Using curved hologram to test large-aperture convex surface.

Area of Science:

• Optical Engineering
• Metrology
• Holography

Background:

• Accurate measurement of large-aperture convex surfaces is crucial in optical manufacturing.
• Existing methods for testing aspheric surfaces can be costly and lack precision.

Purpose of the Study:

• To demonstrate an experimental optical system for measuring large-aperture convex surfaces.
• To introduce a novel computer-generated hologram (CGH) fabrication technology for improved metrology.

Main Methods:

• Fabrication of a CGH using a new technology combining laser direct writing and lithography.
• Integration of the CGH onto a concave lens surface to create an optical testing system.
• Experimental measurement of a 110 mm-diameter convex surface.

Main Results:

• The developed system successfully measured a 110 mm-diameter convex surface.
• The measurement achieved an error of 300.6 nm P-V after compensating for alignment errors.
• The new CGH technology demonstrated precise alignment, superior linear profile, and high grating resolution.

Conclusions:

• The novel optical system with the advanced CGH is effective for measuring large-aperture convex surfaces.
• This technology offers potential for higher accuracy, efficiency, and lower cost in aspheric testing.
• The system is suitable for measuring even larger convex surfaces.