Calibration-Based Aberration Correction in Optical Measuring Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing measuring machines with optical imaging systems face challenges in achieving high measurement accuracy due to aberrations, which are often minimized only for specific working distances, leading to increased measurement errors at other positions.
Innovation Solution
A method and measuring machine that utilize calibration values to minimize aberrations for a defined working position, allowing for the correction of distortions and image field curvature, enabling the camera to focus regions of interest optimally onto a 'best measurement plane' for accurate dimensional property determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the imaging optics are optimized for a specific working distance to minimize aberrations, then measurement accuracy is improved at that specific position, but measurement accuracy deteriorates at other working distances
Solution Approach 1:
The patent applies preliminary action by pre-calibrating the imaging optics at multiple different working distances before actual measurement. The system stores calibration data for each working distance and automatically selects the appropriate calibration parameters based on the target working distance, enabling accurate measurements across multiple positions without requiring re-optimization during measurement
Solution Approach 2:
The patent changes the parameter of working distance by allowing the imaging optics to operate at multiple predefined working distances, each with its own optimized calibration parameters. The system dynamically adjusts which calibration set is applied based on the selected working distance, thereby maintaining measurement accuracy across different positions
2Measurement precision
If multiple calibration values are stored for different working positions to maintain accuracy, then measurement accuracy is improved across positions, but device complexity increases
Solution Approach 1:
The patent uses copying by creating digital copies of calibration data for each working distance. Instead of physically reconfiguring the optics, the system stores multiple sets of calibration parameters (digital copies) corresponding to different working distances and loads the appropriate copy during measurement, simplifying the management of multi-position calibration
3Measurement precision
If the camera is refocused for each region of interest to optimize measurement, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent applies preliminary action by pre-determining and storing the optimal working distance and calibration parameters for each region of interest before actual measurement begins. When a measurement is requested, the system immediately retrieves the pre-calculated parameters and configures the optics accordingly, avoiding time-consuming real-time optimization during the measurement process
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 results in efficient measurement with high accuracy, reducing measurement time and costs by optimizing the positioning of regions of interest relative to the camera's focus, even when aberrations vary across different working positions.
Implementation Method 1
a camera having an image sensor and an imaging optics
Implementation Method 2
the aberrations in the image recorded by the imaging optics can be corrected by way of computation
Data Source
AI summary
A method and a measuring machine for determining dimensional properties of a measurement object each use a workpiece table and a camera having an image sensor and an imaging optics. The imaging optics exhibits aberrations and is configured to be focused on a plurality of different working positions relative to the workpiece table. The aberrations are minimized by using first calibration values provided for a defined working position. A first working distance of the camera relative to a region of interest is determined. Subsequently, the imaging optics is focused, using the first working distance and using second calibration values that represent an image field curvature of the camera, such that the region of interest is substantially brought into a defined working position. Subsequently, the image recording and image evaluation take place to determine measurement values that represent the dimensional properties of the measurement object in the region of interest.