Intensity Modulating Element for 3D Surface Mapping

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Solution Overview

Problem

Current borescopes and endoscopes face challenges in accurately performing 3D surface mapping and dimensional measurements due to limitations in existing technologies, such as stereo viewing methods, dot projection techniques, and single line profiling, which often require significant processing, skilled operators, and are not suitable for full-field object measurements, especially in small probes where size constraints are a concern.

Innovation Solution

A borescope probe equipped with an intensity modulating element featuring a plurality of light emitters and grating elements that project fringe sets for phase-shift analysis, allowing for more accurate phase-shift analysis and enabling full-field surface mapping by altering the light distribution to create structured-light patterns for precise measurement and imaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If stereo viewing or dot projection methods are used to obtain 3D data, then 3D surface mapping capability is provided, but the device complexity and processing requirements increase significantly

Engineering Contradiction:
Improve3D surface mapping capabilityVSAvoidprocessing requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses periodic fringe patterns (repeating sinusoidal or square wave patterns) projected onto the surface instead of random dot patterns. These periodic patterns enable simpler correlation-based phase measurement algorithms, reducing computational complexity while maintaining full-field 3D mapping capability. The regular structure of the fringes allows for efficient phase unwrapping and surface reconstruction.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent varies the phase shift parameter of the projected fringe patterns across multiple projections (e.g., 0, 90, 180, 270 degrees). By changing only the phase parameter while keeping the pattern structure identical, the system enables accurate surface mapping through phase demodulation algorithms that are computationally less intensive than stereo matching, thus reducing processing requirements.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a single line profile is projected for measurement, then processing is simplified, but the ability to obtain full-field surface mapping is limited

Engineering Contradiction:
Improveprocessing simplicityVSAvoidfull-field surface mapping
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent extends the measurement from a single line (1D) to a two-dimensional full-field pattern by projecting fringe patterns that cover the entire field of view. The fringe patterns consist of multiple lines arranged in a grid or array, allowing simultaneous measurement of all points across the surface rather than requiring sequential line scanning, thus achieving full-field mapping with simplified processing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent pre-structures the light pattern into regular fringe patterns before projection, with known spatial frequencies and phases. This preliminary structuring of the light field enables direct phase calculation from captured images without requiring complex post-processing or sequential scanning, achieving both full-field coverage and processing simplicity simultaneously.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If multiple fringe sets with physical offsets are used to determine absolute phase, then measurement accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improveabsolute phase determinationVSAvoidmultiple fringe sets requirement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses periodic fringe patterns with well-defined spatial frequencies and phases. By projecting a small number of phase-shifted patterns (typically 3-4) with identical periodic structures but different phase offsets, the system can determine absolute phase through standard phase-shifting algorithms, avoiding the need for complex multiple-frequency or multi-set approaches while maintaining measurement accuracy.

Inventive Principle:
Principle #19Periodic action

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 solution provides accurate and efficient 3D surface mapping and dimensional measurements with improved brightness and contrast, reducing the need for complex equipment and skilled operators, and is suitable for small probes, enabling the capture of detailed surface information with high precision.

Implementation Method 1

at least one intensity modulating element comprising a plurality of columns of a plurality of grating elements

Methodology Applied
Scientific EffectLight modulation through grating elements: Diffraction Grating

Data Source

PatentEP2520217B1Fringe projection system for a probe with intensity modulating element suitable for phase-shift analysis, and intensity modulating element
Publication Date: 2020.08.12 GENERAL ELECTRIC CO
  • EP2520217B1 patent drawingFigure 1
  • EP2520217B1 patent drawingFigure 2~3
  • EP2520217B1 patent drawingFigure 4~5

AI summary

An intensity modulating element for a probe having a plurality of light emitters for phase-shift analysis and measurement is disclosed. The intensity modulating element comprises a plurality of columns of a plurality of grating elements formed by two opposing patterns to project a plurality of fringe sets comprising a structured light pattern.