FAQs

FAQs


What is the maximum lens diameter the MRF® system is capable of polishing?

QED's current line of commercial MRF polishing systems can polish optics that range in size from just a few millimeters up to optics that exceed 1 meter.

The Q22-XE can polish optics up to 100 mm. The Q22-X and Q22-Y have a nominal maximum diameter capacity of 200 mm, with a maximum weight capacity of 7kg (workpiece and holder). For certain lens geometries, the maximum diameter can be greater than 200 mm. The Q22-400X has a nominal maximum lens diameter of 400 mm. The Q22-750P2 extends MRF finishing to large plano optics up to 750 mm x 1000 mm.  QED's latest machine, the Q22-950F brings finishing capabilities to optics up to 950 mm x 1250 mm, including off-axis aspheres and freeform optics.


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What limitation does the MRF® process have for polishing different materials?


The Q22 MRF systems have been used successfully to polish many different materials, including most optical glasses and single crystals such as calcium fluoride.

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Can MRF® be used for polishing concave surfaces?


Yes. The standard machine can polish over a range from a convex hemisphere to plano, to a concave radius of curvature of 90 mm. Our small wheel package allows polishing of concave radius of curvature as small as 15 mm.

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What limitation does the MRF® process have for polishing aspheres?

MRF does not have any inherent limitations for polishing of aspheres. The process may be used to polish (figure correct and smooth) aspheres with mild-departure (<20 microns) or  with large-departure (hundreds of microns). Additionally, MRF is very adept at "aspherizing," i.e., polishing in the aspheric shape from a best-fit-sphere, particularly for mild aspheres.

The primary concerns are the availability of metrology and preparation prior to MRF, each of which can be more difficult as aspheric departure increases.


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Can MRF® be used for polishing prisms?

Yes. The Q22-Y raster polishing system may be used to perform figure or angle correction on prisms, as well as any rectangular aperture smaller than 200 x 200 mm.


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What is the best surface figure that can be produced on the MRF® machine?

We have not yet found an absolute limit to MRF. The highest possible accuracy that may be accomplished is driven by the initial part accuracy and the part metrology. We have routinely achieved surface figures of less than 10 nm p-v.


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What is the typical surface finish (rms microroughness) that can be achieved with MRF®?


As with surface figure, MRF's ability to achieve low surface roughness is driven by the initial condition, as well as the material being polished and the metrology that is used. On optical glasses, MRF routinely achieves microroughness of less than 10 angstroms rms

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Why is MRF® better than conventional polishing?

MRF is a deterministic polishing technique. It is deterministic because the polishing tool effectively doesn't change, and the removal function is interferometrically characterized. Because the removal is highly stable, and can be characterized interferometrically, the system can efficiently deliver high precision parts. Other advantages are that the polishing tool is easily adjusted, and conforms perfectly to the workpiece surface, enabling aspheric polishing. The process achieves very high removal rates with no normal loads, and therefore no subsurface damage.

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Is the MRF® process patented?


Yes, there are fundamental method, apparatus, and fluid patents protecting MRF.

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Can I get a demonstration of the MRF® process on my production parts?


QED has a fully equipped applications laboratory and welcomes the opportunity to provide prospective customers with a complete demonstration on production parts—just call, fax, or This e-mail address is being protected from spambots. You need JavaScript enabled to view it. your request.

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