Interferometric testing of high-numerical-aperture convex surfaces

Area of Science:

• Optical engineering
• Metrology
• Lens system testing

Background:

• Interferometric testing of convex surfaces in high numerical aperture (N.A.) lens systems poses significant challenges.
• Existing methods may require complex setups or specialized reference optics.

Purpose of the Study:

• To present a novel interferometric method for testing convex surfaces.
• To overcome the difficulties associated with testing large N.A. optics.

Main Methods:

• Utilizing the aplanatic imaging properties of a spherical surface.
• Employing a reference surface with a significantly smaller N.A. compared to the test optic.

Main Results:

• Successful demonstration of testing large N.A. convex surfaces using a low-N.A. reference.
• The method simplifies the interferometric testing process.

Conclusions:

• The proposed technique offers a practical solution for testing challenging convex surfaces.
• Leveraging aplanatic imaging provides an effective way to reduce N.A. mismatch in interferometry.