SBIR-STTR Award

It is proposed to advance manufacturing science and technology to improve yield and optical surface figure in high actuator count, high-resolution deformable mirrors (DM) required for wavefront control in space-based high contrast imaging instruments. As the scale of batch fabricated, polysilicon surface micromachined MEMS DMs increases to thousands of actuators the associated increase in devices size limits the achievable yield due to micro-scale defects introduced during the manufacturing processes and large unpowered surface figure errors. In Phase I research, major obstacles preventing scalability of microfabrication processes to large arrays will be overcome by developing a polysilicon deposition process to reduce and control defect density to maximize the yield of a 1027 segment Tip-Tilt Piston DM with 3081 actuators and to determine the practical limits of the tool set and compatibility of this process for the manufacture of MEMS DMs with >104 actuators. Manufacturing processes to minimize unpowered surface figure errors will be developed to (1) reduce substrate curvature induced DM surface figure errors through control of deposition and polishing processes to balance the front and backside film thickness, and (2) reduce polishing induced DM surface figure errors by modifying the device wire routing layout design to maintain uniform pattern density across the device area to achieve uniform material removal rates in the polishing process. Successful completion of the Phase 1 work will enable the design and manufacture of a 1027 Tip-Tilt-Piston deformable mirror required for NASA's visible nulling coronagraph instrument in a Phase 2 effort.

Potential NASA Commercial Applications:
(Limit 1500 characters, approximately 150 words) The primary application for small stroke, high precision deformable mirrors is that of space-based imaging and in specific, exo-planet research. As telescopes and coronagraphs are constructed, they will require control of light using adaptive optics over a larger aperture. By expanding the size of DM devices, instruments such as PECO, ACCESS, EPIC, DaVinci, and FKSI will be able to shape more light using less hardware and less stages. Given the current constraints on fabrication technology, it is necessary to develop new methods of manufacture to accommodate for larger arrays which also require more channels for control. The desire for this type of enhanced technology within the astronomy community has been detailed in a report issued from the Association of Universities for Research in Astronomy, an influential consortium which is a voice in the United States of the industry at-large.

Potential NON-NASA Commercial Applications:
(Limit 1500 characters, approximately 150 words) There are a range of Government agencies and commercial markets that can take advantage of small stroke, high precision deformable mirrors. One application is for large, ground-based telescopes. By expanding the size of DM devices, these observatories will be able to shape more light using less hardware and less stages. Another application is long-range optical communications (lasercomm) systems for use in satellites, airborne vehicles and ground-based nodes requiring a secure, dependable connection. By creating larger, higher-precision arrays, not only is it possible to send more data at faster rates, but the distance between communication points can be extended due to enhanced error correction capabilities. A third application is for correction of quasi-static aberrations in primary optics in surveillance satellites due to manufacturing and thermal variations. Adding to its advantages of high-resolution capability, the light weight nature of BMC MEMS DM technology allows the payload to be reduced, a high priority of military satellite projects. A final application is that of laser pulse-shaping for material characterization and laser marking and machining. By creating larger arrays, control of the pulsed beams can be enhanced. In addition, the larger arrays will allow users to take advantage of larger beam diameters. This will allow scientists to better understand the composition of materials and allow manufacturers to make larger, more complex patterns. NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.

Technology Taxonomy Mapping:
Laser Optical

We propose to design and fabricate a MEMS micromirror array consisting of 1021 ultra-flat, close-packed hexagonal mirror elements, each capable of 6mrad of tip and tilt, and 1.7um of piston (TTP) motion with sub-nanometer precision as required for a space-based telescope using a hyper-contrast coronagraph for terrestrial planet finding. Fabrication process enhancements developed in the Phase I effort to increase device yield by significantly reducing the defect density in polysilicon films and reduce wafer bow by modifying thin film deposition processes, will be integrated in to the DM fabrication process to produce a device with 100% actuator yield and an unpowered peak-to-valley surface figure error of <500nm - well within the dynamic range of the DM actuators. This large array of mirror segments with tip-tilt-piston degrees of freedom and ?/100 optical quality would constitute a significant technological advance and would become an enabling component for the high contrast visible nulling coronagraph instruments planned for exoplanet imaging missions.

Potential NASA Commercial Applications:
(Limit 1500 characters, approximately 150 words) The primary application for small stroke, high precision deformable mirrors is that of space-based imaging and in specific, exo-planet research. As telescopes and coronagraphs are constructed, they will require control of light using adaptive optics over a larger aperture. By expanding the size of DM devices, instruments such as PECO, ACCESS, EPIC, DaVinci, and FKSI will be able to shape more light using less hardware and less stages. Given the current constraints on fabrication technology, it is necessary to develop new methods of manufacture to accommodate for larger arrays which also require more channels for control. The desire for this type of enhanced technology within the astronomy community has been detailed in a report issued from the Association of Universities for Research in Astronomy, an influential consortium which is a voice in the United States of the industry at-large.



Potential NON-NASA Commercial Applications:
:
(Limit 1500 characters, approximately 150 words) There are a range of Government agencies and commercial markets that can take advantage of small stroke, high precision deformable mirrors. One application is for large, ground-based telescopes. By expanding the size of DM devices, these observatories will be able to shape more light using less hardware and less stages. Another application is long-range optical communications (lasercomm) systems for use in satellites, airborne vehicles and ground-based nodes requiring a secure, dependable connection. By creating larger, higher-precision arrays, not only is it possible to send more data at faster rates, but the distance between communication points can be extended due to enhanced error correction capabilities. A third application is for correction of quasi-static aberrations in primary optics in surveillance satellites due to manufacturing and thermal variations. Adding to its advantages of high-resolution capability, the light weight nature of BMC MEMS DM technology allows the payload to be reduced, a high priority of military satellite projects. A final application is that of laser pulse-shaping for material characterization and laser marking and machining. By creating larger arrays, control of the pulsed beams can be enhanced. In addition, the larger arrays will allow users to take advantage of larger beam diameters. This will allow scientists to better understand the composition of materials and allow manufacturers to make larger, more complex patterns.

Technology Taxonomy Mapping:
(NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.) Laser Optical Optical & Photonic Materials