Computer-aided high-accuracy testing of reflective surface with reverse Hartmann test.

Area of Science:

• Optical Engineering
• Metrology
• Surface Science

Background:

• Deflectometry offers high dynamic range for surface testing, but calibration remains a critical challenge.
• Accurate calibration is essential for minimizing systematic errors in reflective surface testing, particularly with off-axis configurations.

Purpose of the Study:

• To propose a computer-aided testing method using reverse Hartmann deflectometry for high-accuracy reflective surface testing.
• To develop a robust calibration method addressing system geometry uncertainties for improved measurement accuracy.

Main Methods:

• Utilized reverse Hartmann deflectometry with fringe illumination for virtual 'null' testing via ray tracing.
• Implemented a computer-aided reverse optimization with iterative ray tracing for system calibration.
• Validated the method through computer simulations and experimental measurements.

Main Results:

• Achieved high measurement accuracy for reflective surfaces, comparable to interferometric methods.
• Demonstrated the feasibility of the proposed method even with significant system geometry calibration errors.
• Successfully addressed uncertainties related to system geometry calibration in deflectometry.

Conclusions:

• The proposed computer-aided reverse optimization calibration method enhances the accuracy of deflectometry for reflective surface testing.
• This approach provides a feasible solution for achieving high-precision measurements, overcoming limitations of traditional calibration techniques.
• The method offers a viable alternative to interferometry for demanding optical metrology applications.