Light Field Generator for Optical Profilometry
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Solution Overview
Problem
Existing optical profilometry systems face challenges in accurately measuring surfaces with sharp curvature or edges and internal surfaces due to limited light reflection, leading to measurement inaccuracies and ambiguities, particularly with narrow-band interferometric systems.
Innovation Solution
The implementation of optical angle modulation systems, such as parallax panoramagram displays and acousto-optic modulators (AOMs), which modulate light angles to improve reflection and accuracy, combined with SAW modulators that use chirped RF pulses and integrated electro-optic phase shifters for scanning and interferometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is directed at a fixed angle relative to the surface throughout the scan, then the system operation is simple, but measurement accuracy deteriorates for areas with sharp curvature or edges due to insufficient light reflection
Solution Approach 1:
The patent applies dynamics by transitioning from fixed-angle light projection to dynamic angle modulation. The light field generator modulates the projection angle of light across multiple discrete angles during scanning, enabling adequate light reflection from surfaces with sharp curvature or edges while maintaining system operational simplicity through automated angle variation.
2Measurement precision
If multiple scans with different light angles are executed and 3D maps are stitched together, then measurement accuracy for sharp edges improves, but scanning time increases significantly
Solution Approach 1:
The patent implements continuity of useful action by performing angle modulation and light field scanning in a continuous, integrated process rather than executing separate scans for different angles. The light field generator continuously varies projection angles during a single scan operation, eliminating the need for multiple discrete scans and subsequent stitching operations, thereby maintaining high scanning speed while achieving accurate measurements of sharp edges and curved surfaces.
3Measurement precision
If narrow-band light is used in interferometric systems, then measurement ambiguity is reduced, but sensing range is limited
Solution Approach 1:
The patent applies parameter changes by utilizing broad-band light in combination with angle modulation techniques. Instead of being constrained to narrow-band light, the system processes broad-band light through angle-modulated projection and light field analysis, thereby expanding the sensing range while maintaining measurement clarity through the angle-based differentiation of surface features.
4Adaptability or versatility
If broad-band light is used in interferometric systems, then sensing range is expanded, but measurement ambiguities increase
Solution Approach 1:
The patent introduces angle modulation as an intermediary mechanism that mediates between broad-band light and measurement clarity. The light field generator modulates the projection angle of broad-band light, and the analysis system uses this angle information as an intermediary parameter to disambiguate surface features, thereby maintaining measurement clarity while utilizing the expanded sensing range of broad-band light.
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 enhances measurement accuracy by ensuring more light is reflected from sharp edges and curved areas, reducing measurement ambiguities and improving the precision of 3D surface mapping, even in challenging geometries.
Implementation Method 1
light diffusely reflected from the sample is detected by a camera and captured as images
Implementation Method 2
AOMs include a piezoelectric transducer for generating an acoustic wave in or on a crystal
Implementation Method 3
surface acoustic wave (SAW) modulator, which typically uses lithium niobate (LiNbO3) crystals. These modulators receive input light from a light source and radio frequency (RF) signals from an RF source. The RF signals 'drive' or deflect the light to different angles.
Implementation Method 4
The interferometric type, in contrast, is typically based upon a Mirau interferometer
Data Source
AI summary
A system and method for metrology and profilometry using a light field generator are disclosed. For this purpose, a system such as an optical analysis system scans a sample using light, and detects light reflected off a sample in various ways. The system operates different operational modes including a backscatter intensity, a triangulation, and an interferometric mode. For this purpose, the optical analysis system includes one or more optical angle modulation systems, such as surface acoustic wave (SAW) modulators, that emit light, a sample holder, and a scanning system that scans the one or more SAW modulators relative to the sample holder. The system performs tomographic reconstructions of information generated by the scans to create 3D maps/volume datasets of the sample.