Bernhard Jokiel

Large-stroke MEMS deformable mirrors for adaptive optics

Surface-micromachined deformable mirrors that exhibit greater than 10 /spl mu/m of stroke are presented. The segmented arrays described here consist of 61 and 85 hexagonal, piston/tip/tilt mirrors (three actuators each) with diameters of 500 and 430 /spl mu/m, respectively, and fill a 4 mm circular aperture. Devices were packaged in 208 and 256 pin-grid arrays and driven by a compact control board designed for turn-key operation. After metallization and packaging mirror bow is /spl sim/680 nm (/spl lambda//1), but a heat-treatment procedure is proposed for controlling mirror curvature to better than /spl lambda//10. An optical test bed was used to demonstrate basic beam splitting and open-loop aberration correction, the results of which are also presented.

Uncertainty propagation in calibration of parallel kinematic machines

Abstract This paper outlines in detail a method for determining the uncertainty present in the kinematic parameters (joint locations, initial strut lengths, and spindle location and orientation) for parallel kinematic devices after calibration. The uncertainty estimation method using Monte Carlo simulations was applied to a sequential method for determining the kinematic parameters of fully assembled Hexel Tornado 2000 (a 6–3 Stewart platform) milling machine. Results for the uncertainty present in the kinematic parameters of a Hexel Tornado 2000 milling machine after calibration using a SMX 4,000 laser tracker are shown.

MEMS Mirror Arrays for Adaptive Optics Applications

A high fill-factor 61-element array containing 0.5 mm hexagonal mirrors that tip, tilt and piston with a 27 mum stroke has been fabricated in SUMMiT Vtrade technology. Design, fabrication and performance will be discussed

Failure analysis of a multi-degree-of-freedom spatial microstage

Spatial microstages are microfabricated controlled platforms that can be popped out of the fabrication plane and are free to move in three-dimensional (3D) space. Spatial microstages have shown promise for use in MOEMS for adaptive optics, automatic focusing systems, fiber optic alignment/precision positioning, real time optical alignment, interconnects, and a host of other applications. These devices were designed and fabricated to position a controllable stage in 3D space from microassembly and microfabrication. Microstages can be designed and fabricated to move in plane (x, y) and out of plane (z). Advanced microstages are designed to move in plane, out-of-plane, rotate, and tilt about x, y, and z. Design and fabrication of the rotational and tilt components are critical in performing the three-dimensional pop up and tilting action needed for precise micropositioning. The device used for analysis contains linear racks driven by electrostatic actuators. The actuators are attached to a microstage through a hinge component with revolving, rotating, and tilting joints. The actuators allow x, y, and z positioning while the hinge allows rotational motion along the stage. Failure analysis of the Sandia fabricated microstage was performed on released and as fabricated microstages. Failure analysis of these devices revealed design and fabrication irregularities along the revolving components of the hinge. This paper will discuss the design and functionality of the microstage, failure analysis activities and failure mechanisms found in polysilicon fabricated microstages, corrective actions and design improvements.

Quantum Simulations in Ion Traps

We are using an array of laser-controlled strontium ions confined in a linear rf trap to build a multi-body quantum simulator to solve otherwise intractable many-body quantum problems.