Daryl J. Dagel

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.

Stress and curvature in MEMS mirrors

The goal of this study is to understand how to optimize the performance of micro-mirrors for a variety of optical microsystem applications. Our approach relies on a number of process variations and mirror designs to ultimately produce relatively large (500μm to mm-scale), smooth (for nm RMS), and flat mirrors (greater than 1m curvature). White-light interferometric measurements, and finite element models are discussed in support of these findings. Stress gradients and residual stresses have been measured for accurate modeling of micro-mirrors. Through this modeling study, we have identified relevant structural parameters that will optimize SUMMiT V MEMS mirrors for optical applications. Ways of mitigating surface topography, print-through effects, and RMS roughness are currently being investigated.

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

Out-of-plane rotary micromirrors for reconfigurable photonic applications

A slow-speed optical fiber cross-connect has been developed around surface-micromachined MEMS mirrors that pop up 45 degrees relative to the substrate and rotate 360 degrees about the normal axis. Various assembly, latching, and rotational mechanisms have been evaluated and tested, with current work focusing on demonstrating functionality. Routing capability has been characterized for 2 × 2 arrays of micromirrors, the feedback from which has been applied to second-generation designs with improved control and greater precision. The cross-connect described here is scalable and represents an important building block in a general-purpose photonic infrastructure.

Four-color imaging pyrometer for mapping temperatures of laser-based metal processes

A 4-color imaging pyrometer was developed to investigate the thermal behavior of laser-based metal processes, specifically laser welding and laser additive manufacturing of stainless steel. The new instrument, coined a 2x pyrometer, consists of four, high-sensitivity silicon CMOS cameras configured as two independent 2-color pyrometers combined in a common hardware assembly. This coupling of pyrometers permitted low and high temperature regions to be targeted within the silicon response curve, thereby broadening the useable temperature range of the instrument. Also, by utilizing the high dynamic range features of the CMOS cameras, the response gap between the two wavelength bands can be bridged. Together these hardware and software enhancements are predicted to expand the real-time (60 fps) temperature response of the 2x pyrometer from 600 °C to 3500 °C. Initial results from a calibrated tungsten lamp confirm this increased response, thus making it attractive for measuring absolute temperatures of steel forming processes.

A comprehensive approach to decipher biological computation to achieve next generation high-performance exascale computing.

The human brain (volume=1200cm3) consumes 20W and is capable of performing>10%5E16 operations/s. Current supercomputer technology has reached 1015 operations/s, yet it requires 1500m%5E3 and 3MW, giving the brain a 10%5E12 advantage in operations/s/W/cm%5E3. Thus, to reach exascale computation, two achievements are required: 1) improved understanding of computation in biological tissue, and 2) a paradigm shift towards neuromorphic computing where hardware circuits mimic properties of neural tissue. To address 1), we will interrogate corticostriatal networks in mouse brain tissue slices, specifically with regard to their frequency filtering capabilities as a function of input stimulus. To address 2), we will instantiate biological computing characteristics such as multi-bit storage into hardware devices with future computational and memory applications. Resistive memory devices will be modeled, designed, and fabricated in the MESA facility in consultation with our internal and external collaborators.

Integrated FET-Polysilicon Micromachining Process for Optical MEMS

Co-fabricated transistors in the SUMMiTtrade process enable large scale micromirror arrays with practical pin-out. Novel drive circuitry and optical/electrical performance for initial micromirror arrays are described

MEMS Adaptive Optics Devices: LDRD No. 02-1385 Summary Report

The primary goal of this portion of the LDRD is to develop a vertical programmable diffraction grating that can be fabricated with Sandias Ultra-planar Multi-level MEMS Technology, the SUMMiT V{trademark} process. This grating is targeted for use in a chemical detection system dubbed the Polychromator. A secondary goal is to design diffraction grating structures with additional degrees of freedom (DOF). Gratings with 2.5 microns of vertical stroke have been realized. In addition, rotational DOF grating structures have been successfully actuated, and a structure has been developed that minimizes residual stress effects.

Optomechanical spring effect readout in resonant micro-optical Sagnac gyroscopes design and scaling analysis

We propose and theoretically analyze a new cavity optomechanical oscillator gyroscope. Mechanical frequency acts as a sensitive readout of rotation through the optomechanical spring and Sagnac effects. Remarkably, reducing device size improves scale factor.

Measurement of Laser Weld Temperatures for 3D Model Input

Laser welding is a key joining process used extensively in the manufacture and assembly of critical components for several weapons systems. Sandia National Laboratories advances the understanding of the laser welding process through coupled experimentation and modeling. This report summarizes the experimental portion of the research program, which focused on measuring temperatures and thermal history of laser welds on steel plates. To increase confidence in measurement accuracy, researchers utilized multiple complementary techniques to acquire temperatures during laser welding. This data serves as input to and validation of 3D laser welding models aimed at predicting microstructure and the formation of defects and their impact on weld-joint reliability, a crucial step in rapid prototyping of weapons components.