Deflecting Mirror Position Tracking Using Reference Marks

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Solution Overview

Problem

Existing optical measuring devices face challenges in accurately determining the position of a deflection mirror relative to an image sensor without mechanical instability or additional measurement devices, especially under thermal influences or during repositioning.

Innovation Solution

Incorporating a reference mark on the deflection mirror's surface that allows the digital image sensor to capture and evaluate its position, enabling self-referencing and position determination without additional encoders or interferometers, using digital interferometry or holography to calculate the deflection mirror's position from image data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a deflecting mirror is used to adjust the observation direction independently of the installation position, then the adaptability of the measuring device is improved, but the position stability of the deflecting mirror relative to the image sensor deteriorates due to thermal influences and mechanical drift

Engineering Contradiction:
Improveobservation direction adjustmentVSAvoidposition stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The system continuously captures images of the reference mark and calculates its position to determine the current state of the deflecting mirror. This feedback information is used to correct and update the stored reference position, compensating for thermal drift and mechanical instability without requiring the mirror to be mechanically rigidly fixed

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The measuring device uses its own image sensor to detect the reference mark on the deflecting mirror, enabling the system to self-monitor and self-correct its positional drift without external intervention or additional specialized sensors

Inventive Principle:
Principle #25Self-service

2Measurement precision

If additional measurement devices such as encoders or interferometers are used to detect the position of the deflecting mirror, then the measurement precision is improved, but the device complexity increases

Engineering Contradiction:
Improveposition detection accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The digital image sensor serves dual purposes: it captures images of the scene for measurement and simultaneously detects the reference mark on the deflecting mirror for position determination. This eliminates the need for separate encoders or interferometers while maintaining measurement precision

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The functionality of position detection is merged into the existing image acquisition system. The same optical path and image sensor used for scene measurement are also used to detect the reference mark, combining multiple functions into a single integrated system

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If mechanical mounting without drift compensation is used, then the device complexity is reduced, but the reliability of position information deteriorates over time due to thermal influences

Engineering Contradiction:
Improvemounting system complexityVSAvoidposition information reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

A reference position is stored before measurement begins, establishing a baseline for comparison. This preliminary reference allows the system to detect and compensate for subsequent drift, maintaining reliability without complex mechanical mounting

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the reference mark position and compares it against the stored reference position. This feedback mechanism detects drift caused by thermal influences and enables correction, maintaining reliable position information despite simple mechanical mounting

Inventive Principle:
Principle #23Feedback

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 method allows for precise and efficient self-referencing of the deflection mirror, reducing the effort required for position detection and compensating for mechanical errors due to thermal changes or repositioning inaccuracies, enabling accurate image capture and surface measurement.

Implementation Method 1

a deflecting mirror with a surface reflecting electromagnetic radiation, wherein the deflecting mirror is configured and arranged such that, during operation of the measuring device, the deflecting mirror directs electromagnetic radiation from the scene to the image sensor

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a digital image sensor for acquiring image data of a scene

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 3

the control and evaluation device calculates a first value for the first position from a set of image data acquired by the image sensor in the first position of the deflecting mirror, either from an angular position of the reference mark relative to an axis, or from a distance of the reference mark from a reference point

Methodology Applied
Scientific EffectGeometric relationship analysis: Geometry

Data Source

PatentEP3855111B1Interferometer for digital interferometry or digital holography, using a deflecting mirror
Publication Date: 2023.11.15 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3855111B1 patent drawingFigure 1~2
  • EP3855111B1 patent drawingFigure 3
  • EP3855111B1 patent drawingFigure 4

AI summary

The present invention relates to an optical measuring device comprising a digital image sensor for acquiring image data of a scene, a deflecting mirror with a surface reflecting electromagnetic radiation, wherein the deflecting mirror is configured and arranged such that, during operation of the measuring device, the deflecting mirror directs electromagnetic radiation from the scene to the image sensor, and a control and evaluation unit, wherein the control and evaluation unit is connected to the image sensor such that, during operation of the measuring device, the control and evaluation unit receives the image data from the image sensor, wherein the image sensor is configured such that, at least in a first position of the deflecting mirror, the image sensor acquires at least a first set of image data of the scene.wherein at least one reference mark is provided on the reflective surface of the deflecting mirror and wherein the control and evaluation device is configured such that the control and evaluation device calculates a first value for the position from a set of image data acquired by the image sensor in the first position of the deflecting mirror, either from an angular position of the reference mark relative to an axis, or from a distance of the reference mark to a reference point, or from an inclination of the reference mark relative to a path of electromagnetic radiation, and links this first value with the at least one first set of image data.