Geometric Measurement System for Curved Surfaces
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Solution Overview
Problem
Existing measurement systems face difficulties in accurately measuring highly curved and optically transmissive objects due to challenges in projecting and collecting light uniformly across complex surfaces, distinguishing between reflections from different surfaces, and potential damage to the object during measurement.
Innovation Solution
A method and system that adjust the positional relationship between a light source and the object's surface to illuminate only a subregion, using a wavefront sensor to determine the geometric characteristics of the first surface while blocking light from the second surface, and stitching together wavefronts from multiple subregions to construct a comprehensive surface map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high numerical aperture lenses are used to project and collect light from highly curved surfaces, then measurement accuracy is improved, but device complexity and difficulty of operation increase
Solution Approach 1:
The patent divides the measurement process into multiple sequential measurements of different subregions rather than attempting to measure the entire highly curved surface simultaneously. Each subregion is measured with a wavefront sensor, and the measurements are stitched together to form a complete surface map. This segmentation approach eliminates the need for high numerical aperture lenses while achieving comprehensive surface characterization.
Solution Approach 2:
The patent transitions from attempting to capture the entire highly curved surface in a single measurement to measuring multiple subregions sequentially and combining them. This dimensional approach to measurement space allows standard optical components to be used while still achieving complete surface coverage through computational stitching of multiple measurements.
2Productivity
If light is projected onto the entire surface at once, then measurement speed is improved, but measurement precision deteriorates due to mixed reflections from multiple surfaces
Solution Approach 1:
The patent segments the measurement process into multiple sequential measurements of different subregions. By measuring one subregion at a time, reflections from other surfaces are eliminated, allowing precise measurement of each region. The segmented measurements are then computationally combined to achieve complete surface coverage with high precision.
3Productivity
If the entire surface is measured in a single measurement, then productivity is improved, but measurement precision deteriorates due to limited dynamic range
Solution Approach 1:
The patent divides the surface into multiple subregions that are measured sequentially. Each subregion measurement remains within the dynamic range of the instrument, ensuring high precision. The segmented measurements are then stitched together computationally to produce a complete surface map, achieving both precision and comprehensive coverage.
4Measurement precision
If black paint or fluid immersion is used to block reflections from unwanted surfaces, then measurement precision is improved, but object integrity is compromised
Solution Approach 1:
The patent segments the measurement into separate subregion measurements, allowing reflections from different surfaces to be temporally separated rather than spatially blocked. This eliminates the need for black paint or fluid immersion, preserving object integrity while achieving precise measurements of the surface of interest.
Solution Approach 2:
The patent uses periodic scanning to sequentially measure different subregions of the surface. By timing the measurement process to capture one subregion at a time and using the known scan trajectory, reflections from other surfaces occur at different times and can be separated in the temporal domain, eliminating the need for physical blocking methods that could damage the object.
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 accurate measurement of highly curved and optically transmissive objects by isolating and measuring individual surfaces, providing precise geometric characterizations and surface shape maps without damaging the object.
Implementation Method 1
adjusting a positional relationship between a first surface of the object and a light source to illuminate only a subregion of the first surface of the object, whereby a portion of light illuminating the subregion of the first surface of the object passes through the object to the second surface of the object
Implementation Method 2
determining a wavefront of light received from the subregion of the first surface with a wavefront sensor
Implementation Method 3
an optical system adapted to deliver light from the light source to only a subregion of the first surface to be measured of the object, and to deliver light from the subregion of the first surface to be measured of the object to the wavefront sensor
Implementation Method 4
wherein the optical system includes a spatial filter adapted to block a majority of light from the second surface of the object not being measured from reaching the wavefront sensor
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
A geometric measurement system is adapted to precisely measure one or more surfaces of objects such as corneas, molds, contact lenses in molds, contact lenses, or other objects in a fixture. The geometric measurement system can employ one or more of three possible methods of measurement: Shack-Hartmann wavefront sensing with wavefront stitching; phase diversity sensing; and white light interferometry.