Light Source Position Measurement Using Grating Shadow Patterns
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Solution Overview
Problem
Current positioning devices, such as encoders and light source measurement systems, face limitations in achieving high resolution and precision, especially in natural environments with multiple light sources, and are not cost-effective for mass production.
Innovation Solution
A measurement system using an imaging device with sensitive pixels, a component that casts a shadow (such as a grating or microlens array) to compute the three-dimensional position of light sources, leveraging repetitive patterns and distinctive elements to break precision limits and handle external illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional encoders are used to measure position with high resolution, then positioning resolution can reach 1/10 of a micron or 1/10,000 of a degree, but the system complexity increases and cost increases when multiple encoders are chained to achieve three or more degrees of freedom
Solution Approach 1:
The measurement function is segmented between a fixed component (grating or microlens array) and a movable light source. The component remains stationary while the light source moves, eliminating the need for multiple encoders and reducing system complexity while maintaining high measurement precision through optical shadow patterns
Solution Approach 2:
The mechanical encoder system is replaced with an optical measurement system using light sources, gratings, or microlens arrays that cast shadows on imaging devices. This substitution eliminates mechanical contact and reduces system complexity while achieving high precision through optical phenomena
2Adaptability or versatility
If a T-shaped device with light sources is used to measure three-dimensional position, then the system can work in space, but the measurement precision is limited to at best half a micron (wavelength level)
Solution Approach 1:
The system transitions from direct 2D sensor measurement to 3D spatial measurement by having the light source move in three-dimensional space. The shadow patterns captured at different positions and angles provide depth information, enabling precise three-dimensional positioning while achieving precision far below the wavelength limit
Solution Approach 2:
A fixed component (grating or microlens array) is introduced as an intermediary between the light source and the imaging device. This intermediary creates shadow patterns that encode positional information, allowing the system to achieve high precision measurement in three-dimensional space without being limited by direct sensor resolution
3Measurement precision
If a measurement system is designed to achieve high precision below wavelength level, then the resolution exceeds the wavelength by at least one order of magnitude, but the system becomes difficult to manufacture and not economically viable for mass production
Solution Approach 1:
The system achieves high precision not through complex manufacturing but by changing the measurement parameters - using optical shadow patterns and triangulation geometry. The grating or microlens array can be manufactured with standard precision, yet the system achieves sub-wavelength resolution through the optical measurement process itself rather than requiring sub-wavelength manufacturing 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
The system achieves a resolution exceeding the wavelength by an order of magnitude, is robust to external light sources, and is economically viable for mass production, providing precise three-dimensional positioning of light sources.
Implementation Method 1
the component casts a shadow on the imaging device
Implementation Method 2
The imaging device records the image of the shadow
Data Source
AI summary
A system measures the position of a light source in space using an imager and transparent surface with a pattern on top. The pattern consists of a repetitive pattern and a distinctive element. The system achieves sub-micron precision. It also handles the measurement of several light sources simultaneously, and the measurement of the position of a retroreflector instead of the light.