Borescope Pattern Projector for 3D Engine Inspection
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Solution Overview
Problem
Existing borescopes face challenges in reliably determining 3-D information from low-contrast areas, leading to inadequate resolution and time-consuming methods like strip light scanning, especially when inspecting complex engine components.
Innovation Solution
A borescope with an electronic image capture unit and a pattern projector using an optically imaging light guide bundle with randomly distributed optical fibers of varying transmittance, projecting a highly asymmetrical pattern to enhance contrast and enable accurate 3-D information determination through triangulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pattern of individual points is projected onto the surface to be scanned, then 3D information can be determined through triangulation, but the resolution of the 3D data is limited and insufficient for high-precision inspection of engine blades
Solution Approach 1:
The patent applies asymmetry by using an optically imaging light guide bundle with fibers of different transmittances (some transparent, some opaque) arranged in a non-uniform pattern. This creates an asymmetrical projection pattern that provides unique reference points for triangulation, enabling both high resolution and reliable 3D information determination on low-contrast surfaces like engine blades.
2Measurement precision
If structured light scanning is used to obtain 3D information, then accurate measurements can be achieved, but the method requires the relative position to remain unchanged throughout the scan, resulting in considerable time expenditure
Solution Approach 1:
The patent applies preliminary action by pre-structuring the light guide bundle with fibers of different transmittances before inspection. This pre-configured asymmetrical pattern allows for rapid triangulation-based 3D measurement without requiring time-consuming structured light scanning sequences, enabling accurate measurements while maintaining high inspection speed even when the borescope moves relative to the workpiece.
3Measurement precision
If two image sensors are used for triangulation, then 3D information can be obtained, but individual object points cannot be identified on low-contrast surfaces, making 3D determination impossible
Solution Approach 1:
The patent applies the color changes principle by using light guide fibers with different transmittances (effectively different optical densities) to create a projection pattern with varying brightness levels. This pattern creates high-contrast reference points on low-contrast surfaces, enabling the two image sensors to clearly identify individual object points for accurate triangulation and 3D information determination.
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 reliable and high-resolution 3-D information on low-contrast surfaces, improving accuracy and speed compared to traditional methods, while maintaining a compact design suitable for aircraft engine inspections.
Implementation Method 1
which comprises an optically imaging light guide bundle made of statistically distributed optical fibers with different transmittances
Implementation Method 2
the individual optical fibers of which have at least partially different transmittances... projecting a highly asymmetrical, small-scale pattern onto the surface
Implementation Method 3
an optically imaging light guide bundle made of statistically distributed optical fibers with different transmittances, with whose input surface a light source is coupled
Implementation Method 4
the position and orientation of the image acquisition sensors relative to each other are suitable for determining 3-D information by triangulation
Data Source
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AI summary
The invention relates to a borescope (1), more particularly for borescopy inspection of aircraft engines. The borescope (1) comprises an electronic image capture unit (10) with two image capture sensors (11) as the borescope objective on the end of a shaft (3) designed for introduction into a borescope opening, wherein the position and orientation of the image capture sensors (11) relative to one another is suitable for the determination of 3-D information by triangulation. Furthermore, a pattern projector (20) is provided for projecting a pattern (50) in the common recording area of the image capture sensors (11), which projector comprises a fundamentally optically imaging optical fibre bundle (21) of statistically distributed optical fibres (22) with differing degrees of transmission, with the input face (23) of which a light source (25) is coupled and the output face (24) of which is directed towards the area covered by the image capture sensors (11).