Optical Surface Scanning via Liquid Droplet Diffuse Reflection
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Solution Overview
Problem
Optical touch-free scanning methods using light section triangulation struggle with surfaces having strong mirror effects or being transparent, as perpendicular laser irradiation leads to reflection or penetration issues, resulting in incomplete data capture and reduced accuracy.
Innovation Solution
Applying a plurality of fine liquid droplets to the surface, which scatter incoming light before it hits the surface, allowing for precise diffuse reflection and enabling accurate scanning even with perpendicular irradiation, with droplet sizes smaller than the scanning resolution to maintain precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the laser light fan is arranged perpendicular to the surface to be scanned, then the ability to measure recesses and undercuts is improved, but the method fails when the surface has a strong mirror effect or is transparent
Solution Approach 1:
The patent introduces liquid droplets as an intermediary substance between the laser light and the surface to be scanned. These droplets modify the optical properties of the surface, creating diffuse reflection that enables reliable optical scanning of previously problematic reflective or transparent surfaces while maintaining the ability to measure recesses and undercuts
2Reliability
If the laser light fan is irradiated in a plane not orthogonal to the surface, then the mirror effect and transparency problems are partially circumvented, but the contour determination has errors and processing is more difficult
Solution Approach 1:
The liquid droplets serve as an optical intermediary that creates diffuse reflection, allowing the use of perpendicular irradiation geometry while maintaining measurement precision. The droplets scatter light in multiple directions, ensuring sufficient reflected light reaches the sensor while the triangulation geometry remains well-defined for accurate contour determination
3Reliability
If larger liquid droplets are used to ensure sufficient light scattering, then the diffuse reflection effect is improved, but the surface structure becomes coarser and optical scanning precision is reduced
Solution Approach 1:
The patent carefully controls the size parameter of the liquid droplets, optimizing them to be small enough (much smaller than the scanning resolution) to maintain surface smoothness and scanning precision, while still being sufficient to create the necessary diffuse reflection effect. This parameter optimization resolves the contradiction between scattering effectiveness and measurement precision
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 precise optical scanning and measurement of surface contours on both reflective and transparent surfaces by ensuring diffuse reflection across the surface, improving scanability and reducing errors, while allowing for quick evaporation of the liquid droplets post-scanning.
Implementation Method 1
The plurality of approximately lenticular or semi spherical liquid droplets on the surface reflects an incoming light beam already before impacting the transparent or reflective surface of the substrate to be scanned. Namely already at a cambered surface of the individual liquid droplet. This generates a scattering of the irradiated light in all directions.
Implementation Method 2
A method to deposit very fine liquid droplets in large numbers on a surface is precipitating the liquid on the surface from a gas phase with sufficient liquid saturation which is in particular achievable in a simple manner when the surface has a lower temperature than the liquid saturated gas.
Data Source
AI summary
In order to be able to test completely transparent surfaces (22) as well as mirror surfaces (22) with optical testing methods in which light (3) is radiated onto the surface (22) to be tested and the light reflected by the surface (22) is checked by an optical test unit (6a, b) a precipitation of moisture is generated on the surface before optical testing, wherein the precipitation is generated in the form of plural small liquid droplets (8) on the surface (22) which causes a diffuse reflection of the irradiated light.