Speckle Pattern Surface Slope Sensing
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Solution Overview
Problem
Current imaging technologies face challenges in accurately determining the properties of an object's surface with high precision and efficiency, particularly in correcting for errors introduced during measurement, and often suffer from limitations such as shadowing and surface-access issues.
Innovation Solution
A surface-slope sensing system that uses coherent radiation at multiple wavelengths to create speckle patterns, determining shifts between these patterns to calculate surface slope information, allowing for high-precision measurements without the constraints of triangulation-based approaches and applicable across various measurement scales from microscopic to laser-radar applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation-based approaches are used for surface measurement, then measurement capability is achieved, but shadowing and surface-access issues occur
Solution Approach 1:
The patent replaces triangulation-based mechanical/optical measurement systems with a speckle pattern analysis system using coherent radiation. The system illuminates the surface with coherent light and analyzes the resulting speckle patterns to determine surface properties, eliminating the need for complex geometric triangulation and avoiding shadowing issues.
Solution Approach 2:
The patent utilizes changes in speckle pattern parameters (such as pattern shift, correlation, or statistical properties) in response to surface slope variations. By measuring how the speckle pattern parameters change with surface orientation, the system can determine surface properties without the geometric constraints of triangulation methods.
2Measurement precision
If conventional imaging technologies are used, then surface properties can be determined, but high precision and error correction are difficult to achieve
Solution Approach 1:
The patent employs feedback through autocorrelation analysis of speckle patterns. The system compares the speckle pattern at a given wavelength with patterns at reference wavelengths, using the correlation feedback to precisely determine surface slope information and correct for measurement errors.
Solution Approach 2:
The patent uses speckle pattern analysis as a universal measurement approach that can determine various surface properties (slope, shape, texture) through a single measurement technique. The same speckle pattern data serves multiple measurement functions, eliminating the need for separate correction procedures for different error types.
3Measurement precision
If multi-wavelength speckle patterns are analyzed, then surface slope information with high precision is obtained, but measurement and processing complexity increases
Solution Approach 1:
The patent segments the measurement process by analyzing speckle patterns at discrete wavelengths separately. The system measures at multiple wavelengths and processes each wavelength's speckle pattern independently through autocorrelation, then combines the results to determine surface slope information. This segmentation simplifies the processing of multi-wavelength data compared to simultaneous analysis.
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
Enables high-precision surface profile measurements with enhanced resolution and cost-effectiveness, overcoming the limitations of existing methods by accurately determining surface slope information through speckle pattern analysis, suitable for diverse applications including biometrics and industrial inspection.
Implementation Method 1
obtain a first defocused image of the neighborhood illuminated with the first wavelength where the first defocused image comprises a first speckle pattern
Data Source
AI summary
A system that incorporates teachings of the present disclosure may include, for example, an apparatus that includes a processor coupled with a memory where the processor is operable to obtain a first speckled pattern of a first defocused image of a neighborhood of a location on an object, to obtain a second speckled pattern of a second defocused image of the neighborhood, to determine a shift between the first and second speckle patterns, and to calculate slope information of a surface profile at the location based on the determined shift. Other embodiments are disclosed.