Interferometry-Based Scanning for High-Speed Metrology
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Solution Overview
Problem
Current high-speed metrology techniques in additive manufacturing are limited by the speed at which they can scan moving objects, often requiring the object to stop or using complex and costly systems, which hinders the efficiency of the printing process.
Innovation Solution
The method employs interferometry-based scanning using a frequency dispersed pulsed optical signal and a rotating polygon mirror to generate multiple scan lines on a continuously moving 3D object, allowing for the creation of a depth map while the object is being fabricated, utilizing commercially available lasers and mirrors for cost-effectiveness and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional high-speed metrology techniques are used to scan moving objects, then measurement capability is provided, but the scanning speed is limited and requires the object to stop or use complex and costly systems
Solution Approach 1:
The patent replaces complex mechanical scanning systems with a combination of pulsed laser illumination and camera-based detection. Instead of using mechanical scanners that physically move across the object, the system uses temporal sampling of light reflected from a moving object, substituting mechanical motion with optical and electronic components that achieve higher speeds without proportional increases in complexity
Solution Approach 2:
The system employs periodic pulsed laser illumination at frequencies synchronized with the object's motion or the camera's frame rate. This periodic action allows the system to capture multiple depth profiles over time and reconstruct accurate 3D measurements of moving objects, achieving high scanning speeds through temporal sampling rather than mechanical movement
2Productivity
If traditional metrology systems are used, then depth measurement is provided, but the scanning speed is insufficient for high-speed additive manufacturing processes
Solution Approach 1:
The system enables continuous depth measurement during the additive manufacturing process by using pulsed laser illumination and high-speed camera capture that operate continuously as the build platform moves. Multiple depth profiles are acquired in succession during printing, allowing real-time monitoring without interrupting the printing workflow, thus maintaining continuous productive action
Solution Approach 2:
The system creates optical copies (depth profiles and 3D reconstructions) of the building object at high speed using light reflection and camera imaging. These digital copies are generated continuously during printing, enabling measurement at speeds commensurate with printing speeds without requiring physical contact or slowing down the manufacturing process
3Speed
If complex high-speed scanning systems are implemented, then scanning speed increases, but system cost and complexity increase significantly
Solution Approach 1:
The system uses inexpensive, commercially available components including standard pulsed lasers, off-the-shelf cameras, and simple optical elements instead of expensive specialized high-speed scanners. While individual components have limited functionality, their combination achieves high-speed metrology at low cost, replacing expensive durable specialized equipment with cheaper components that work together effectively
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 high-speed metrology commensurate with printing speeds, reducing material waste and increasing efficiency by allowing continuous scanning of moving objects without the need for complex systems, while maintaining sufficient resolution and depth range for additive manufacturing applications.
Implementation Method 1
forming depth characterizations of a continuously moving three-dimensional (3D) object along respective scan lines of a plurality of scan lines on a surface of the 3D object by scanning a frequency dispersed pulsed optical signal
Data Source
AI summary
A method and an apparatus are directed to characterizing a continuously moving 3D object via interferometry-based scanning. The method includes repeatedly forming several depth characterizations of the 3D object along respective scan lines of a plurality of scan lines on the surface of the 3D object. During this scanning, the 3D object is undergoing its continuous motion. The method further includes combining the determined depth characterization along the scan lines of the plurality of scan lines to form a depth map representing at least a depth of a portion associated with a location on the surface of the 3D object in the third direction on a grid of locations arranged in the first and second directions. Forming the depth characterizations includes scanning a frequency-dispersed pulsed optical signal in a first direction across the continuously moving 3D object, said 3D object moving in a second direction substantially orthogonal to the first direction. The scanned optical signal forming scan lines on a surface of the 3D object in a third direction substantially orthogonal to the first direction and the second direction.