Reflective spatial light modulator for high-dynamic-range wavefront control

Optical MEMS arrays have begun to transform the field of adaptive optics for astronomy, vision science, and laser communication. They are faster, more compact, less expensive, and more power efficient than alternative technologies. The principal technicalobjective of this Phase I project will be to build and demonstrate a 150 x 150 element micromachined spatial light modulator (¿SLM) that can achieve high dynamic range, unprecedented frame rates, and precise wavefront-fitting. The device will be integrateddirectly on a CMOS driver chip, and will be controllable digitally through a personal computer. Fabricated using metal micromachining processes developed at Boston Micromachines Corporation, the ¿SLM will allow up to 1¿m physical throw (2¿m optical pathdifference) for each of the 22,500 mirror pixels at 4 kHz frame rate. Challenges associated with design, process development, fabrication and testing will be addressed in Phase I research. In Phase II, megapixel devices (~200 mm diameter) will be producedusing the same device architecture. If successful, the Phase I research project will yield a high-speed, reflective spatial light modulator with 22,500 independent pixels, 4-bit phase resolution, and 4 kHz frame rate. It will be usable over a range ofwavelengths from 400 nm to 2 ¿m. If controlled using modulo-lambda phase wrapping, this device will be capable of correcting tens of waves of optical path difference across its 15 mm aperture. The device architecture will be fully scalable, takingadvantage of sequentially processed, vertically integrated arrays of CMOS electronics, MEMS electromechanical actuators, and optical-quality MEMS micromirrors. This architecture will enable a generation of new devices for phase and amplitude modulation.Moreover, the fabrication technology developed ? low temperature metal MEMS surface micromachining to optical tolerances ? will provide a foundation upon which other active optical components could be developed. Boston Micromachines Corporation hascommercialized the world?s highest quality deformable mirror devices, and has established strategic partnerships with several leading developers of adaptive optics technology in the application areas of vision science, astronomy, and laser communication.The ¿SLM takes advantage of key drivers for successful MEMS commerce, leveraging our existing products with a timely and important complementary product in the field of optical wavefront control.