Deflectometry Calibration for Accurate Freeform Surface Gradients
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Solution Overview
Problem
Conventional deflectometry methods struggle with accurate calibration of geometric positions and phase offsets in measuring freeform surfaces, leading to inaccuracies in three-dimensional shape measurement.
Innovation Solution
A novel calibration method for deflectometry that calibrates the phase of the reference plane mirror and geometric positions among components, using equations to compute X-direction and Y-direction gradient components, enabling swift and accurate measurement of freeform surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional interferometry is used to measure freeform surfaces, then measurement can be performed with a reference surface, but the system becomes complex and less adaptable to arbitrary surfaces
Solution Approach 1:
The patent extracts and removes the reference surface from the measurement system, making deflectometry independent of reference surfaces. This allows the system to measure arbitrary freeform surfaces without requiring a separate reference component, thereby increasing adaptability while simplifying the overall system configuration.
Solution Approach 2:
The deflectometry system is designed to universally measure any freeform surface without requiring configuration changes or reference surfaces specific to each surface type. The system achieves multi-functionality by using a single projection-screen-camera configuration that can adapt to measure various arbitrary surfaces through mathematical reconstruction algorithms.
2Measurement precision
If conventional calibration methods are used to determine geometric positions and phase offsets, then system components can be positioned, but measurement accuracy deteriorates due to cumulative errors in gradient component calculations
Solution Approach 1:
The patent performs preliminary calibration by measuring the phase of the reference plane mirror and determining geometric positions and β parameters before actual surface measurement. This preliminary action establishes accurate baseline values that eliminate cumulative errors in subsequent gradient component calculations, thereby improving measurement precision.
Solution Approach 2:
The system uses feedback from the measured phase of the reference plane mirror to校准 geometric positions and phase offsets. By continuously referencing back to the known reference surface measurements, the system corrects calibration parameters to maintain high measurement accuracy throughout the measurement process.
3Measurement precision
If complex calibration procedures are performed to accurately determine geometric positions and phase offsets, then measurement accuracy improves, but calibration time increases
Solution Approach 1:
The patent performs necessary calibration measurements of the reference plane mirror's phase and geometric positions in advance, before actual surface measurement begins. This preliminary calibration establishes accurate baseline parameters that remain valid throughout subsequent measurements, achieving high precision without repeated time-consuming calibration cycles.
Solution Approach 2:
The system changes the calibration approach by measuring phase values and geometric parameters once during initial setup, then using these fixed parameters for all subsequent measurements. This parameter establishment method reduces calibration time while maintaining accuracy by avoiding continuous recalibration.
4Loss of information
If multiple gradient components are calculated through integration to restore three-dimensional shape, then complete surface information is obtained, but computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary calibration to accurately determine geometric positions and phase relationships before gradient calculation. By establishing accurate baseline parameters in advance, the system reduces computational complexity during the actual surface reconstruction process while maintaining complete surface information through integration of gradient components.
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
Enables precise and efficient measurement and analysis of freeform surfaces by swiftly and accurately computing gradient components through a novel algorithm, improving measurement accuracy.
Implementation Method 1
a detector that obtains an image of a deformed pattern reflected from the measurement object
Data Source
AI summary
The present disclosure relates to a method that enables easy and fast calibration of deflectometry for measuring and analyzing the shape of a measurement target with a freeform surface in which the phase of the reference plane mirror, the geometric position information among the components (screen, reference plane mirror, detector) and β from the phase offset are measured are calibrated in the calibration step before the shape measurement of the measurement object; the phase of the measurement target is measured; α is calibrated using β as a basis to compute the gradient components; and the X-direction phase (X-direction gradient component) and Y-direction phase (Y-direction gradient component) are swiftly and accurately computed through a novel algorithm.