Off-spindle-axis spiral grinding of aspheric microlens array mold inserts.

Area of Science:

• Precision Engineering
• Optical Manufacturing
• Materials Science

Background:

• Fabricating aspheric microlens arrays (AMLA) is crucial for advanced optical systems.
• Existing methods face challenges in achieving high form accuracy and surface quality for mold inserts.

Purpose of the Study:

• To present a novel off-spindle-axis (OSA) spiral grinding method for AMLA mold inserts.
• To investigate the determination of wheel path and form error compensation using on-machine measurement.
• To evaluate the performance of OSA spiral grinding in fabricating high-accuracy mold inserts for precision glass molding (PGM).

Main Methods:

• Developed an OSA spiral grinding process synchronizing three translational motions with workpiece rotation.
• Implemented on-machine measurement for real-time form error compensation.
• Fabricated a tungsten carbide mold insert with four convex aspheric lens-lets.
• Conducted PGM experiments using the fabricated mold insert.

Main Results:

• Achieved homogeneous quality for both ground mold inserts and molded AMLA.
• Demonstrated form accuracy of less than 0.3 µm (PV) for both mold inserts and molded AMLA.
• Attained a surface roughness of 10 nm (Sa) for both mold inserts and molded AMLA.

Conclusions:

• The OSA spiral grinding method is effective for fabricating high-accuracy AMLA mold inserts.
• The developed method enables sub-micrometer form accuracy compensation via on-machine measurement.
• The process is suitable for producing high-quality glass AMLA through precision glass molding.