An investigation study concerning positioning, alignment, bonding and packaging of optical fibers for interfacing with
optical MEMS devices is being reviewed in this paper. The study includes a review of techniques and critical issues for
optical fiber positioning, alignment, bonding, optical improvements, and coupling and interfacing through micro-lenses
and waveguides. Also, we present a packaging design structure for hermetic sealing of optical MEMS devices requiring
interfacing through optical fibers which considers aspects such as processes, assemble schemes and bonding techniques
for Optical Fibers, which are briefly reviewed in this work. This packaging design considers the following conditions:
hermeticity of the MEMS devices, optical fiber and MEMS die alignment and positioning, assembly process, and Simachined
fixturing design for final assembly and positioning.
Micro Nano Technology-Based Systems (MNT-Based Systems) are expected to provide unprecedented capabilities for aerospace applications. However we have not sufficiently addressed the reliability of such systems for a number of reasons. For example, our foundational understanding of such systems is incomplete at the basic physics level and our understanding of how individual subsystems interact is much less than we originally assumed. In addition the manner in which we operate during the product realization cycle has large implications for the ultimate reliability we can expect to achieve. Currently it is quite difficult to determine the reliability of MNT-Based Systems and is in fact borne out by a number of estimates we have seen that are unsatisfactory. We shall discuss a number of issues that at present have slowed our progress in developing NMT-Based Systems and have deterred us from effectively ascertaining the true "reliability" of such systems.
This report presents modeling and simulation work for analyzing three designs of Micro Electro Mechanical Systems (MEMS) Compound Pivot Mirrors (CPM). These mirrors were made using the polysilicon SUMMiT<sup>TM</sup> process. At 75 volts and above, initial experimental analysis of fabricated mirrors showed tilt angles of up to 75 degrees for one design, and 5 degrees for the other two. Nevertheless, geometric design models predicted higher tilt angles. Therefore, a detailed finite element modeling study was conducted to explain why lower tilt angles occurred and if design modifications could bemade to produce higher tilt angles at lower voltages. This study showed that the spring stiffness of the mirrors was too great to allow for desired levels of rotation at lower levels of voltage. To create lower spring stiffness, a redesign is needed.
This paper describes a potential application of silicon surface micromachined (SMM) mirrors to a space imaging application. We have developed micromirror arrays that can be individually addressed for potential use in a spectrometer planned for NASA's Next Generation Space Telescope (NGST), which will be launched later this decade. An array of micromirrors has been designed to replace a conventional fixed slit mask that is commonly used in spectrometer instruments. The fixed slit mask is used to select the desired portions of an incoming optical signal for analysis. These mirrors are designed to operate in two states, on and off, with the on position directing the signal into the instrument. Such an array of micromirrors can then be used as a "programmable" slit mask where portions of the incoming field of view can be selected in software.
In this paper we describe optical and dynamic performance of tip/tilt micromachined mirrors fabricated using the SUMMIT V surface micromachining process. We find that the tilt angle for a given mirror design is determined by a combination of geometric factors and stiffness of the capacitive suspension. Switching speeds of ~40-50 microsecond(s) econds are measured for 50 micrometers -square mirrors. Finally surface roughness and curvature before and after metallization are obtained using white light interferometry.
This paper describes mechanical designed concepts for a class of pivoting micromirrors that permit relatively large angles of orientation to be obtained when configured in large arrays. Micromirror arrays can be utilized in a variety of applications ranging from optical switching to beam-front correction in a variety of technologies. This particular work is concerned with silicon surface micromachining. The multi-layer polysilicon surface micromachined process developed at Sandia National Laboratories is used to fabricate micromirror arrays that consists of capacitive electrode pairs which are used to electrostatically actuator mirrors to their desired positions and suitable elastic suspensions which support the 2 micrometers thick mirror structures. The designs described have been fabricated and successfully operated.
This paper discusses the design, fabrication and testing of a surface micromachined Counter-Meshing Gears discrimination device which functions as a mechanically coded lock. A 24 bit code is input to unlock the device. Once unlocked, the device provides a path for an energy or information signal to pass through the device. The device is designed to immediately lock up if any portion of the 24 bit code is incorrect. The motivation for the development of this device is based on occurrences referred to as High Consequence Events. A High Consequence Even is an event where an inadvertent operation of a system could result in the catastrophic loss of life, property, or damage to the environment.
Understanding the parameters that affect the performance of milliscale and microscale actuators is essential to the development of optimized designs and fabrication processes, as well as the qualification of devices for commercial applications. This paper discusses the development of optical techniques for motion measurements of LIGA fabricated milliengines. LIGA processing permits the fabrication of precision millimeter-sized machine elements that cannot be fabricated by conventional miniature machining techniques because of their small feature sizes. In addition, tolerances of 1 part in 10<SUP>3</SUP> to 10<SUP>4</SUP> may be maintained in millimeter sized components with this processing technique. Optical techniques offer a convenient means for measuring long term statistical performance data and transient responses needed to optimize designs and manufacturing techniques. Optical techniques can also be used to provide feedback signals needed for control and sensing of the state of the machine. Optical probe concepts and experimental data obtained using a milliengine developed at Sandia National Laboratories are presented.
Several authors have given overviews of microelectromechanical systems, including microactuators. In our presentation we review some of these results, and provide a brief description of the basic principles of operation, fabrication, and application, of a few selected microactuators (electrostatic and surface tension driven). We present a description of a three- level mechanical polysilicon surface-micromachining technology with a discussion of the advantages of this level of process complexity. This technology is capable of forming complex, batch-fabricated, interconnected, and interactive, microactuated micromechanisms which include optical elements. The inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. Two examples of microactuators fabricated using this process are provided to illustrate the capabilities and usefulness of the technology. The first actuator is an example of a novel actuation mechanism based on the effect of surface tension at these micro-scale dimensions and of a microstructure within a microstructure. The second is a comb-drive-based microengine which has direct application as a drive and power source for micro optical elements, specifically, micro mirrors and micro shutters. This design converts linear oscillatory motion from electrostatic comb drive actuators into rotational motion via a direct linkage connection. The microengine provides output in the form of a continuously rotating output gear that is capable of delivering drive torque to a micromechanism.