Case Study – High Precision Sphere Measurements
- High-precision sphere measurements
- Small, fast sphere (Zygo reference sphere)
Repeatability results
- Mean = 5.60 nm rms
- Range = 0.025 nm
- Std Dev: 0.007 nm rms
Cross-test results
- Mean = 5.69 nm rms
- Difference from repeats = 0.09 nm
TS#2 - 6” F/0.8 (similar lattice)
Pixel-by-pixel subtractions
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- Performed pixel-by-pixel subtraction on average of 10 measurements
- Slightly different lattice (different level of overlap) used for the two sets of 10 measurements
- Pixel-by-pixel comparisons will give higher results than comparing rms numbers, so sub-nm results are excellent
- Difference is at noise level of Zygo interferometer
- Download a PDF of the "High Precision Spherical Measurements" Case Study