In this paper we present a MOEMS based miniaturized Fourier-transform infrared (FTIR) spectrometer capable to perform time resolved measurements from NIR to MIR. The FTIR-spectrometer is based on a MOEMS translatory actuator which replaces the macroscopic mirror drive enabling a miniaturized, robust and low cost FTIR system. The MOEMS device is manufactured in a CMOS compatible process using SOI technology. Due to the electrostatic driving principle based on in-plane electrode combs, 200 μm stroke can be achieved with comparatively low voltages (<40 V) at an ambient pressure below 500 Pa. The actuator plate, acting as mirror with an area of 1.65 mm², operates at a resonant frequency of 5 kHz. Consequently this yields a maximum spectral resolution of 25 cm^-1 and an acquisition time of 200 μs per spectrum. Based on a Michelson setup the infrared optical bench of the presented FTIR system is designed to account for the mirror aperture and the desired spectral bandwidth of 2 μm to 5 μm. The integrated signal processing electronics has to cope with a bandwidth of 8 MHz as a result of the mirror motion. A digital signal processor manages system control and data processing. The high acquisition rate and integration level of the system makes it appropriate for applications like process control and surveillance of fast reactions. First results of transmission and absorbance measurements are shown. In addition we present a novel MOEMS device with increased mirror aperture and stroke which will be used for further optimization of the spectral FTIR-resolution.

We report on micromirror arrays being developed for the use as reflective slit mask in Multi Object Spectrographs for astronomical applications. The micromirrors are etched in bulk single crystal silicon whereas the cantilever type suspension is realized by surface micromachining. One micromirror element is 100μm x 200μm in size. The micromirrors are actuated electrostatically by electrodes located on a second chip. The use of silicon on insulator (SOI) wafers for both mirror and electrode chip ensures thermal compatibility for cryogenic operation. A system of multiple landing beams has been developed, which passively locks the mirror at a well defined tilt angle when actuated. The mechanical tilt angle obtained is 20^o at a pull-in voltage of 90V. Measurements with an optical profiler showed that the tilt angle of the actuated and locked mirror is stable with a precision of one arc minute over a range of 15V. This locking system makes the tilt angle merely independent from process variations across the wafer and thus provides uniform tilt angle over the whole array. The precision on tilt angle from mirror to mirror measured is one arc minute. The surface quality of the mirrors in actuated state is better than 10nm peak-to-valley and the local roughness is around 1nm RMS.

A Micro-Electro-Mechanical-System (MEMS) based handheld material analyzer has been developed and demonstrated to efficiently identify plastic materials for the recycling industry.

Spectroscopy in the infrared region is today an important application to measure, control and investigate liquids or gases in industrial, medical or environmental applications. We have developed a small, transportable NIRspectrometer with a size of only 120 x 80 x 80 mm³, and a MOEMS-scanning-grating chip as main element. The scanning-grating chip is resonantly driven by a pulsed voltage of only 36V, has a mirror aperture of 3 x 3 mm² and reaches maximum deflection angles of +/- 11^o. The NIR-micro-spectrometer works currently in a spectral range of 1200 - 1900 nm with a resolution of less than 10 nm using only one single InGaAs-diode as detector. Additionally, scanning grating chips have been already developed for spectral ranges of 900 - 1800 nm and 1250 - 2500 nm. One entire spectral measurement is done within 6 milliseconds, calculated by a digital signal processor, which is included in the spectrometer. Results can be either displayed by special computer software or directly by a graphical user interface. In this paper, we will focus on the control of the grating fabrication process, which can be done by microscopy, using new control structures. A time-consuming control with SEM (Scanning electron microscope) is no longer needed. Furthermore the characterization of the fabrication process and its consequence on the spectrometer properties will be discussed, as well as the characterization of the scanning grating chip itself (frequency, movement, static deformation, spectral efficiency...). Characteristic measurement results of an argon calibration lamp, which shows the performance of the NIR-micro-spectrometer, will be presented as well.

This paper reports design, fabrication and test results of a tunable pyroelectric detector with an integrated micromachined Fabry-Perot (FP) filter for gas analysis in the Mid-Wave Infrared (MWIR). The new approach is based on a bulk micromachined Fabry-Perot interferometer with an air cavity, which is electrostatically tuned. Various types of moveable reflectors and spring configurations have been fabricated to determine the optimum solution with respect to maximum tuning range, low gravity influence on center wavelength and suitable filter bandwidth. Short and long cavity filters were designed for the spectral ranges of 3...4.3 μm and 3.7...5.0 μm respectively. The tunable filter is arranged on top of a current mode pyroelectric detector with a flat spectral response. It could be shown that the main challenge is to achieve a high finesse in spite of non-perfect parallelism, mirror curvature and additional phase shift caused by the Bragg reflectors.

The general aim of this project is to realize optical microsystems for NIR spectroscopy (1.5 μm to 2 μm) using the InP/InGaAs material system. We have designed an integrated microspectrometer based on a long-wavelength strained InGaAs quantum well RCE photodiode combined with a wavelength tunability function (MEMS concept). The weak absorption of the QWs is enhanced by embedding the quantum wells into a micromachined tunable vertical resonator that consists of multiple InP/air-gap alternate layers that form both the DBR reflectors and the electrostatically tunable air-gap cavity. The devices are fabricated using a specific MOEMS process based on selective wet etching of an InP/InGaAs epitaxial layer stack grown by MOVPE. The small size and low cost of these microsystems pave the way to promising industrial applications, such as non-invasive biological analysis, on-line industrial process analysis and hyperspectral imaging. The paper focuses on critical design and process issues in order to accommodate residual stresses in the suspended membranes while preserving a suitable tuning range. We present a specific design optimized for the monitoring of sugar concentration in water. The selected spectral range for this analysis is comprised between 1650 nm and 1750 nm.

The development of new MOEMS demands for cooperation between researchers in micromechanics, optoelectronics and microoptics at a very early state. Additionally, microoptical technologies being compatible with structured silicon have to be developed. The microoptical technologies used for two silicon based microsystems are described in the paper. First, a very small scanning laser projector with a volume of less than 2 cm³, which operates with a directly modulated lasers collimated with a microlens, is shown. The laser radiation illuminates a 2D-MEMS scanning mirror. The optical design is optimized for high resolution (VGA). Thermomechanical stability is realized by design and using a structured ceramics motherboard. Secondly, an ultrathin CMOS-camera having an insect inspired imaging system has been realized. It is the first experimental realization of an artificial compound eye. Micro-optical design principles and technology is used. The overall thickness of the imaging system is only 320 μm, the diagonal field of view is 21°, and the f-number is 2.6. The monolithic device consists of an UV-replicated microlens array upon a thin silica substrate with a pinhole array in a metal layer on the back side. The pitch of the pinholes differs from that of the lens array to provide individual viewing angle for each channel. The imaging chip is directly glued to a CMOS sensor with adapted pitch. The whole camera is less than 1mm thick. New packaging methods for these systems are under development.

QUALCOMM has developed and transferred to manufacturing iMoD displays, a MEMS-based reflective display technology. The iMoD array architecture allows for development at wafer scale, yet easily scales up to enable fabrication on flat-panel display (FPD) lines. In this paper, we will describe the device operation, process flow and fabrication, technology transfer issues, and display performance.

Recently, there has been substantial progress in the development of ultra-compact image projection systems with dimensions clearly below the size of products based on DMD^TM technology. This has been enabled by the availability of electrically modulated laser sources for all three elementary colors and a two-dimensional resonant micro scanning mirror as MOEMS device for light deflection. The laser beam formed by collimator optics is directed onto the micro scanning mirror. Then, the reflected beam describes a highly complicated Lissajous figure on the projection screen with flare angles of up to 20 degrees. By driving the mirror and electrically modulating the intensity of the laser beam in a synchronous manner, projection of images can be achieved. In this contribution we will present the theoretical background of the projection system as well as the latest achievements in system design. Both monochrome and full color systems are currently available. The latter use a separate laser bank as RGB light source, which is coupled with the projection head comprising the micro-optics and the micro scanning mirror. For monochrome red systems, the laser diode can be integrated into the projection head as well, whose volume could be reduced to 15mm x 7 mm x 5mm. All systems have VGA (640 x 480 pixels) resolution and operate with 8 bit color depth per pixel and 50 frames per second. This degree of miniaturization makes laser projection systems attractive for integration into mobile devices and overcomes limitations of display size in such appliances.

An electrostatic 1 dimensionally (1D) scanning mirror for HD resolution display is introduced. Vertical comb drive was used to tilt the micro mirror. To minimize the moment of inertia and maximize the tilting angle of the mirror having the diameter of 1.6 mm, the rib was patterned on the backside of the mirror surface and optimized. Via the finite element simulation, the dynamic deformation of 45nm was achieved within the reflecting area in operating resonant mode thanks to the optimized rib structure. The actuating part of scanner was also optimized manipulating with several design variables to get maximum tilting angle. As the fabrication result, mechanical tilting angle of ±12.0 degree was achieved with the resonant frequency of 24.75kHz and the sinusoidal driving voltage of 280Vpp. For stable resonant motion of the scanner, the feedback control algorithm was realized in the driving circuit. Rigorous reliability characterization was carried out using statistical analysis on the fabricated samples. As a result, HD-resolution image with 720 progressive horizontal lines was demonstrated.

In this work we describe the fabrication and characterization of micro-opto-electro-mechanical AND, OR and XOR logic gates based in a combination of optical and micro-electro-mechanical devices. These structures consist of silicon oxynitride-based optical waveguides, through which a light beam of 633-nm can be conducted, and mobile thermo-electro actuated cantilevers, which form part of the waveguide and can work as ON-OFF switches for the laser. These switches are combined to form AND, OR and XOR gates, allowing the laser light to pass or blocking the laser light when activated electrically. The cantilevers are fabricated by freeing regions of the waveguide, which is done by front side micromachining the silicon wafer used as substrate. Also, they are actuated electrically through the heating of a metallic resistance positioned in the device, where the applied current heats the cantilevers and, due to the difference in thermal expansion coefficients of the constituent materials, it is possible to produce a controlled motion proportional to the heating current. Therefore, the switches can be electrically polarized in on/off cycles allowing or blocking the light through the waveguide, similar to logic "1's" and "0's". These switches are adequately arranged to produce an output that is similar to the conventional digital logic gates through electric control (input) of cantilever-based ON-OFF switches.

This paper describes the design, fabrication, and characterization of the first MEMS scanning mirror with performance matching the polygon mirrors currently used for high-speed consumer laser printing. It has reflector dimensions of 8mm X 0.75mm, and achieves 80^o total optical scan angle at an oscillation frequency of 5kHz. This performance enables the placement of approximately 14,000 individually resolvable dots per line at a rate of 10,000 lines per second, a record-setting speed and resolution combination for a MEMS scanner. The scanning mirror is formed in a simple microfabrication process by gold reflector deposition and patterning, and through-wafer deep reactive-ion etching. The scanner is actuated by off-the-shelf piezo-ceramic stacks mounted to the silicon structure in a steel package. Device characteristics predicted by a mathematical model are compared to measurements.

This paper discusses the fracture strength study of torsion springs in MEMS microscanners, which are fabricated in silicon-on-insulator (SOI) with deep-reactive-ion-etch (DRIE) process. High performance microscanners are of particular interest for scanning laser projection displays. To produce high resolution images, scanners are required to rotate with large actuation angles (>10 degrees mechanical angle) at designated resonant frequencies. While the designs are pushed closer to material limits, it is essential to acquire knowledge of single-crystal-silicon's fracture strength. We have designed samples for fracture strength tests, which reach failure angle (> 20 degrees) with low driving voltage (< 50 volts) under vacuum. The tests are performed with real-time optical feedback to ensure resonance operations. A voltage ramp is applied to scanners until fractures occur; the ramp-rate and starting angle are chosen such that failures occur within thirty minutes of operation. Torsional stresses at fracture are calculated from failure angles via an ANSYS(R) model. In the experiment, forty samples from two spring designs with a cross-section of 14x30 um and a length of 240 um are tested. Because fracture angles scatter around a mean value, Weibull statistics is used to treat the characteristic behaviors of the tested samples to better interpret the test results. The Weibull characteristic fracture strengths are 2.97 GPa and 2.58 GPa. With a stress limit of less than 2 GPa, we can achieve a 86% reliability SVGA microscanner design with a 1 mm diameter, a 32 KHz resonance frequency, and a single-side mechanical scan angle of 13 degrees.

A 1.7× VGA zoom camera was designed based on two variable-focus liquid lenses and three plastic lenses. The strongly varying curvature of the liquid/liquid interface in the lens makes an achromatic design complicated. Special liquids with a rare combination of refractive index and Abbe number are required to prevent chromatic aberrations for all zoom levels and object positions. A set of acceptable liquids was obtained and used in a prototype that was constructed according to our design. First photos taken with the prototype show a proof of principle.

This paper presents a dual-axes confocal microscope based on a two-dimensional (2-D) MicroElectroMechanical system (MEMS) scanner. Dual-axes confocal microscopy provides high resolution in both transverse and axial directions, and is also well-suited for miniaturization and integration into endoscopes for in vivo imaging. The gimbaled MEMS scanner is fabricated on a double silicon-on-insulator (SOI) wafer (a silicon wafer bonded on a SOI wafer) and is actuated by self-aligned, vertical, electrostatic combdrives. The reflecting surface of the scanner is covered with a 10-nm aluminum layer. Reflectance and fluorescence imaging is successfully demonstrated in a breadboard setup. Images with a maximum field of view (FOV) of 340 μm x 420 μm are achieved at 8 frames per second. The transverse resolution is 3.9 μm and 6.7 μm for the horizontal and vertical dimensions, respectively.

We present a three-dimensional (3-D) endoscopic optical coherence tomography (OCT) system using a dual axis scanning mirror. The MEMS device employed in this study utilized a 1.2 mm mirror and exhibited x and y-axis resonant frequencies greater than 1 kHz. The developed probe was packaged and integrated with an OCT system which has a scan rate of 3~8 frames/s. Preliminary in vivo and in vitro 3-D OCT images of biological tissue, such as human finger, vocal cord, rabbit trachea, were visualized to verify the achieved performance of the device.

A new two-dimensional and resonantly driven scanning micro mirror has been simulated, fabricated and characterized. Features are a small chip size of 2900 μm x 2350 μm with a frame oscillating at frequencies in the range of 1 kHz. The frame carries a mirror of 500 μm diameter in a gimbal mounting oscillating at frequencies in the range of 16 kHz. The characteristic mechanical amplitudes are 21^o and 28^o respectively. Voltages of 60 V and less than 140 V were necessary to accomplish this. Much higher amplitudes have been achieved on the mirror axis without breaking the torsion bars. Initial difficulties in realizing the high amplitudes have been overcome by improving the geometry of the suspension. The initial design is presented as well as the measurement results of the initial and improved design. The device was used to develop a micro laser camera with high depth of focus. Pictures taken with the system are presented revealing the excellent resolution.

In 2004, Microvision presented "Scanned Beam Medical Imager" as an introduction to our MEMS-based, full color scanned beam imaging system. This presentation will provide an update of the technological advancements since this initial work from 2004. This recent work includes the development of functional prototypes that are much smaller than previous prototypes using a design architecture that is easily scalable. Performance has been significantly improved by increasing the optical field of views and video refresh rate. Real-time image processing capabilities have been developed to enhance the image quality and functionality over a wide range of operating conditions. Actual images of various objects will be presented.

This paper deals with the design, fabrication and characterization of the first spherical artificial compound eye which is capable of obtaining resolvable images. Due to fabrication aspects it is based on a design that is slightly different from the natural archetype: it is comprised of an imaging microlens array and a pinhole array serving as receptors on separate spherical bulk lenses. The structuring of curved surfaces is possible by means of a modified laser lithography system. The ability to take images is proven and captured images are investigated with respect to the size of ghost-free field of view, resolution and angular sensitivity function.

The recently developed two-photon polymerisation technique is used for the fabrication of two- and three-dimensional structures in photosensitive inorganic-organic hybrid material (ORMOCER), in SU8 , and in positive tone resist with resolutions down to 100nm. In this contribution we present applications of this powerful technology for the realization of micromechanical systems and microoptical components. We will demonstrate results on the fabrication of complex movable three-dimensional micromechanical systems and microfluidic components which cannot be realized by other technologies. This approach of structuring photosensitive materials also provides unique possibilities for the fabrication of different microoptical components such as arbitrary shaped microlenses, microprisms, and 3D-photonic crystals with high optical quality.

The paper proposed a novel seesaw structure for elevating the micro optical device by the driving force of micro array thermal actuator, MATA. The effects of elevating structure, lateral connection arm structure, immobile structure and width of vertical connection arm on the maximum displacements and the variation of surface flatness of the elevated micro mirror surface varied with operation voltage are investigated. The motion behavior of the elevated micro mirror is stimulated and analyzed to get the maximum displacement and inclined angle of the device. The results demonstrate a pair of {1 x 2} parallel type MATA for the elevating structure, simple beam for the lateral connection arm structure, single thermal actuator for the immobile structure and 10μm for width of vertical connection arm are the optimum design for the micro optical device. The maximum displacement and inclined angle of the proposed micro optical device are 34.7μm and 10^o, respectively. The device is fabricated by Taiwan Semiconductor Manufacture Cooperation, TSMC 0.35μm 2P4M mixed signal model, based upon CIC CMOS-MEMS process. The paper will examine whether CIC CMOS-MEMS could fully support to fabricate the integrated component for MOEMS.

We discuss the long-term stability of the NIST chip-scale atomic clock (CSAC) physics packages. We identify the major factors that currently limit the frequency stability of our CSAC packages after 100 s. The requirements for the stability of the vapor cell and laser temperature, local magnetic field, and local oscillator output power are evaluated. Due to the small size of CSAC physics package assemblies, advances MEMS packaging techniques for vacuum sealing and thermal isolation can be used to achieve the temperature stability goals. We discuss various ideas on how to aid temperature control solutions over wide variations in ambient temperature by implementing atom-based stabilization schemes. Control of environment-related frequency instabilities will be critical for successful insertion of CSACs into portable instruments in the areas of navigation and communication.

In this paper, we discuss the characteristics of a six-axis, micro-scale nanopositioner and steps that have been taken to adapt it for use in aligning and manipulating micro-optics. This device, the microHexFlex, is designed to possess motion and force characteristics that enable it to align or manipulate small optical elements such as waveguides, diode laser, lenses, fibers, etc... More specifically, a microHexFlex with 3mm diameter footprint has been shown to have a quasi-static range of 7 x 13 x 8 μm³ and 0.9 x 0.8 x 1.4 degrees. Simulations show that the microHexFlex is capable of exerting quasi-static forces of approximately 20mN and 2.7mN along in-, and out-of-plane directions. We discuss how the dynamic performance and resolution of the microHexFlex have been augmented using Input Shaping^TM and HyperBit control respectively. This enables the microHexFlex to rapidly and accurately control position within 10 nm when operating at 100 Hz. The microHexFlex may be manufactured using deep reactive ion etching (DRIE) at a cost of less than $2 dollars per device.

The motion behaviors of the elevation for a pair of micro mirrors connected in opposite are investigated. The driving force of micro array thermal actuator, MATA, is applied for elevating the micro mirrors. The device design is followed Taiwan Semiconductor Manufacture Cooperation, TSMC, 0.35μm 2P4M mixed signal model process design rule. The optimum number of springs and type of MATA are adopted based upon the simulation results. Simple double springs for connecting two mirrors and two pairs of {1x3} parallel type MATA for elevating the micro mirrors are the optimum design. The constricted motion in plane of two pairs of {1x3} parallel type MATA results in the out plane motion of two connected mirrors when the operation voltage is applied on MATA electrodes. The effects of the position of connection springs on the net displacement and the surface flatness of the elevated micro mirror surface varied with operation voltage are investigated. The results demonstrate the net displacement of elevated micro mirror is the largest, when the position of two springs for connecting two micro mirrors is at metal 3. On the other hand, the variation of surface flatness of the elevated micro mirror is relatively significant on the edges where are without any constricted. However, the variation of surface flatness is between 0.2μm and 0.4μm based upon a "C" shape structure layer at the back of mirror in thickness of metal 3. Nevertheless, the variation of surface flatness is below 0.1μm when thickness of supporting structure layer is in thickness of metal 2 and metal 3 due to the high rigidity. When the operation voltage is 7V and the size of single micro mirror is 200μm x 200μm with a "C" shape supporting structure in thickness of metal 3 and metal 2 layers, the net displacement and inclined angle of the proposed micro optical device are 37.4 μm and 10.7^o, respectively.

Fly's eye condensers are commonly used for the beam shaping of an arbitrary input intensity distribution into a top hat. The setup usually consists of a Fourier lens and two identical regular microlens arrays - often referred to as tandem lens array - where the second one is placed in the focal plane of the first microlenses. Due to the periodic structure of the regular arrays the output intensity distribution is modulated by equidistantly located sharp intensity peaks. In a chirped array, the inflexibility of a regular structure has been overcome. Hence, an array can be formed which is non-periodic and consequently the equidistantly located intensity peaks can be suppressed. A far field speckle pattern results with more densely and irregularly located intensity peaks leading to an improved homogeneity of the intensity distribution. In contrast to stochastic arrays, chirped arrays consist of individually shaped lenses defined by a parametric description of the cells optical function which can be derived completely from analytical functions. This gives the opportunity to build up tandem array setups enabling to achieve far field intensity distribution with an envelope of a top hat. We propose a new concept of a fly's eye condenser incorporating a chirped tandem microlens array for the generation of a top hat far field intensity distribution with improved homogenization under coherent illumination. Considerations for the design of the irregular micro lens arrays and measurements of far field intensity distributions obtained from first prototypes generated by reflow of photoresist are presented.

In the analysis and modeling of MEMS devices, a general finite element formulation is necessary to solve a multidisciplinary domain of the device with large number of nodes and elements. In this paper, we present a step by step finite element formulation for automated modeling of multi-disciplinary domains. The electro-thermo-mechanical domain is explained and an algorithmic approach for sequential analysis of an arbitrary ground structure with multi-disciplinary boundaries is developed and implemented in Matlab with a graphical user interface. The results of the finite element approach is compared and verified with exact solutions and test results from literature. The agreement of results verifies the application of proposed finite element formulation to the analysis of elector-thermo-mechanical domains. This formulation provides a fast and reliable tool to analyze electro-thermo-elastic devices which allows large flexibility in the selection of mechanical and electrical boundary conditions.