Blake Lin
Department of Electrical Engineering and Computer Sciences, UC Berkeley
BSAC Graduate Student Researcher Dissertation Presentation
May 14, 2008 | 12:00 to 01:00 | 521 Cory Hall, Hogan Room
Host: Tsu-Jae King Liu & Richard Muller
Image resolutions of modern optical systems are many times limited by wavefront aberrations due to turbulence in the optical media. Adaptive Optics (AO) is a technology that utilizes a deformable mirror (DM) to correct the wavefront distortion, thereby enhancing the image resolution. In this thesis research, we investigate the design and fabrication of micromechanical-deformable-mirror arrays for AO applications. Because the AO applications require large arrays (100s-1000s of segments) of closely-spaced deformable mirrors, it is desirable that the DM arrays can be integrated with CMOS control electronics. In this research, we develop a CMOS-compatible fabrication process for the DM arrays, in which polycrystalline-silicon-germanium (poly-SiGe) and polycrystalline-germanium (poly-Ge) are used as the structural and sacrificial materials, respectively. One major challenge of using poly-SiGe as the structural material is to reduce the high strain gradient in as-deposited poly-SiGe films, because the low-thermal-budget requirement for post-CMOS integration prohibits the use of a high-temperature annealing step. In this research, the use of a bilayer structure to reduce the strain gradients of poly-SiGe is investigated. The AO applications also require that the micromechanical deformable mirrors can provide large displacements (i.e. 10-20 um). In this research, we utilize the strain gradients of poly-SiGe to elevate the top plates of the parallel-plate mirror actuators, creating a large original gap for large-displacement actuations. Using the technologies developed in this research, we demonstrate a 37-segment deformable-mirror array for vision-science AO applications.
---
Interested in nominating someone to speak at the BSAC Technology Seminar? We welcome you to submit a speaker nomination here