F-P Sensor Probe Absolute Distance Measurement
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Solution Overview
Problem
Current non-contact absolute distance measurement technologies, such as laser triangulation reflective sensors and capacitive sensors, face challenges in achieving high precision, repeatability, and resolution, especially in applications like semiconductor processing and super-smooth surface topography detection, due to calibration requirements and susceptibility to parasitic capacitance and thermal drift.
Innovation Solution
The development of an optical fiber F-P sensor probe structure, comprising a first N+1-core multimode optical fiber probe, an optical fiber sleeve, and a reference lens, which uses Fabry-Perot interferometry to measure absolute distances without calibration, with a metal film layer and quartz glass reference lens for enhanced reflectivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spectral confocal sensors are used to achieve good repeatability during light interruption, then measurement repeatability is improved, but measurement resolution deteriorates
Solution Approach 1:
The patent replaces traditional mechanical/optical detection systems with an optical fiber-based F-P interferometer system. This substitution enables direct absolute distance measurement through optical interference patterns, achieving both high repeatability during light interruption and high measurement resolution simultaneously, as the optical interference method is inherently more precise than mechanical positioning methods.
Solution Approach 2:
The patent changes the measurement parameter from indirect mechanical position detection to direct optical interference pattern analysis. By measuring the phase shift in optical interference patterns, the system achieves absolute distance measurement with high resolution and maintains repeatability during light interruption, resolving the contradiction between these two performance parameters.
2Measurement precision
If capacitive sensors are used to achieve direct measurement of absolute distances, then measurement capability is improved, but the sensors become susceptible to parasitic capacitance and thermal drift
Solution Approach 1:
The patent replaces capacitive sensing with optical fiber-based F-P interferometry. This substitution eliminates parasitic capacitance effects entirely, as the measurement is based on optical interference patterns rather than electrical capacitance changes. The optical method is also inherently immune to thermal drift, providing stable absolute distance measurements.
Solution Approach 2:
The patent introduces optical interference patterns as an intermediary measurement medium between the sensor and the target object. This intermediary approach allows absolute distance measurement without direct electrical contact, thereby eliminating parasitic capacitance and thermal drift effects that plague capacitive sensors.
3Measurement precision
If laser triangulation reflective sensors are used to achieve high-precision distance measurement, then measurement precision is improved, but calibration is required and repeatability during light interruption deteriorates
Solution Approach 1:
The patent replaces laser triangulation with optical fiber-based F-P interferometry. This substitution eliminates the need for calibration by using the optical interference pattern itself as the measurement basis. The system achieves high precision distance measurement while maintaining repeatability during light interruption, as the interference pattern provides continuous reference information.
Solution Approach 2:
The patent implements a self-calibrating measurement system where the F-P interferometer uses its own optical interference patterns as the reference for measurement. This self-service approach eliminates external calibration requirements and maintains measurement repeatability during light interruption, as the system continuously references its own interference pattern.
4Adaptability or versatility
If multiple optical fibers are arranged annularly around the central fiber to improve measurement coverage, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the F-P interferometer system to perform multiple functions using the same optical fiber arrangement. The annular arrangement of optical fibers serves both as the interferometer arms and as the light collection system, enabling comprehensive measurement coverage without proportionally increasing device complexity. The system can measure absolute distance, reflectivity, and other optical properties simultaneously.
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 solution enables high-precision, high-resolution, and repeatable non-contact absolute distance measurement, overcoming the limitations of existing technologies by providing accurate measurements without calibration and minimizing thermal drift effects.
Implementation Method 1
The development of an optical fiber F-P sensor probe structure, comprising a first N+1-core multimode optical fiber probe, an optical fiber sleeve, and a reference lens, which uses Fabry-Perot interferometry to measure absolute distances without calibration
Implementation Method 2
the film layer inside the window is a metal film layer with a transmittance of 40%+5% and a reflectivity of 15%+5%
Data Source
AI summary
Provided are an F-P sensor probe, an absolute distance measurement device, and an absolute distance measurement method, which relate to the field of non-contact absolute distance measurement technologies. This structure includes a first N+1-core multimode optical fiber probe (9), an optical fiber sleeve (10), an imaging lens group (11), and a reference lens (12), wherein: the first N+1-core multimode optical fiber probe (9), the imaging lens group (11), and the reference lens (12) are sequentially fixed inside the optical fiber sleeve (10) along a direction of the F-P sensor probe toward a sample (8); and the first N+1-core multimode optical fiber probe (9) includes N first multimode optical fibers (16) and one second multimode optical fiber (17), where N≥2, and the N first multimode optical fibers (16) are arranged around the second multimode optical fiber (17).