This PDF file contains the front matter associated with SPIE Proceedings Volume 8252, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Magnetically-actuated micromachined scanning mirrors have been developed for pico-projectors using laser beam scanning (LBS). The human vision system readily detects imperfections in a LBS display, which become objectionable when scanned beam trajectory errors have amplitudes on the order of only parts per thousand, depending on the human vision system's sensitivity to the type of error and whether it is static or dynamic. The paper describes the overcoming of such challenges to achieve a high quality LBS projection.

Lemoptix develops next-generation of Micro-Opto-Electromechanical Systems (MOEMS)-based laser scanning and microprojection technologies and products for professional and industrial applications. Lemoptix LSCAN laser scanning micromirrors are designed to be integrated by OEM (original equipment manufacturer) customers into a number of applications such as printers and industrial sensors, enhancing performances and enabling the development of smaller, higher resolution and lower cost products. Lemoptix MVIEW, world's smallest laser microprojection systems are ideal for integration by OEMs and ODMs (original design manufacturers) into various demanding applications such as headup displays in cars or mobile devices. Embedded MVIEW modules will enable the projection of content and information directly from the device on any nearby surface, enabling users to conveniently view and share information and content without the typical limitations of physical displays.

A Scan Head package including two 1D resonant electrostatic driven micro scanning mirrors with piezoresistive position detection was developed. The scanning frequency of the slow and the fast axis is 100Hz and 29,05kHz, allowing WVGA-resolution. Thereby the Scan Head design reduces vertical distortion strongly and can potentially be assembled automatically. In addition FPGA based video processing electronic was developed to improve the sorting of the picture information corresponding to the Lissajous figure with the objective of high picture contrast and a homogeneous brightness.

Speckle can seriously degrade image quality in laser-illuminated projection displays. Various solutions appropriate to small microdisplay-based projectors are presented. Illumination optical system and projection optical system design are discussed in order to better understand the critical constraints of size, power consumption, optical efficiency, and performance. DYOPTYKA's innovative solution, using a phase randomizing deformable mirror, is described.

Based on selected liquid and elastic polymers, Optotune has developed adaptive optical components, such as focus tunable lenses and laser speckle reducers. The lenses range from 2 to 55mm in aperture, are mechanically or electrically actuated and offer a continuous range of focal powers of several 10 diopters. This additional degree of freedom enables the design of compact optical systems, typically with less mechanics. We show how tunable lenses can be used to improve optical designs for imaging and illumination systems in terms of size, quality and speed. The speckle reducers are based on electroactive polymers and offer an extremely compact and low cost solution for removing speckles, which is a key benefit for laser projectors and illumination systems.

Since pico-projectors were starting to become the next electronic "must-have" gadget, the experts were discussing which light-source technology seems to be the best for the existing three major projection approaches for the optical scanning module such as digital light processing, liquid crystal on silica and laser beam steering. Both so-far used light source technologies have distinct advantages and disadvantages. Though laser-based pico-projectors are focus-free and deliver a wider color gamut, their major disadvantages are speckle noise, cost and safety issues. In contrast, projectors based on cheaper Light Emitting Diodes (LEDs) as light source are criticized for a lack of brightness and for having limited focus. Superluminescent Light Emitting Diodes (SLEDs) are temporally incoherent and spatially coherent light sources merging in one technology the advantages of both Laser Diodes (LDs) and LEDs. With almost no visible speckle noise, focus-free operation and potentially the same color gamut than LDs, SLEDs could potentially answer the question which light source to use in future projector applications. In this quest for the best light source, we realized visible SLEDs emitting both in the red and blue spectral region. While the technology required for the realization of red emitters is already well established, III-nitride compounds required for blue emission have experienced a major development only in relatively recent times and the technology is still under development. The present paper is a review of the status of development reached for the blue superluminescent diodes based on the GaN material system.

Fraunhofer IPMS developed a new type of small-sized scanning mirror for Laser projection systems in mobile applications. The device consists of a single crystal mirror plate of 1 mm diameter in a gimbal mounting enabling a bi-resonant oscillation of both axes at a resonance frequency of about 100 Hz and 27 kHz respectively. The mechanical scan angle (MSA) achieved is ± 7° for the slow and ± 12° for the fast axis. The mirror angle position and phase can be read out via two piezo-resistive sensors located at the torsion axes. In order to allow for a minimum device size of the resonantly driven slow axis the sensor of the inner fast axis was connected by a new kind of thin silicon conductors. Those are created by means of an etch stop in TMAH etch and kept as thin as possible in order to reduce their contribution to the mechanical stiffness of the mirror-supporting structures. This new system enables to lead six (or even more) independent electrical potentials onto the moving parts of the device, whereas the mechanical properties are mainly determined by only 2 torsion axes. The devices were subsequently characterized and tested. Technology details, simulation results, pictures of the device and the new conductor structures as well as measurement results are presented.

This paper reports on a net flux sensor being devised as part of a network of meteorological sensors for the acquisition of surface data of Mars. The characteristics of the measuring configuration and source of error that drive the sensor design are examined. The pyranometers and pyrgeometers of the sensor use double platform microbolometers with gold black coating for the measurement of radiative fluxes in the spectral range from 0.3 to 50 μm. The microbolometer detector exhibits a typical responsivity of ~ 1.8×10⁴ V/W and a time constant of ~ 14 ms at the pixel level. The reflectance data confirm that the gold black absorbs more than 98 % of the incident light in the range from 0.2 to 20 μm, while the absorptance exceeds 94% for wavelengths up to 100 μm. The detector transfer function is derived to assist in the characterization of net flux sensor. The experimental sensor modules, which differ in the spectral band and field of view, are designed to be interchangeable on the same node of a sensor network. The network is intended for the evaluation of the sensor performance and measurement configuration in analog field experiments.

Multi-object spectroscopy (MOS) allows measuring infrared spectra of faint astronomical objects that provides information on the evolution of the Universe. MOS requires a slit mask for object selection at the focal plane of the telescope. We are developing MEMS-based programmable reflective slit masks composed of 2048 individually addressable micromirrors. Each micromirror measures 100 × 200 μm² and is electrostatically tilted by a precise angle of at least 20°. The main requirements for these arrays are precise and uniform tilt angle over the whole device, uniformity of the mirror electromechanical behavior, a flat mirror deformation and individual addressing capability of each mirror. This capability of our array is achieved using a line-column algorithm based on an optimized tilt angle/voltage hysteresis of the electrostatic actuator. Micromirror arrays composed of 2048 micromirrors (32 × 64) and modeled for individual addressing were fabricated using fusion and eutectic wafer-level bonding. These micromirrors without coating demonstrated a peak-to-valley deformation less than 8 nm and a tilt angle of 24° for an actuation voltage of 130 V. A first experiment of the linecolumn algorithm was demonstrated by actuating individually 2 × 2 micromirrors. In order, to avoid spoiling of the optical source by the thermal emission of the instrument, the micromirror array has to work in a cryogenic environment. Therefore, these devices were characterized in a cryogenic environment at -111°C and several lines of micromirrors were tilted successfully under these conditions.

A translatory MOEMS actuator with extraordinary large stroke - especially developed for fast optical path length modulation in miniaturized FTIR-spectrometers (FTS) - is presented. A precise translational out-of-plane oscillation at 500 Hz with large stroke of up to 1.2 mm is realized by means of an optimized MEMS design using four pantograph suspensions of the comparative large mirror plate with 5mm diameter. The MOEMS device is driven electro - statically resonant and is manufactured in a CMOS compatible SOI process. Up to ± 600 μm amplitude (typically 1mm stroke) has been measured in vacuum of 30 Pa and 50 V driving voltage for an optimized pantograph design enabling reduced gas damping and higher driving efficiency. For FTS system integration the MOEMS actuator has been encapsulated in a hybrid optical vacuum package. In this paper we discuss the thermal influences of packaging technology on MOEMS behaviors more detail.

Standard FT-IR spectrometers are large, usually static, and expensive and require operation by qualified personnel. The presented development involves achievements in MEMS technologies and electronics design to address size, speed and power requirements and develop a fully integrated miniaturized FT-IR spectrometer. A suitably matched interaction of multiple new components - source, interferometer, detector and control and data processing - develops unique MEMS based spectrometers capable of reliable operation and finally results in compact, robust and economical analyzers. The presented system now aims at a high performance level to measure in the range between 5000-750 cm^-1 at a spectral resolution better than 10 cm^-1. The Michelson interferometer design and the desired performance put several demands on the MOEMS device. Amongst these, a mirror travel of ± 500 μm and a minimal dynamic deformation of < λ/10 peak-to peak in combination with a large mirror aperture of 5 mm were the most challenging goals. However, a signal-to-noise ratio of 1000 is required to qualify a FT-IR system as a sensor for industrial applications e.g. process control. The purpose of the system, presented in this work, is to proof that this is feasible on the basis of MEMS technology and it is demonstrated that most of these specifications could be already met.

A miniature MOEM tunable Fabry-Perot (FP) filter development program to fabricate filters operating over spectral regions from the visible to the longwave infrared has recently succeeded in fabricating filters operating over visible/near infrared wavelength region from 400 to 800 nm. The main objective of this program is to design miniature hyperspectral imagers by placing such a miniature tunable FP filter in front of a commercial focal plane array with a suitable optical train. This novel MOEM filter design is based on using two semitransparent 30-nm thick silver-film mirrors-one fixed and one moving with application of an electrostatic force. The silver films were grown on low-cost thin commercial quartz wafers with low total thickness variation. The moving mirror is held in place by three leaf spring arm structures which were fabricated by wet etching of the quartz substrate. The size of the MOEM device is 18×24 mm². The tunable FP filter has a 6-mm optical aperture. The fixed part has three electrodes to apply voltages and the moving mirror is used as a ground electrode. Au bumps were deposited in both parts in order to control the initial air gap distance and an Au-Au bonding was used to bond the two parts together. The electrostatic actuation changes the spacing between the two mirrors which changes the transmitted wavelength. The spectral imaging performance of MOEM filter was characterized using a tunable source and a CCD camera with suitable optics. This paper describes the MOEM filter, its characteristics and present spectral imaging characterization experiment and results.

Shared shuttle runs are an important factor of the microelectronics business ecosystem, allowing fabless semiconductor companies to access advanced processes and supporting the development of new tools and processes. We report on the creation and progress of a shared shuttle program for access to advanced silicon photonics optoelectronic platforms that we expect will create a similar environment for the field of integrated photonics.

Facing the recent developments in the area of (quasi) continuous wave lasers towards higher power the Fraunhofer IPMS introduces a novel light modulator incorporating an innovative architecture optimized for high laser power applications requiring a fast device. As a novelty each pixel is composed of a number of micro mirrors, aligned in a row. That approach allows for, in principle, very long pixels with uniform surface properties. This concept in turn results in reduction of power density at the light modulator surface and hence opens the way to high power applications allowing power densities in the range of several ten W/cm² at the light modulator surface. Each pixel can be switched to black, white or even arbitrary gray values with very high speed. This paper summarizes the device design, working concept, mechanical properties for both static and dynamic operation, and surface properties. Application relevant subjects as stability under intense laser illumination complete the discussion.

A novel technology is presented for arrays of vertical flaps as optically modulating elements which are actuated electrostatically to horizontal position at low voltages of 30-50V. One application is a reflective display exhibiting a contrast ratio of 1:95. We will also show a) shutters for transmissive devices in an array configuration and b) switchable gratings. A large variety of flap geometries are fabricated such as flat reflective, grating, lens or grid shape. Poly-Si refill of thin high aspect-ratio trenches followed of dry etching of the surrounding material is used to fabricate the flaps suspended by torsion beams.

We show a laser beam shaping device made of a deformable continuous reflective membrane fabricated over a scanning stage. The combination of two actuator schemes enables shaping and smoothing of a laser beam with a unique compact device. It is designed to shape an input laser beam into a flat top or Gaussian intensity profile, to support high optical load and to potentially reduce speckle contrast. One single electrode is needed to deform the whole membrane into multiple sub-reflecting concave elements. The scanning stage is used simultaneously to smooth out the remaining interference patterns. The fabrication process is based on SOI wafer and parylene refilling to enable the fabrication of a 100 % fill factor 5 by 5 mm² deformable membrane. Applications for such device are laser machining and laser display.

We present the use of a large-stroke deformable membrane mirror at 45° incidence to achieve a very compact optical system capable of fast multi-layer focusing in an optical disc unit. The MEMS mirror replaces a lens translation mechanism and liquid crystal compensator, resulting in a single optical element to control both focus depth and compensation of attendant focus-dependent spherical aberration. We outline the membrane optical requirements in terms of stroke and aberration compensation required for multi-layer focusing for current DVD and BD standards. We demonstrate an adjustable range of at least 1.6 μm peak wavefront spherical aberration correction at a membrane displacement of 7 μm, which should be sufficient capability for quadruple layer BDXL™ discs.

Air flow is the dominant damping mechanism for deformable membrane mirrors that are actuated with electrostatic pressure from a counter electrode in close proximity to the flexible membrane. We use cryogenic deep silicon etching to create through-wafer perforations in the backplate in order to control air damping and achieve high-speed focus control. This paper describes both our design approach and device fabrication details. We show that damping can be controlled by selecting the proper hole pattern, and we present experimental and simulated frequency response measurements for small membrane displacements. Also we measured the 95% settling time of a 4 mm diameter mirror subjected to a 10 μm step deflection to be less than 200 μs.

We present a miniature non-mechanical zoom camera using deformable MOEMS mirrors. Bridger Photonics, Inc. (Bridger) in collaboration with Montana State University (MSU), has developed electrostatically actuated deformable MEMS mirrors for use in compact focus control and zoom imaging systems. Applications including microscopy, endomicroscopy, robotic surgery and cell-phone cameras. In comparison to conventional systems, our MEMS-based designs require no mechanically moving parts. Both circular and elliptical membranes are now being manufactured at the wafer level and possess excellent optical surface quality (membrane flatness < λ/4). The mirror diameters range from 1 - 4 mm. For membranes with a 25 μm air gap, the membrane stroke is 10 μm. In terms of the optical design, the mirrors are considered variable power optical elements. A device with 2 mm diameter and 10 μm stroke can vary its optical power over 40 diopters or 0.04mm^∧(-1). Equivalently, this corresponds to a focal length ranging from infinity to 25 mm. We have designed and demonstrated a zoom system using two MOEMS elements and exclusively commercial off-the-shelf optical components to achieve an optical zoom of 1.9x with a 15° full field of view. The total optical track length of the system is 36 mm. The design is approximately 30 mm x 30 mm x 20 mm including the optomechanical housing and image sensor. With custom optics, we anticipate achieving form factors that are compatible with incorporation into cell phones.

This paper presents a variable aperture design based on the microelectrofluidic technology which integrates electrowetting and microfluidics. The proposed microelectrofluidic iris (MEFI) consists of two immiscible fluids and two connected surface channels formed by three transparent plates and two spacers between them. In the initial state, the confined aqueous ring makes two fluidic interfaces, on which the Laplace pressure is same, in the hydrophobic surface channels. When a certain voltage is applied between the dielectric-coated control electrode beneath the three-phase contact line (TCL) and the reference electrode for grounding the aqueous, the contact angle changes on the activated control electrode. At high voltage over the threshold, the induced positive pressure difference makes the TCLs on the 1st channel advance to the center and the aperture narrow. If there is no potential difference between the control and reference electrodes, the pressure difference becomes negative. It makes the TCLs on the 1st channel recede and the aperture widen to the initial state. It is expected that the proposed MEFI is able to be widely used because of its fast response, circular aperture, digital operation, high aperture ratio, and possibility to be miniaturized for variable aperture.

This paper describes the Wavelens technology: a new type of varifocal liquid lenses actuated by electrostatic parallel plates. The main technological steps involved in the fabrication process are discussed and the influences of the membrane material, the electrode size and composition (rigidity and stress) on the optical performance are evaluated in detail. The varifocal lenses were characterized extensively using wave-front measurements. Optical powers of 11m^-1 at 9V (16m^-1 at 10V) are measured on lenses with optical diameters of 3mm. The influence of the electrode size on the optical power is analyzed giving basic design rules for the device performance optimization. No significant optical quality degradation was observed with a low wave front error (<0.15μm) measured on the varifocal lenses.

Miniaturization of image sensors and increase of their resolution creates a demand for new miniature optical components providing classical functions in optics, like auto-focus (AF) and optical image stabilization (OIS). Several routes have been explored in order to realize AF and OIS functions in miniaturized components, for example electro-wetting liquid lenses, MEMS components and liquid crystal (LC) lenses. Our recent attempt to provide OIS with LC lenses showed the possibility to shift an image but limitations appeared. The sectorization of the electrodes generates aberrations due to the discontinuities of the electric field at the junction between two sectors. To overcome these limitations, we propose a new structure featuring a resistive electrode. This structure consists in substrates with thin electrodes joined with a ring-shaped resistive electrode (10kΩ/sq.) made of PEDOT-PSS and etched by oxygen plasma. A high resistivity layer (10MΩ/sq.) is then coated on the optical aperture and the cell is assembled like a classical LC modal lens. With this electrode structure, we succeeded to linearize the electric potential between the electrodes and reduce aberrations of the resulting wavefronts. First we simulated the lens by finite elements method to study the impact of the ring-shaped resistive electrode and to calibrate the physical parameters of each components (metallic electrodes, ring-shaped electrode, high resistivity layer, LC...). Then, we realized lenses and we characterized them in terms of focus, deviation angle and aberrations.

Numerical tools have been widely used in the simulations of the exposure, the post-exposure bake, and the development processes in lithography of thick photoresist. Three-dimensional (3D) cellular automata (CA) model has also been successfully introduced for resist etching process simulation in recent years. In this paper, we report a 3D CA model to simulate the formation process of the surface profile of out-of-plane microlens fabricated using ultraviolet (UV) lithography of thick SU-8 resist. The simulation results were compared with experimental results. The comparison shows that the 3D CA model can be used to simulate the complicated surface formation process of the microlenses during the development process.

For MOEMS devices which do not have intrinsic on-chip feedback, position information can be provided with optical methods, most simply by using a reflection from the backside of a MOEMS scanner. Measurement of timing signals using fast differential photodiodes can be used for resonant scanner mirrors performing sinusoidal motion with large amplitude. While this approach provides excellent accuracy it cannot be directly extended to arbitrary trajectories or static deflection angles. Another approach is based on the measurement of the position of the reflected laser beam with a quadrant diode. In this work, we present position sensing devices based on either principle and compare both approaches showing first experimental results from the implemented devices

In this paper we present closed-loop control for accurate positioning of micro optical mechanical system (MOEMS) based scanner mirrors. An analog and a microcontroller based implementation of the control loop have been implemented and are presented in this paper. In particular, the measured results are compared to the characteristics of the devices when driven in open loop mode. Settlings times and operating bandwidth can be improved by a factor of 10 compared to open loop operation. Digital implementations have advantages in terms of flexibility, but show limitations for fast signals due to time discretization.

This paper describes in detail our concept of quasi-static micro scanning mirrors enabling large static deflections and linearized scanning using vertical out-of-plane comb drives. The vertical comb configuration is realized from a planar scanner substrate by wafer bonding. The device concept is highly flexible by design; different kinds of vertical combs (e.g. staggered and angular) can be realized without changing the technological process flow but by design modifications, only. First demonstrator devices are presented: a) quasi-static 1D-scanners with 4 mm mirror diameter and ±7.5° mechanical tilt angle for beam steering and b) a quasi-static / resonant 2D-scanner enabling 2D raster scanning with SVGA resolution.

This work reports the experimental validation of a novel one-dimensional microscanner. The composite cantilever device implements thermoelastic resonant actuation using temperature gradients induced across two frequency-selective directions as a strategy to increase operating speed and decrease damping. The device was fabricated using 0.35-μm CMOS technology and aspect ratio dependent etch modulation. Resonance peaks were measured around 6.4 and 44.7 kHz at atmospheric-pressure conditions; the power sensitivities (2.8 and 1.6 °/W) of the device may compromise its performance for low-power, large-angle applications. Ultimately, the device is suitable for applications requiring a variation from low- to high-stability conditions with increasing operating speed.

Several applications of optical micromirrors need synchronization of its mechanical oscillation with an external control signal. Self-sustained oscillation of micromirrors is a prerequisite for achieving such synchronization. To suppress its mechanical deformation these micromirrors are operated under atmospheric or controlled pressure environment. Operation under this environment leads to increase in driving voltages to achieve required deflections. However, significant parasitic crosstalk due to these high driving voltages presents a challenge for achieving their self-sustained oscillations. In this paper, stable self-sustained oscillation of a 13.5kHz micromirror is achieved at atmospheric pressure by actively suppressing its crosstalk. Frequency stability of 7.2ppm is obtained for this micromirror's self-sustained oscillation at atmospheric pressure.

20 Mega-Hertz-switching high speed image shutter device for 3D image capturing and its application to system prototype are presented. For 3D image capturing, the system utilizes Time-of-Flight (TOF) principle by means of 20MHz high-speed micro-optical image modulator, so called 'optical shutter'. The high speed image modulation is obtained using the electro-optic operation of the multi-layer stacked structure having diffractive mirrors and optical resonance cavity which maximizes the magnitude of optical modulation. The optical shutter device is specially designed and fabricated realizing low resistance-capacitance cell structures having small RC-time constant. The optical shutter is positioned in front of a standard high resolution CMOS image sensor and modulates the IR image reflected from the object to capture a depth image. Suggested novel optical shutter device enables capturing of a full HD depth image with depth accuracy of mm-scale, which is the largest depth image resolution among the-state-of-the-arts, which have been limited up to VGA. The 3D camera prototype realizes color/depth concurrent sensing optical architecture to capture 14Mp color and full HD depth images, simultaneously. The resulting high definition color/depth image and its capturing device have crucial impact on 3D business eco-system in IT industry especially as 3D image sensing means in the fields of 3D camera, gesture recognition, user interface, and 3D display. This paper presents MEMS-based optical shutter design, fabrication, characterization, 3D camera system prototype and image test results.

We present fabrication and characterization of wavelength selective germanium dielectric supported microbolometers using a self-alignment technique to help insure a flat microbolometer membrane. The fabricated microbolometer consists of a resistive absorber sheet on a quarter wavelength germanium layer above a half wavelength air gap, producing dielectric interference [1]. We use a self-aligned process without a polyimide patterning process that helps eliminate deformation and stress in the structure membrane. We demonstrated that the fabricated wavelength selective microbolometers have flat, robust membranes and produce excellent tunable narrowband absorption in MWIR/LWIR band with efficient multi-color IR spectral response using wavelength selective pixels.

Water droplets are an attractive medium to realize visible-frequency optical elements. The smoothness of a droplet surface mitigates losses due to light scattering, the shape of a water droplet is reconfigurable by either applying pressure or a potential, water is nearly transparent over the visible frequency range, and water is highly abundant. Here, we explore a simple methodology to dispense and shape water droplets for application as the magnifying element in a microscope using either reflection-mode or transmission-mode illumination. A water droplet is created at the end of a syringe and then coated with a thin layer of silicone oil to mitigate evaporation. By applying mechanical pressure to the water droplet using a metal tip, the shape of the droplet is tuned to yield focusing properties amenable for microscopy. Images captured using the microscope demonstrate micron-scale resolution, variable magnification, and imaging quality comparable to that obtained by a conventional, laboratory-grade microscope.

The Long Wave IR camera market has grown significantly in the last ten years thanks to the strong cost reduction brought by low cost IR detectors/ microbolometers. This led to the development of many new commercial markets and it is expected that IR camera volumes will be multiplied by 4 to reach 1.18 M units in 2016 thanks to the strong price reduction of the cameras meaning +29% CAGR in volume. The uncooled IR camera revenues will grow from $2.1B in 2010 to $3.4 B in 2016. In our paper, we have both analyzed market and technical trends for uncooled infrared imagers' civilian and military applications.