Nonnull testing of rotationally symmetric aspheres: a systematic error assessment

Area of Science:

• Optical Engineering
• Metrology
• Surface Characterization

Background:

• Testing rotationally symmetric aspheres typically requires a null optic, adding complexity and cost.
• Strongly curved wavefronts generated by aspheres pose challenges for conventional testing methods.

Purpose of the Study:

• To propose and validate a novel optical setup for testing rotationally symmetric aspheres without a null optic.
• To demonstrate the capability of Shack-Hartmann sensor algorithms to handle steep wavefront slopes in asphere testing.

Main Methods:

• Development of a new optical configuration designed to transfer strongly curved wavefronts.
• Utilizing Shack-Hartmann sensor algorithms for wavefront analysis.
• Systematic error analysis and derivation of error functionals.
• Validation through extensive simulations.

Main Results:

• The proposed optical setup successfully transfers strongly curved wavefronts from aspheric surfaces.
• Shack-Hartmann sensor algorithms demonstrated robustness in handling wavefront slopes up to approximately 110λ/mm.
• Systematic errors were analyzed, and functionals were derived and validated via simulation.
• Maximum residual errors in simulations were below λ/500 (peak-to-valley).

Conclusions:

• The developed optical setup offers a viable, null-optic-free method for testing rotationally symmetric aspheres.
• The approach ensures high accuracy, with minimal residual errors, suitable for precision optical metrology.
• This method advances the testing of complex optical surfaces, potentially reducing costs and improving efficiency.