Small Business Innovation Research/Small Business Tech Transfer
Optical Fabrication and Metrology of Aspheric and Freeform Mirrors
Project Description
The requirement for cost effective manufacturing and metrology of large optical surfaces is instrumental for the success of future NASA programs such as LISA, WFIRST and IXO. OptiPro's UltraForm Finishing (UFF) is a sub-aperture compliant wheel and belt type polishing process for rapid material removal from the ground state to a finished optic. The UFF removes residual grinding sub-surface damage, mid spatial frequency errors, and provides the mechanism required for surface corrections. OptiPro's technologically advanced optical manufacturing capabilities along with a support partnership with the University of Rochester Mechanical Engineering Department and the Penn State EOC, gives us a very strong team and a clear path towards solving the difficult problems associated with, grinding, polishing and metrology of large complex optical surfaces. The UFF, with its 5 axis of motion provides a platform to polish traditional flats and spheres as well as aspheres and freeform shapes. The UFF was designed for deep concave shapes and it is suitable for finishing conformal optics. The proposed Phase I will include testing the feasibility of implementing large UFF tools for grinding and polishing of a scaled down fused quartz cylinder (200 x 200 mm) which represents the large forming mandrel material and geometry. Grinding as well as polishing forces will be optimized by using finite element analysis (FEA) techniques. The part geometry will be measured by a non contact optical probe using OptiPro's UltraSurf free-form measurement system. We envision that the work done during Phase I will be extended during Phase II to a large tapered cylinder forming mandrel or an aspheric mirror surface with integration of the UltraSurf capabilities to the UFF platform. Currently the UFF and UltraSurf platforms address the fabrication requirements for small aspheric and freeform optics, this proposal implements new tools on these platforms required for the fabrication of large mirrors.
More »
Anticipated Benefits
UltraForm Finishing (UFF) is a CNC controlled process designed to remove grinding sub surface damage as well as mid spatial frequency errors for both relatively "soft" glasses as well as "hard" metals and ceramics for many applications. These applications may include the fabrication of forming mandrels used to produce multiple segmented shell mirrors for the International X-Ray Observatory (IXO). The aspheric and freeform optical surfaces required by LISA and WFIRST will benefit from the fabrication advances made with this endeavor. By integrating finite element analysis (FEA) tools with the UFF computer aided manufacturing (CAM) interface, we will be able to optimize the fabrication process and subsequently reduce and/or completely eliminate mid spatial frequency errors. The UFF has the capability to work with a wide range of traditional optical mediums (i.e., combination of belt materials and loose abrasives) in addition to wheels that range from approximately 20 mm up to 150 mm. This makes the UFF suitable for polishing a wide variety of materials for other segmented types of telescope systems such as the Advanced Technology Large Aperture Space Telescope (ATLAST). The wide variety of loose and bound abrasives allows the UltraForm platform to finish hard ceramics, Silicon and SiC. With these hard to process materials, the UFF has shown promise for grinding as well as polishing optical surfaces, on a small scale.
Since 1989 OptiPro has developed and refined conceptual technologies into robust deterministic machines and processes for the optical fabrication industry. Non-NASA commercial applications include the fabrication of flats, spheres, aspheres, and complex conformal shapes such as aerodynamic ogive domes. Commercialization of these technologies has driven very cost effective solutions. The UFF polishing tools' ability to polish a variety of materials from the ground state, removing grinding marks and subsurface damage, makes it especially attractive for applications where mid-spatial-frequency surface errors are an issue such as EUV lithography. Another application is for laser amplifiers, such as the Inertial Confinement Fusion National Ignition Facility (NIF) at Lawrence Livermore National Laboratory and the Laboratory for Laser Energetics, at the University of Rochester. For these types of applications, laser damage threshold and irradiance distribution are critical and therefore mid-spatial frequency errors need to be minimized after the polishing stage. More »
Since 1989 OptiPro has developed and refined conceptual technologies into robust deterministic machines and processes for the optical fabrication industry. Non-NASA commercial applications include the fabrication of flats, spheres, aspheres, and complex conformal shapes such as aerodynamic ogive domes. Commercialization of these technologies has driven very cost effective solutions. The UFF polishing tools' ability to polish a variety of materials from the ground state, removing grinding marks and subsurface damage, makes it especially attractive for applications where mid-spatial-frequency surface errors are an issue such as EUV lithography. Another application is for laser amplifiers, such as the Inertial Confinement Fusion National Ignition Facility (NIF) at Lawrence Livermore National Laboratory and the Laboratory for Laser Energetics, at the University of Rochester. For these types of applications, laser damage threshold and irradiance distribution are critical and therefore mid-spatial frequency errors need to be minimized after the polishing stage. More »
Primary U.S. Work Locations and Key Partners
| Organizations Performing Work | Role | Type | Location |
|---|---|---|---|
| OptiPro Systems, LLC | Lead Organization | Industry | Ontario, New York |
Marshall Space Flight Center
(MSFC)
|
Supporting Organization | NASA Center | Huntsville, Alabama |
Primary U.S. Work Locations
-
Alabama
-
New York
Suggest an Edit
Recommend changes and additions to this project record.
This is a historic project that was completed before the creation of TechPort on October 1, 2012. Available data has been included. This record may contain less data than currently active projects.