Interferometric metrology probe for highly sloped freeform optics

Area of Science:

• Optical Engineering
• Metrology
• Surface Science

Background:

• Characterizing aspheric and freeform optical surfaces requires advanced metrology systems.
• Steep surface slopes present challenges for traditional freeform metrology, impacting accuracy and stage design.
• Accurate measurement of complex optical geometries is crucial for advanced optical system performance.

Purpose of the Study:

• To present an interferometric surface metrology probe capable of measuring highly sloped aspheric and freeform optical surfaces.
• To overcome limitations of existing systems in characterizing steep surface gradients.
• To improve the accuracy and simplify the design of metrology systems for complex optical surfaces.

Main Methods:

• Development of an interferometric probe with an optical design enabling measurement of surface slopes up to 50 degrees without probe tilting.
• Utilizing a spectrally controlled light source to generate a virtual ball for surface distance and angle measurement.
• Reconstructing the surface profile by fitting Zernike polynomials to a generated point cloud.

Main Results:

• The probe successfully measures highly sloped surfaces (up to 50 degrees) without requiring probe tilting.
• The system demonstrates simplified stage design and increased measurement accuracy.
• Sensitivity tests and accuracy results will be presented to validate the system's performance.

Conclusions:

• The developed interferometric probe offers a robust solution for metrology of steep aspheric and freeform optical surfaces.
• The probe's design enhances accuracy and simplifies metrology setups for complex optical components.
• This advancement facilitates more precise characterization of advanced optical surfaces.