The Phase-Only Spatial Light Modulator (PLM) is a piston-mode design of the Digital Micromirror Device (DMD) that Texas Instruments DLP® Products has been developing in recent years. While the manufacturing of the PLM shares many of the same process steps of the traditional DMD, the optical system integration of the two devices are fundamentally different. As a result, new optimization is needed to maximize the performance of the PLM based on the device characteristics. This paper covers the optimization of key pixel parameters – array fill factor, mirror flatness, mirror tilt – and generally how the parameters affect a device performance metric we call Zeroth-Order Efficiency. The various improvements are modeled to ascertain expected performance gains and at what point the performance benefits achieve asymptotic behavior. Theoretical and empirical results are shown for the improved key pixel parameters and their corresponding gains made to Zeroth-Order Efficiency.
The Digital Micromirror Device (DMD), developed by Texas Instruments (TI), has been in production for over 25 years. It is a Micro-optical-electro-mechanical system (MOEMS) that functions as a spatial light modulator (SLM) by directing millions of points of light into or out of the projection optics path. TI is now developing a new MOEMS device based on the same processes, equipment sets, and design knowledge as the DMD. This new device operates in a piston mode with each mirror moving up and down instead of rotating left and right as the DMD does. By operating in a piston mode, the mirrors can modulate the phase of light and function as a phase light modulator (PLM). This paper focuses on the reliability of the PLM device. TI has a strong foundation for MOEMS reliability resulting in the mature and reliable DMD. Early results from various life tests and environmental tests confirm that PLM reliability is comparable to DMD reliability. The paper will discuss reliability test results and related performance metrics.
Over the last few years, DLP® Products at Texas Instruments, Inc. has been developing a MEMS-based phase-only spatial light modulator that we call the Phase Light Modulator or PLM. The device which shares many of the process steps with the DLP micromirror device consists of a vertically actuated mirror on top of a CMOS array. The current reflective device provides enough vertical range to be suitable for visible wavelengths. This paper discusses a number of metrics important to the performance of a phase-only spatial light modulator and the corresponding characteristics of the PLM. The metrics include diffraction efficiency, number of phase levels, resolution, speed, and die flatness. The paper also discusses in depth recent design improvements such as increasing the number of phase levels to improve efficiency and reduce image noise. Recent lifetime test results collected over more than 1000 hours are also presented. Finally, there is a discussion of our possible approaches to testing the device in a high-volume production environment.
Piston‐mode Fourier based optical imaging created using an adaptation of the base DLP® Products torsional, spatial light modulator technology is presented. Technology, advancements and performance metrics such as, actuation speed, efficiency, and pixel coupling are shown for this 10.8 μm pitched pixel array. Device potential includes upwards of 5.7kframes/sec actuation.
This JM3 special section on emerging MOEMS comprises a collection of excellent papers emphasizing new technologies in MOEMS applications that have come to existence. The section includes outstanding new results in commercial research and development in photonics where micro-optics and MEMS are merged and innovative breakthrough devices come to light.
This paper describes the business scope to which DLP® Products works under with emphasis placed upon some of the
technological complications and challenges present when developing an actuator array with the ultimate intention of
rendering visual content at high-definition and standard video rates. Additionally, some general thoughts on alternative
applications of this spatial light modulation technology are provided.
Interrogation tools are the key to a thorough understanding of any technology. Texas Instruments' DLP(R) Products - Digital Mirror Device is no exception to this rule. We will discuss the application of a non-destructive, through-glass interferometer system toward gaining insight to the degree of structural uniformity of a statistically significant sampling of micro-opto-electromechanical (MOEM) mirrors as used in our product line. In the course of providing this information, instrumentation details such as reliability and reproducibility of measurements obtained on this interferometer will be discussed. Additionally, the importance of this mechanical uniformity to displaying images with this spatial light modulator (SLM) will be discussed as well.
In this paper the results of detecting volatile organic compounds (VOC) employing surface plasmon-based sensors are presented. The initial step in preparing the sensing elements herein requires depositing Au degree(s) on a quartz slide. The sensing elements are based on either (1) freshly deposited Au degree(s) or (2) growth of a self assembled monolayer composite film (SAM) on to a freshly deposited Au degree(s) surface. The desired SAM is either (1) acid terminated using (omega) -mercaptoundecanoic acid (MUA-COOH) or (2) Cu2+ metal ion terminated yielding (omega) - mercaptoundecanoic acid-Cu2+ (MUA-Cu2+). The experimental apparatus shown here measures the reflectivity of the Au degree(s) surface as a function of time at a given angle. The response of this surface plasmon device to various VOC's is correlated to the composition of the SAM film.
The effects of the local dielectric environment on the surface-plasmon resonances of annealed gold-island films are studied experimentally and modeled theoretically. Gold- island films were annealed at 600 degree(s)C to produce spheroidal shape particles which exhibit well-resolved resonances in polarized, angle-resolved, absorption spectra. These resonances are shifted in different amounts by the depolarization effect of the surrounding medium (liquids with various refraction indices). Cross-section calculations based upon non-retarded, single-particle, dielectric interaction for these various configurations are presented and found to be in good agreement with the experimental observations.
Charles Britton, R. Warmack, S. Smith, Patrick Oden, Gilbert Brown, W. Bryan, Lloyd Clonts, Michael Duncan, Mike Emery, M. Ericson, Z. Hu, Robert Jones, Michael Moore, J. Moore, Jim Rochelle, Timothy Threatt, Thomas Thundat, Gary Turner, Alan Wintenberg
Selectively coated cantilevers are being developed at ORNL for chemical and biological sensing. The sensitivity can exceed that of other electro-mechanical devices as parts- per-trillion detection can be demonstrated for certain species. We are now proceeding to develop systems that employ electrically readable microcantilevers in a standard MEMS process and standard CMOS processes. One of our primary areas of interest is chemical sensing for environmental applications. Towards this end, we are presently developing electronic readout of a mercury-sensitive coated cantilever. In order to field arrays of distributed sensors, a wireless network for data reporting is needed. For this, we are developing on-chip spread-spectrum encoding and modulation circuitry to improve the robustness and security of sensor data in typical interference- and multipath-impaired environments. We have also provided for a selection of distinct spreading codes to serve groups of sensors in a common environment by the application of code-division multiple-access techniques. Most of the RF circuity we have designed and fabricated in 0.5 micrometers CMOS has been tested and verified operational to above 1 GHz. Our initial intended operation is for use in the 915 MHz Industrial, Scientific, and Medical band. This paper presents measured data on the microcantilever-based mercury detector. We will also present design data and measurements of the RF telemetry chip.
Uncooled infrared sensors are significant in a number of scientific and technological applications. A new approach to uncooled infrared detectors has been developed using piezoresistive microcantilevers coated with thermal energy absorbing material(s). Infrared radiation absorbed by the microcantilever detector can be sensitively detected as changes in the electrical resistance as a function of microcantilever bending. These devices have demonstrated sensitivities comparable to existing uncooled thermal detector technologies. The dynamic range of these devices is extremely large due to measurable resistance change obtained with only nanometer level cantilever displacement. Optimization of geometrical properties for selected commercially available cantilevers is presented. Additionally, we present results obtained from a modeling analysis of the thermal properties of several different microcantilever detector architectures.
The feasibility of micromechanical optical and infrared (IR) detection using microcantilevers is demonstrated. Microcantilevers provide a simple means for developing single- and multi-element sensors for visible and infrared radiation that are smaller, more sensitive and lower in cost than quantum or thermal detectors. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress originating from the bimetallic effect. Bending is proportional to the amount of heat absorbed and can be detected using optical or electrical methods such as resistance changes in piezoresistive cantilevers. The microcantilever sensors exhibit two distinct thermal responses: a fast one ((tau) 1thermal less than ms) and a slower one ((tau) 2thermal approximately 10 ms). A noise equivalent temperature difference, NEDT equals 90 mK was measured. When uncoated microcantilevers were irradiated by a low-power diode laser ((lambda) equals 786 nm) the noise equivalent power, NEP, was found to be 3.5 nW/(root)Hz which corresponds to a specific detectivity, D*, of 3.6 multiplied by 107 cm (DOT) (root)Hz/W at a modulation frequency of 20 Hz.
We describe a lithographic technique using atomic force microscopy (AFM) to expose commercially available photoresists in a controllable manner. In contrast to scanning tunneling microscopy lithography on photoresists, the AFM has the advantage of having better control of the contact force between the probe tip and sample and thus reduces the possibility of physical damage to the resist material during exposure. Using a metal coated cantilever, we have been able to create resist patterns at the nanometer-scale.
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