The 2-MGEM Optical Anistropy Factor Measurement System is a normal-incidence polarization reflection microscope designed to measure the sample Mueller matrix, specifically applied to the Optical Anisotropy Factor of TRISO nuclear fuel pyrocarbon layers. Other possible materials characterization would be to measure Mueller matrix elements of other crystals, carbon compounds, and thin film coatings at normal incidence.
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Map of the Diattenuation of the TRISO |
Direction of the Principal Axis
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Cross Section of a TRISO |
| The 2-MGEM advantages |
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- No sample rotation is needed.
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2-MGEM data is taken as a function of x- and y- position, making it possible to construct an image of the various measured parameters. All the previous techniques were only able to measure at single points.
- The 2-MGEM measures 8 parameters, which then can be reduced to the diattenuation N and the principal direction
 . The quantities N and cannot be measured simultaneously using any of the older techniques.
- The 2-MGEM measures each of the 8 parameters to ~0.001; previous measurements of OPTAF were accurate to ~0.01. The 2-MGEM is 10 times more accurate. This accuracy is critical because the variations in the diattenuation from processing conditions are often as small as 0.002.
- The 2-MGEM can also measure retardation d, circular diattenuation CD and the polarization factor ß. These parameters are not measurable using the older techniques, since those techniques do not incorporate a compensating optical element.
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