Volume 11, Number 2 • Summer 2003 • Moving Forward

Technology Opportunity Showcase highlights some unique technologies that NASA has developed and which we believe have strong potential for commercial application. While the descriptions provided here are brief, they should provide enough information to communicate the potential applications of the technology. For more detailed information, contact the person listed. Please mention that you read about it in Innovation.

Super Mirrors at Low Cost

NASA Goddard Space Flight Center is seeking companies to explore licensing a revolutionary process for precision optical polishing of bare aluminum.

The benefits of this process include low weight; thermal stability—
bimetal thermal characteristics of nickel over aluminum are poor, and pure aluminum mirrors offer excellent thermal stability; low cost—plating aluminum surfaces with electroless nickel significantly adds to the cost of the optic; smooth surface—the process yields a 5-angstrom flat and spherical mirrors and 10-angstrom aspherical mirrors, which are ideal for high-quality mirrors; and consistent quality—plating electroless nickel onto aluminum can result in faults that preclude using the optic, whereas this process consistently yields a high-quality surface and form.

Manufacturers of optics, metal optics and diamond turning and polishing equipment could license and incorporate this method into their products. The high-quality optics achieved using this method can be used in a variety of applications, including x-ray telescopes, cryogenic instruments, interferometry and medical-imaging devices.

This method begins by using a single-point diamond turning machine. Grinding cannot be used on bare aluminum—it leaves behind particles that scratch the surface during polishing. Diamond turning alone typically produces a 30- to 80-angstrom finish on standard aluminum materials. Therefore, additional polishing is required to achieve the needed smoothness for low-scatter, high-quality bare aluminum optics.

The process uses a special compound to polish the mirror to a super smooth finish. This compound not only offers superb lubricating qualities, but it also contains suspended particles. These particles are extremely hard and small, making the compound ideal for mirror polishing.

Flat and spherical mirrors polished using this process have a roughness of 5 angstroms rms, while maintaining a surface-figure accuracy of 0.125 of a wave peak to valley. Aspherical mirrors can be polished to a 10-angstrom rms finish.

The major benefit of this innovative process is the ability to make pure aluminum mirrors. Aluminum optics are less expensive and lighter than optics made from other pure materials. Q

For more information, contact Joe Famiglietti, Goddard Space Flight Center, Office of Technology Transfer, 301/286-2642, e-mail Famiglietti@nasa.gov. Please mention you read about it in Innovation.