Process Chain for Ultra-Precision and High-Efficiency Manufacturing of Large-Aperture Silicon Carbide Aspheric...

Area of Science:

• Materials Science
• Optical Engineering
• Manufacturing Technology

Background:

• Large-aperture silicon carbide (SiC) aspheric mirrors are crucial for space optical systems due to their lightweight and high stiffness.
• Processing challenges arise from SiC's hardness and multi-component nature, hindering efficient, high-precision, low-defect fabrication.

Purpose of the Study:

• To develop a novel, efficient, and high-precision process chain for manufacturing large-aperture SiC aspheric mirrors.
• To address the difficulties in processing hard and multi-component SiC materials for optical applications.

Main Methods:

• A novel process chain combining ultra-precision grinding (UPG), rapid polishing with central fluid supply, and magnetorheological finishing (MRF).
• Key technologies include wheel passivation and life prediction in UPG, pit defect control, deterministic MRF polishing, and computer-generated hologram (CGH) based detection.
• Experimental verification on a Ø460 mm SiC aspheric mirror.

Main Results:

• Achieved a final surface error of 7.42 nm RMS and a roughness (Rq) of 0.33 nm.
• Reduced initial surface error from 4.15 μm PV and 44.56 nm Rq.
• Completed the entire processing cycle in approximately 216 hours.

Conclusions:

• The proposed process chain enables efficient, high-precision, and low-defect manufacturing of large-aperture SiC aspheric mirrors.
• This advancement facilitates the mass production of critical components for advanced space optical systems.