Available Technology

SCANNING MICROWAVE ELLIPSOMETRY, PROCESS FOR MAKING AND USE OF SAME

Application Title (SCANNING MICROWAVE ELLIPSOMETER AND PERFORMING SCANNING MICROWAVE ELLIPSOMETRY)

This invention is scanning microwave ellipsometry. It contains a test head that rotates the electric microwave field relative to the sample without rotating the sample; a test head mounted onto a 6-axis robotic arm; and an algorithm that fits the microwave ellipsometry data. This a new tool and method to characterize carbon fiber alignment and measure materials for inline quality assurance or for verification of alignment in 3D parts. This implementation uses a polarized electric microwave field and measures the reflection of that field off a sample under test as a function of angle. The resulting reflected power plotted versus measured angle on a polar plot can have an elliptical shape. Leveraging this idea, we designed a test head that rotates the electric microwave field relative to the sample without rotating the sample. To raster the test head over a sample, we placed the test-head on a 6-axis robotic arm. To use this implementation, we wrote an algorithm that fit the microwave ellipsometry data. The algorithm produces four discrete measurands that can be plotted as a function of position in three-, two-, or one-dimensions. The measurands are the maximum value, the minimum value, the alignment value, and the orientation value.

Patent Abstract: 

New strong, light, and compact formed carbon fiber components require shorter, higher-aspect ratio carbon fibers. Shorter carbon fibers must be aligned to realize the desired tensile strength. Before this invention, industry lacked a tool to characterize carbon fiber alignment for inline quality assurance or for verification of alignment in 3D parts. This invention solves that problem through the implementation of scanning microwave ellipsometry. The implementation uses a polarized electric microwave field and measures the reflection of that field off a sample under test as a function of angle. The resulting reflected power plotted versus measured angle on a polar plot can have an elliptical shape. Leveraging this idea, NIST designed a test head that rotates the electric microwave field relative to the sample without rotating the sample. To raster the test head over a sample, NIST placed the test head on a 6-axis robotic arm. To use this implementation, NIST wrote an algorithm that fit the microwave ellipsometry data. The algorithm produces four discrete measurands that can be plotted as function of position in three-, two-, or one- dimension. The measurands are the maximum value, the minimum value, the alignment value, and the orientation value. While the target application is directed at carbon fiber, scanning microwave ellipsometry to industrial materials is broadly applicable to any use case where large-scale imaging of material properties is useful.

Benefits 

Current practice is to image the material on a light table. Light table imaging does not provide quantitative data for analysis, only relative information. Image processing techniques average over the image or segment the image. Light table imaging fails when the host matrix is not optically transparent or if the material is too dense.

Inventors: 

Long, Christian John; Orloff, Nathan Daniel; Garboczi, Edward Joseph; Basta, Nina Popovic

Patent Number: 
Pending (Serial Number 16/864,466 Publication Number 2020/0348224 A1)
Technology Type(s): 
Advanced Communications, Networking, and Physics
Internal Laboratory Ref #: 
19-040US1
Patent Status: 
Published Patent Application
Phone: 
301-975-2573
Email: 
tpo@nist.gov
Lab Representatives
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