Optical Sensor Calibration via Off-Surface Focus Positioning

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Solution Overview

Problem

Existing methods for calibrating optical sensor devices for object detection, particularly in three-dimensional coordinate measurement, face challenges in achieving precise accuracy, especially when determining the exact coordinates of an optically recorded point on a calibration object, such as a ball surface, particularly in directions perpendicular to the calibration direction.

Innovation Solution

The proposed solution involves positioning at least one focus position of the optical sensor device at a distance from the surface of a calibration object rather than directly on it. This allows for a more precise recording of the calibration object by increasing the angle of incidence of the radiation, thereby enhancing the accuracy of the calibration process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the focus position is arranged directly on the surface of the calibration object, then the coordinate determination is simplified, but the measurement precision deteriorates due to small angle of incidence

Engineering Contradiction:
Improvecoordinate determinationVSAvoidcoordinate accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

Instead of placing the focus position directly on the surface (conventional approach), the patent inverts the arrangement by positioning the focus position at a distance from the surface. This inversion allows radiation to strike the surface at larger angles and reflect back through the focus position, thereby improving measurement precision while still enabling coordinate determination through mathematical processing of the detected positions.

Inventive Principle:
Principle #13The other way round (Inversion)

2Measurement precision

If the focus position is arranged at a distance from the surface, then the angle of incidence increases and measurement precision improves, but the coordinate determination becomes more complex

Engineering Contradiction:
Improvecoordinate accuracyVSAvoidcoordinate determination process
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary element - a computer or evaluation unit - that performs mathematical processing on the detected positions of the calibration object. This intermediary handles the complexity of coordinate determination from distances measured at different angles, thereby improving measurement precision without requiring the overall system to become overly complex, as the computational task is managed by dedicated software algorithms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If radiation is directed onto the calibration object at small angles, then the setup is simpler, but the reflected radiation power decreases

Engineering Contradiction:
Improvesetup simplicityVSAvoidreflected radiation power
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent inverts the conventional small-angle setup by arranging the focus position at a distance from the surface, which naturally results in larger angles of incidence. This inversion increases the reflected radiation power that returns to the sensor, thereby reducing energy loss while still maintaining a relatively simple physical setup that can be implemented with standard optical components and computational algorithms.

Inventive Principle:
Principle #13The other way round (Inversion)

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 enables more precise calibration of optical sensor devices, reducing errors associated with direct surface positioning and improving the accuracy of coordinate determination, particularly in directions perpendicular to the calibration direction.

Implementation Method 1

radiating electromagnetic radiation along the sensor axis onto a curved surface of a calibration object and detecting radiation reflected by the calibration object

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

the sensor device is configured to emit electromagnetic radiation with at least one wavelength along a sensor axis and to focus this radiation in a focus position along the sensor axis

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP3598059B1Method and arrangement for detecting a calibrating object with an optical sensor device
Publication Date: 2025.04.09 CARL ZEISS INDUSTRIELLE MESSTECHNIKE GMBH
  • EP3598059B1 patent drawingFigure 1
  • EP3598059B1 patent drawingFigure 2~5
  • EP3598059B1 patent drawingFigure 6~6a

AI summary

The invention relates to a method for detecting a calibration object (10) with an optical sensor device (215), wherein the sensor device (215) is configured to emit electromagnetic radiation with at least one wavelength and to focus this radiation in a focus position (12) along a sensor axis (L), wherein the method comprises: - shining electromagnetic radiation along the sensor axis (L) onto a curved surface (13) of a calibration object (10), which is an outer surface of the calibration object (10), and detecting radiation that is reflected from the curved surface (13) of the calibration object (10);- Arranging the sensor device (215) and the calibration object (10) relative to each other such that the focus position (12) is arranged at a distance from the curved surface (13) and a target state is reached in which a detectable reflected radiation power of the wavelength of the electromagnetic radiation corresponding to the focus position (12) or an interference characteristic determined on the basis of the detectable reflected radiation fulfills a predetermined condition. Furthermore, the invention relates to an arrangement for optically detecting a calibration object (10).