Optical 3D Measuring Device with Electronic Pattern Switching

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Solution Overview

Problem

Existing optical 3D measurement devices using mechanically driven aperture means for generating time-varying patterns often result in measurement errors due to mechanical limitations.

Innovation Solution

A device employing a confocal measurement method with alternating checkerboard-shaped projection patterns, using electronically controlled light sources and beam splitters to project patterns onto an object, allowing for precise depth information determination without mechanical means, enabling high-frequency pattern switching and improved resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanically driven aperture means are used to generate time-varying patterns, then pattern projection is achieved, but measurement errors occur due to mechanical limitations

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmeasurement reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces mechanically driven aperture means with electronically controllable light sources (LEDs or laser diodes) that can be alternately switched on and off. This electronic control system eliminates mechanical moving parts, thereby removing the source of mechanical errors and improving both measurement precision and reliability.

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

2Productivity

If mechanically driven aperture means are used to switch patterns, then pattern variation is achieved, but switching frequency is limited by mechanical constraints

Engineering Contradiction:
Improvemeasurement speedVSAvoidpattern switching frequency
Core Design Contradiction:
ProductivityVSSpeed

Solution Approach 1:

By substituting mechanical aperture switching with electronic control of light sources, the system achieves much higher switching frequencies limited only by electronic response times rather than mechanical inertia. This dramatically increases the pattern switching frequency and overall measurement productivity.

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

Solution Approach 2:

The patent employs periodic alternation of the first and second light sources to project different patterns (e.g., checkerboard patterns with different phases) onto the object. This periodic switching enables time-multiplexed projection of multiple patterns, increasing the effective data acquisition rate and measurement speed.

Inventive Principle:
Principle #19Periodic action

3Measurement precision

If single pattern projection is used, then simple optical setup is maintained, but depth information resolution is insufficient

Engineering Contradiction:
Improvedepth information resolutionVSAvoidoptical system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the illumination function into two separate light sources (first light source and second light source), each projecting a distinct pattern (first pattern and second pattern) onto the object. By segmenting the illumination into multiple independent sources, the system captures different depth information from each pattern, thereby improving depth resolution while keeping each individual optical path relatively simple.

Inventive Principle:
Principle #1Segmentation

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 eliminates measurement errors associated with mechanical systems, enhances measurement speed, and improves the resolution of 3D data sets by determining depth information based on contrast and sharpness analysis, allowing for more accurate and efficient optical 3D imaging.

Implementation Method 1

the first projection beam of the first pattern and the second projection beam of the second pattern are deflected by means of a first beam splitter in a common illumination direction towards the object

Methodology Applied
Scientific EffectBeam splitting: Reflection

Implementation Method 2

the imaging optics are controlled and adjusted in such a way that a sharp focal plane is changed step by step along an optical axis of the device

Methodology Applied
Scientific EffectFocusing: Focusing

Implementation Method 3

the first pattern and the second pattern are reflected back from the object as observation beams and are recorded by means of the recording means

Methodology Applied
Scientific EffectOptical detection: Reflection

Data Source

PatentEP3298346B1Device for optical 3D measuring of an object
Publication Date: 2024.07.31 SIRONA DENTAL SYSTEMS GMBH CORP LEGAL
  • EP3298346B1 patent drawingFigure 1
  • EP3298346B1 patent drawingFigure 2~3
  • EP3298346B1 patent drawingFigure 4~6

AI summary

The invention relates to a device for optical 3D measurement of an object (2) by using an optical deep-scanning measuring method, comprising at least two light sources (3, 4), at least two optical means (5, 6) for generating structured patterns (30, 34) and at least one receiving means (7), wherein by means of a first optical means (5) a first pattern (30) is generated and is projected as a first projection beam (13) onto the object (2) to be received, wherein by means of a second optical means (6) a second pattern (14) is generated and is projected as a second projection beam (14) onto the object (2) to be received, wherein the imaging optics (8) is controlled and adjusted such that a sharp focal plane (18) is changed in steps along an optical axis (24) of the device. The device is formed such that the first light source (3) and the second light source (4) are alternately switched on by means of a controller (23), wherein the first pattern (30) and the second pattern (34) are projected alternately onto the object (2), wherein the first projection beam (13) of the first pattern (30) and the second projection beam (14) of the second pattern (34) can be deflected by means of a first beam splitter (9) in a common illumination direction (15) towards the object (2).