Concave Mirror Triangulation for 3D Surface Height Profiling

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Solution Overview

Problem

Existing methods for determining a three-dimensional surface height profile are imprecise due to light divergence issues, particularly in depressions, and often only detect surface points rather than the entire three-dimensional surface.

Innovation Solution

A device comprising a light source emitting divergent light, a triangulation camera, and two concave mirrors to convert divergent light into parallel light for precise reflection and detection, allowing for the capture of a complete three-dimensional surface height profile through an offset/deformed light pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If divergent light rays are used for illumination, then the light can cover a larger area of the three-dimensional surface, but the detection precision deteriorates due to light divergence in depressions

Engineering Contradiction:
Improvecoverage areaVSAvoidheight profile detection precision
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The system segments the optical path into two distinct functions: illumination (using divergent light for wide coverage) and detection (using parallel light for precise measurement). The first concave mirror directs divergent illumination light onto the surface, while the second concave mirror collects reflected light and converts it to parallel rays for accurate detection, resolving the contradiction between coverage area and measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The two concave mirrors act as intermediaries that transform the light properties. The first concave mirror serves as an intermediary to distribute divergent light across the surface area, while the second concave mirror serves as an intermediary to convert reflected divergent light back into parallel rays for precise detection by the triangulation camera.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If conventional detection methods are used, then the device structure remains simple, but the ability to capture the entire three-dimensional surface deteriorates

Engineering Contradiction:
Improvedevice structureVSAvoidheight profile information
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The system transitions from point-by-point detection to area-wide detection by using a triangulation camera with a two-dimensional matrix chip. This dimensional change allows simultaneous capture of height information across the entire three-dimensional surface in one measurement plane, preventing information loss while maintaining relatively simple device structure.

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

Solution Approach 2:

The triangulation camera with two-dimensional matrix chip serves multiple functions: it detects the position of light patterns, captures height information, and records the entire surface profile simultaneously. This multi-functionality enables complete surface capture without significantly increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If light rays diverge in depressions, then the light can reach into surface irregularities, but the detection accuracy deteriorates due to distorted light patterns

Engineering Contradiction:
Improvesurface coverageVSAvoidheight profile accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Instead of attempting to maintain divergent light throughout the detection path, the system inverts the approach: it allows divergent illumination to reach all surface areas including depressions, then uses the second concave mirror to invert the light rays back to parallel configuration before detection. This inversion strategy preserves both surface adaptability and measurement precision.

Inventive Principle:
Principle #13The other way round (Inversion)

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 effective and precise determination of the three-dimensional surface height profile, reducing interference and allowing for continuous scanning to capture the entire surface, including elevations and depressions.

Implementation Method 1

a first concave mirror configured to reflect the light emitted by the light source with divergent light rays towards the three-dimensional surface of the object and to convert the light with divergent light rays into light with parallel light rays

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a second concave mirror configured to convert the light reflected from the three-dimensional surface of the object with parallel light rays into light with convergent light rays and to focus it onto the detection device

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

a detection device comprising a triangulation camera with a two-dimensional matrix chip having a plurality of pixels, configured to detect the light reflected from the three-dimensional surface of the object as an offset/distorted light pattern

Methodology Applied
Scientific EffectTriangulation: Parallax

Data Source

PatentEP3929532B1Device for determining a height profile of an object
Publication Date: 2024.01.03 BAUMER INSPECTION
  • EP3929532B1 patent drawingFigure 1
  • EP3929532B1 patent drawingFigure 2A
  • EP3929532B1 patent drawingFigure 2B~2C

AI summary

The present disclosure relates to a device (100) for determining a height profile of a three-dimensional surface of an object (107), comprising a light source (101) configured to emit light with divergent light rays (103-1), wherein the light (103-2) is reflected from the three-dimensional surface of the object (107), a detection device (109) configured to detect the light (103-3) reflected from the three-dimensional surface of the object (107) as an offset light pattern (111), a first concave mirror (105, 105-1) configured to reflect the light emitted by the light source (101) with divergent light rays (103-1) towards the three-dimensional surface of the object (107) and to convert the light with divergent light rays (103-1) into light with parallel light rays (103-2), and a second concave mirror (105, 105-2), who is trained,to convert the light reflected from the three-dimensional surface of the object (107) with parallel light rays (103-3) into light with convergent light rays (103-4) and to focus it onto the detection device (109), and an evaluation device which is designed to determine a height profile of the three-dimensional surface of the object (107) on the basis of the offset light pattern (111) detected by the detection device (109).