of fiber optics required, reducing disturbance forces on moving tables and enabling precise position determination while maintaining high precision, even with redundant scanning units.
Implementation Method 1
using single-mode fiber optics for light sources and multimode fiber optics for detectors
Implementation Method 2
using single-mode fiber optics for light sources and multimode fiber optics for detectors
Data Source
AI summary
A position-measuring system includes a plurality of scanning units for the optical scanning of at least one measuring standard, the scanning units being coupled optically to a plurality of light sources and a plurality of detectors. Disposed between the scanning units and the detectors are a plurality of demultiplexers, via which in each case at least two scanning units are coupled to one detector.