Confocal Measurement Device Optical Coupler Design
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Solution Overview
Problem
Confocal measurement devices face challenges in achieving high accuracy for position detection due to chromatic aberration and transmission characteristics when using optical fiber cables with small core diameters, leading to difficulties in detecting wavelength peaks and measuring object positions effectively.
Innovation Solution
A confocal measurement device design that incorporates a filter type or spatial optical system type optical coupler, which brings the first and second transmission waveforms close to each other, utilizing optical fiber cables with a core diameter ranging from 5 to 25 µm, and includes a diffraction lens to cause chromatic aberration, enhancing detection accuracy by reducing distortion and wavelength dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the core diameter of the optical fiber cable is decreased to sharpen the wavelength peak, then the detection accuracy is improved, but the transmission characteristics deteriorate and the wavelength peak cannot be easily detected
Solution Approach 1:
The patent optimizes the core diameter parameter of the optical fiber cable to a specific range (5-25 µm) that balances transmission characteristics and wavelength peak sharpness. This parameter change resolves the contradiction by finding the optimal value that satisfies both detection accuracy and transmission reliability requirements.
2Device complexity
If a conventional optical coupler is used with small core diameter optical fiber cables, then the device complexity is reduced, but the measurement precision deteriorates due to poor transmission characteristics
Solution Approach 1:
The patent specifies optimal parameter ranges for the optical coupler (coupling ratio 1:99 to 4:96, insertion loss <3 dB) that work effectively with small core diameter optical fiber cables. These parameter optimizations enable the use of simpler coupler structures while maintaining high measurement precision.
3Reliability
If the core diameter of the optical fiber cable is increased to improve transmission characteristics, then the reliability is improved, but the detection accuracy deteriorates due to broader wavelength peaks
Solution Approach 1:
The patent determines the optimal core diameter range (5-25 µm) through parameter optimization, balancing the trade-off between transmission reliability and detection accuracy. This specific parameter range ensures both adequate light transmission and sufficiently sharp wavelength peaks for accurate position detection.
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 improves the detection accuracy of the measurement object's position by minimizing distortion and wavelength dependency, allowing for precise measurement of the spectrum over a wide wavelength range with reduced pinhole diameters, thereby enhancing the overall measurement precision.
Implementation Method 1
accommodates a diffraction lens causing a chromatic aberration in an optical-axis direction in the incident white light
Implementation Method 2
an optical coupler to which the first optical fiber cable, a second optical fiber cable, and a third optical fiber cable are connected
Implementation Method 3
a spectroscope that is connected to the third optical fiber cable, acquires reflected light which is reflected by the measurement object and collected by the sensor head
Data Source
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AI summary
A confocal measurement device (1) includes a light source (10) that outputs white light, an optical coupler (20), a sensor head (100) that applies light with a chromatic aberration caused therein to a measurement object (200), and a spectroscope (30) that acquires reflected light which is reflected by the measurement object (200) and measures a spectrum of the reflected light. The optical coupler (20) is a filter type coupler (22) or a spatial optical system type coupler (23) that brings a first transmission waveform when light is transmitted from a first optical fiber cable (11) to a second optical fiber cable (12) and a second transmission waveform when light is transmitted from the second optical fiber cable (12) to a third optical fiber cable (13) close to each other.