Conical-Mirror Hole Imaging for Full 360-Degree Inspection

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Solution Overview

Problem

Existing methods for inspecting holes in composite or metallic materials, such as those used in aerospace manufacturing, are limited by the inability to produce a full 360-degree planar image of a hole and often require manual or statistical inspection, which is time-consuming and lacks precision.

Innovation Solution

An optical instrument with a conical mirror is used to scan along the Z-axis of a hole, capturing 360-degree sub-images that are then mathematically transformed into planarized images, allowing for comprehensive inspection of hole conditions, including diameter and surface roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If standard microscopes are used for optical imaging of holes, then the imaging process is simple, but the field of view is narrow and only shallow-depth images can be acquired at offset angles

Engineering Contradiction:
Improveimaging system complexityVSAvoidfield of view
Core Design Contradiction:
Device complexityVSArea of moving object

Solution Approach 1:

The patent employs a conical mirror with a specific half-angle (e.g., 45 degrees) to reflect light from the hole axis radially outward, capturing 360-degree circumferential views. This conical geometry enables the system to achieve a complete circular field of view at the hole's opening while maintaining a compact imaging apparatus.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent transitions from traditional axial imaging to radial imaging by using a conical mirror that captures light from all angular directions around the hole axis. This dimensional transformation enables simultaneous acquisition of 360-degree circumferential information in a single image, overcoming the narrow field-of-view limitation of conventional microscopes.

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

2Device complexity

If conventional optical imaging is used, then the equipment is simple, but full 360-degree planar images cannot be produced in a single focal plane

Engineering Contradiction:
Improveoptical system complexityVSAvoidcompleteness of hole image
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The conical mirror's curved reflective surface is specifically designed to map the three-dimensional hole geometry onto a two-dimensional circular image plane. The mirror's half-angle is optimized to ensure that light rays from all circumferential positions converge properly, enabling complete 360-degree coverage without information loss.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent creates an optical copy of the hole's internal geometry by reflecting light off the conical mirror onto the image sensor. This optical copying process captures the complete circumferential morphology of the hole in a single focal plane, producing a planar representation that preserves all spatial information.

Inventive Principle:
Principle #26Copying

3Device complexity

If manual inspection with hole diameter probes is used, then the equipment is simple, but inspection is time-consuming and lacks precision

Engineering Contradiction:
Improveinspection equipment complexityVSAvoidinspection speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent replaces manual mechanical probing with an automated optical imaging system. The conical mirror-based optical instrument captures complete hole geometry information through light reflection, eliminating the need for physical probe insertion and manual measurement, thereby significantly increasing inspection speed and precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical system creates a digital copy of the hole's geometric features through reflected light patterns. This optical copying enables automated image processing and measurement algorithms to extract dimensional data rapidly and precisely, replacing time-consuming manual measurement procedures.

Inventive Principle:
Principle #26Copying

4Device complexity

If statistical inspection of sampled holes is used, then the equipment is simple, but inspection precision and reliability are reduced

Engineering Contradiction:
Improveinspection system complexityVSAvoidhole dimension measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent enables comprehensive inspection of every hole in a workpiece by providing complete 360-degree imaging capability. This preliminary complete capture of all hole geometries allows for 100% inspection coverage, eliminating the need for statistical sampling and ensuring every hole meets specifications with high precision.

Inventive Principle:
Principle #10Preliminary 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 method provides a thorough and efficient optical inspection of holes, enabling full 360-degree viewing and assessment of hole dimensions and surface quality in a single scan, overcoming the limitations of conventional imaging techniques.

Implementation Method 1

an optical subassembly supported by the housing and configured so that light from the light source impinges on the conical mirror and is reflected radially outward by the conical mirror and light propagating radially inward and impinging on the conical mirror is directed onto the image sensor

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3745118B1Optical imaging and scanning of holes
Publication Date: 2025.10.01 THE BOEING CO
  • EP3745118B1 patent drawingFigure 1
  • EP3745118B1 patent drawingFigure 2
  • EP3745118B1 patent drawingFigure 3

AI summary

Methods and apparatus for optical imaging and scanning of holes (6) machined, drilled or otherwise formed in a substrate (2) made of composite or metallic material. The method utilizes an optical instrument (50) for imaging and scanning a hole in combination with an image processor configured (e.g., programmed) to post-process the image data to generate one complete planarized image without conical optical distortion. The optical instrument includes an optical microscope (10) with confocal illumination and a conical mirror (8) axially positioned to produce a full 360-degree subimage with conical distortion. In the post-processing step, a mathematical transformation in the form of computer-executable code is used to transform the raw conical sub-images to planar sub-images. The planarized sub-images may be stitched together to form a complete planarized image of the hole.