Non-Contact Optical Sensor for Sub-Pixel Surface Motion Detection
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Solution Overview
Problem
Current technologies for determining an object's position, motion, and resonances are limited by the need for visual contrast typically associated with edges, making it difficult to analyze surfaces without physical contact and with sufficient precision.
Innovation Solution
The use of optical sensors, including single-element photodiode sensors and multiple-element video camera systems with high dynamic range and diffraction-limited imaging, allows for non-contact measurement of surface motions with sub-pixel precision by analyzing light modulation due to changes in object properties, such as position, inclination, and reflectivity, without requiring physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors analyze light modulation from object surfaces, then measurement precision is improved, but the system requires high dynamic range and low-noise sensors increasing device complexity
Solution Approach 1:
The patent divides the measurement task into two distinct sensor pathways: (1) high dynamic range, low-noise photo sensors for detecting sub-pixel precision surface motions, and (2) standard video camera systems for broader structural analysis. This segmentation allows each sensor type to be optimized for its specific function, achieving high measurement precision without requiring all components to be complex high-precision devices.
Solution Approach 2:
The system extends measurement capability from traditional edge detection (1D position) to surface analysis by adding temporal and spectral dimensions. By analyzing light modulation across multiple dimensions (spatial, temporal frequency, and intensity), the system achieves sub-pixel precision measurement of surface motions without requiring proportionally increased sensor complexity.
2Measurement precision
If the system uses high dynamic range photo sensors for sub-pixel precision measurement, then measurement sensitivity is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies high dynamic range, low-noise photo sensors selectively to specific measurement points where sub-pixel precision is critical, rather than requiring all sensors in the system to be high-specification devices. This local quality approach ensures measurement sensitivity where needed while controlling overall device complexity through the use of standard sensors for other functions.
3Adaptability or versatility
If the system analyzes object surfaces instead of edges, then applicability is improved, but measurement precision deteriorates due to lack of visual contrast
Solution Approach 1:
The system overcomes the lack of visual contrast on surfaces by changing the measurement parameters from spatial position (edge detection) to temporal frequency analysis. By detecting periodic surface motions and vibrations through time-domain analysis of light modulation, the system achieves precise surface measurement without relying on high spatial contrast, thereby enabling versatile surface analysis while maintaining measurement precision.
4Measurement precision
If existing non-contact systems use laser Doppler vibrometers, then measurement precision is improved, but the system requires physical markers on the object increasing ease of operation complexity
Solution Approach 1:
The system employs the object's own surface properties and ambient light reflections to generate measurable signals, eliminating the need for external markers. By detecting light modulation caused by surface motions themselves, the object effectively measures its own motion without requiring external assistance or modification, thereby improving ease of operation while maintaining 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 approach enables the detection of small surface motions, such as 10 nanometers, and provides sensitive, non-contact assessment of structural integrity and motion in various applications, including bridges, machinery, and biomedical monitoring, identifying failures not visible through traditional edge detection methods.
Implementation Method 1
The amplitude of the detected light is modified by changes in the properties of the object element due to its position, inclination, transmissivity, reflectivity, and texture
Implementation Method 2
Some embodiments utilize high dynamic range, low-noise photo sensors, and diffraction-limited imaging, in order to obtain desired sensitivity to positioning of features in the object
Data Source
AI summary
A non-contact sensing system for measuring and analyzing an object's position, motion, and/or resonance utilizes optical capturing of image features, data extraction, and signal processing to determine changes in the object's motion or position according to changes in signals, which are associated with the excitation of photons due to the object's motion.