Confocal 3D Camera Optical Path Segmentation for Color Noise Reduction

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Solution Overview

Problem

Existing 3D camera systems that perform both 3D and color measurements using the same optics often suffer from light scattering and reflections, which degrade the quality of color images and interfere with 3D measurement accuracy.

Innovation Solution

A device with a confocal measurement system and optical arrangement that uses an extraction/deflecting mirror to minimize light interference between 3D and color measurement paths, allowing for a large depth of field in color measurement while maintaining 3D measurement accuracy, by extracting a minimal amount of light from the 3D measurement path and using polarization filters to block internal reflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the same optics are used for both 3D measurement and color measurement, then device complexity is reduced, but light scattering and reflections occur which degrade color image quality and interfere with 3D measurement accuracy

Engineering Contradiction:
Improveoptical path configurationVSAvoidcolor image quality and 3D measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The optical path is segmented into distinct 3D measurement and color measurement paths using beam splitters and extraction mirrors. The beam splitter separates light into different paths for 3D and color measurement, while the extraction mirror extracts only the necessary light for color measurement, leaving the main 3D measurement path unaffected. This segmentation resolves the contradiction by allowing both measurements to occur simultaneously without mutual interference.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The extraction mirror extracts a minimal amount of light from the 3D measurement path specifically for color measurement. By taking out only the necessary light portion and directing it to the color sensor, the system achieves color measurement functionality without significantly impacting the 3D measurement path, thus resolving the quality degradation issue.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If a large depth of field is used for color measurement, then color image quality is improved, but 3D measurement range is reduced

Engineering Contradiction:
Improvecolor image qualityVSAvoid3D measurement range
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The system resolves the depth of field vs. measurement range contradiction by operating in different focal dimensions. The color measurement optical path is configured with a large depth of field optimized for color capture, while the 3D measurement optical path maintains its own focal characteristics for accurate depth mapping. The beam splitter and extraction mirror enable these two different focal configurations to coexist without conflict.

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

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

This approach reduces noise in color images and enhances data quality and Z-resolution in 3D images, ensuring that 3D measurement is not substantially affected by color measurement, resulting in better image fidelity.

Implementation Method 1

an extraction/deflecting mirror disposed in a color measurement optical path for extracting a 'small' amount of light for color measurement, said small amount of light being extracted from light in a 3D measurement optical path

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

using polarization filters to block internal reflections

Methodology Applied
Scientific EffectPolarization: Polarisation

Data Source

PatentEP3685118B1Device and method for determining surface topology and associated color
Publication Date: 2022.06.22 DENTSPLY SIRONA INC
  • EP3685118B1 patent drawingFigure 1
  • EP3685118B1 patent drawingFigure 2
  • EP3685118B1 patent drawingFigure 3

AI summary

A device and method and system for utilizing confocal measurement and an optical arrangement to produce 3D color images. A color measurement optical path and a 3D measurement optical path may coincide at least at an object side of the device, and a minimal amount of light is extracted from a monitoring beam for color measurement without affecting 3D measurement.