Novel high-NA MRF toolpath supports production of concave hemispheres

Chris Maloney; Chris Supranowitz; Paul Dumas

doi:10.1117/12.2279818

16 October 2017 Novel high-NA MRF toolpath supports production of concave hemispheres

Chris Maloney, Chris Supranowitz, Paul Dumas

Proceedings Volume 10448, Optifab 2017; 1044806 (2017) https://doi.org/10.1117/12.2279818
Event: SPIE Optifab, 2017, Rochester, New York, United States

Abstract

Many optical system designs rely on high numerical aperture (NA) optics, including lithography and defense systems. Lithography systems require high-NA optics to image the fine patterns from a photomask, and many defense systems require the use of domes. The methods for manufacturing such optics with large half angles have often been treated as proprietary by most manufacturers due to the challenges involved. In the past, many high-NA concave surfaces could not be polished by magnetorheological finishing (MRF) due to collisions with the hardware underneath the polishing head. By leveraging concepts that were developed to enable freeform raster MRF capabilities, QED Technologies has implemented a novel toolpath to facilitate a new high-NA rotational MRF mode. This concept involves the use of the B-axis (rotational axis) in combination with a “virtual-axis” that utilizes the geometry of the polishing head. Hardware collisions that previously restricted the concave half angle limit can now be avoided and the new functionality has been seamlessly integrated into the software. This new MRF mode overcomes past limitations for polishing concave surfaces to now accommodate full concave hemispheres as well as extend the capabilities for full convex hemispheres. We discuss some of the previous limitations, and demonstrate the extended capabilities using this novel toolpath. Polishing results are used to qualify the new toolpath to ensure similar results to the “standard” rotational MRF mode.

Citation Download Citation

Chris Maloney, Chris Supranowitz, and Paul Dumas "Novel high-NA MRF toolpath supports production of concave hemispheres ", Proc. SPIE 10448, Optifab 2017, 1044806 (16 October 2017); https://doi.org/10.1117/12.2279818

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