Combining SSI & MRF to Reach
λ/75 PV on a Plano
High precision optical flat surfaces are used in a number of applications, including reference surfaces, stage mirrors, and laser cavities. Manufacturing a plano surface to λ/75 peak-to-valley (PV) can be challenging for many reasons.
- Conventional polishing methods usually are not deterministic enough to reach this level of precision for various part sizes and aperture shapes with predictable throughput.
- Magnetorheological Finishing (MRF™) is a computer-controlled subaperture polishing process, that is deterministic. However, computer controlled processes like MRF need sufficiently-accurate, full-aperture metrology to “drive” the process, i.e. to tell the software where the highs & lows of the surface error are.
- Metrology needs to be accurate enough in two (2) key quality areas:
- Vertical resolution/accuracy – the ability for the instrument to resolve and accurately quantify the amplitude of the highs & lows of the surface error
- Lateral resolution/accuracy – the ability of the instrument to accurately represent the position of the highs & lows of the surface error
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