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Four-step shear method for the absolute measurement of a flat surface based on phase measuring deflectometry
Applied Optics
|November 10, 2016
Summary
This study introduces a novel shearing approach for phase measuring deflectometry (PMD) to correct systematic errors. By analyzing translated and rotated measurements, it accurately reconstructs surface figures, improving optical testing precision.
Area of Science:
- Optical Metrology
- Surface Metrology
- Precision Engineering
Background:
- Phase Measuring Deflectometry (PMD) is susceptible to systematic errors.
- Accurate surface figure reconstruction is critical in optical testing.
Purpose of the Study:
- To develop a new shearing method to eliminate systematic errors in PMD.
- To reconstruct the true test surface figure with high accuracy.
Main Methods:
- A novel shearing approach involving four measurements: one normal and three with known translations/rotations.
- Utilizing three sheared wavefronts derived from the four measurements.
- Employing difference Zernike polynomial fitting and a least squares algorithm for surface reconstruction.
Main Results:
- Demonstrated and verified the proposed method through computer simulations.
- Validated the approach using experimental results.
- Analyzed error propagation from random noise and incorrect shearing values.
Conclusions:
- The proposed shearing method effectively eliminates systematic errors in PMD.
- Accurate surface figure reconstruction is achievable with the developed technique.
- The method provides a robust solution for high-precision optical surface testing.
