Steven Lawrence Solomon

MIRAGE: System overview and status

Santa Barbara Infrareds (SBIR) MIRAGE (Multispectral InfraRed Animation Generation Equipment) is a state-of-the-art dynamic infrared scene projector system. Imagery from the first MIRAGE system was presented to the scene simulation community during last years SPIE AeroSense 99 Symposium. Since that time, SBIR has delivered five MIRAGE systems. This paper will provide an overview of the MIRAGE system and discuss the current status of the MIRAGE. Included is an update of system hardware, and the current configuration. Proposed upgrades to this configuration and options will be discussed. Updates on the latest installations, applications and measured data will also be presented.

MIRAGE: developments in IRSP system development, RIIC design, emitter fabrication, and performance

Santa Barbara Infrareds (SBIR) family of MIRAGE infrared scene projection systems is undergoing significant growth and expansion. The first lot of production IR emitters is in fabrication at Microelectronics Center of North Carolina/Research and Development Institute (MCNC-RDI), the state-of-the-art MEMS foundry and R&D center which completed prototype fabrication in early 2003. The latest emitter arrays are being produced in support of programs such as Large Format Resistive Array (LFRA) and MIRAGE 1.5, MIRAGE II, and OASIS. The goal of these new development programs is to increase maximum scene temperature, decrease radiance rise time, support cryogenic operation, and improve operability and yield. After having completed an extremely successful prototype run in 2003, SBIR and MCNC-RDI have implemented a variety of emitter process improvements aimed at maximizing performance and process yield. SBIR has also completed development and integration of the next-generation MIRAGE command and control electronics (C&CE), an upgraded calibration radiometry system (CRS), and has developed test equipment and facilities for use in MIRAGE device wafer probing, test, evaluation, diagnostic, and assembly processes. We present the latest emitter performance data, an overview of emitter foundry processing and packaging improvements, and an update on MIRAGE II, LFRA, and OASIS development programs.

Near-infrared arrays for SIRTF, the Space Infrared Telescope Facility

SIRTF, and other infrared space astronomy projects, require detector arrays with extremely high sensitivity. It is a goal of SIRTF to achieve background limited performance at all wavelengths. Especially critical is the spectral region around 3 micrometers , where the detector current due to the zodiacal background radiation is a minimum. For background limited operation, at a spectral resolution of 100, the dark current must be less than 0.1 e-/s/pixel. The detector noise must be less than the noise given by fluctuations in the number of zodiacal background photons (< 9 e-/pixel). Other detector array goals include: high quantum efficiency (> 90%), radiation hardness, minimal image latency, and excellent photometric accuracy and stability. Many of the performance goals have been met with Santa Barbara Research Centers 256 X 256 InSb arrays.

MIRAGE emitter improvements & technology review

With the increased demand for IR sensor and surveillance systems, there is a growing need for technologies to support their operational readiness. Measurement of sensor characteristics such as sensitivity, MRTD, and dynamic range should be standard in all mission critical systems. The Real-Time Infrared Test Set (RTIR) is a portable system designed to provide in-the-field calibration and testing of IR imaging systems and seekers. RTIR uses the high volume manufacturing processes of the Very Large Scale Integration (VLSI) and the Micro Electromechanical Systems (MEMS) technology to produce a Thermal Pixel Array (TPA). State-of-the-art CMOS processes define all the necessary on-chip digital and analog electronics. When properly driven, this array generates variable temperature,synthetic IR scenes. A nonuniformity measurement of several TPAs is presented.

Investigation of charge-trapping effects in InSb focal plane arrays

We are investigating trapping/recombination centers in near-infrared (1 - 5 micrometers ) InSb imaging arrays via experimentation and theoretical modeling. The presence of impurities, lattice defects and/or surface states can compromise the operational qualities of an imaging array by introducing latent images, signal rate/quantum efficiency loss at low signal levels, and by increasing noise and dark current. Identification of these trapping centers should enable a reduction in their number density by appropriate changes in the material processing and fabrication steps. We have performed experiments and analyses on both gate-controlled arrays (SiOx surface passivation) and recently received gateless arrays (Si3N4 surface passivation). All of the gated arrays showed latent images at temperatures 6 - 26 K for signal fluxes as low as 1500 e-/s/pixel, while neither of the two gateless arrays examined has shown latent images in the same temperature range; no latent image was detected (to a level of < 50 e-) in a 5 second integration after exposure to a 2 X 106 e-/sec/pixel signal flux. We interpret this as evidence for surface state charge trapping in the region of the gate oxide, which is largely eliminated by the new passivation. The physics of surface states is investigated theoretically in order to gain an understanding of the surface contribution to the observed behavior, and a model is presented to explain the experimental results.

Sparse interferometric millimeter-wave array for centimeter-level 100-m standoff imaging

We present work on the development of a long range standoff concealed weapons detection system capable of imaging under very heavy clothing at distances exceeding 100 m with a cm resolution. The system is based off a combination of phased array technologies used in radio astronomy and SAR radar by using a coherent, multi-frequency reconstruction algorithm which can run at up to 1000 Hz frame rates and high SNR with a multi-tone transceiver. We show the flexible design space of our system as well as algorithm development, predicted system performance and impairments, and simulated reconstructed images. The system can be used for a variety of purposes including portal applications, crowd scanning and tactical situations. Additional uses include seeing through dust and fog.

Versatile plasma display technology for UV-visible scene projector

The results of testing two technologies based on gas microplasmas for the generation of UV-visible light is detailed. A microcavity device from the University of Illinois at Champaign-Urbana have been delivered with an Ar/D2 gas mixture. Emission from the Ar/Ne as well as an Ar/D2 eximer in the 250-400nm range, as well as argon lines in the visible and near infrared, are measured. Development of addressing arrays is discussed as is the potential of emission in other wavebands with other gas species. A 100x40 array of plasmaspheres combined with electronics capable of projecting images at 1000 Hz with 10 bits of grayscale resolution has been built and tested. This system, built by Imaging Systems Technology (IST), is capable of accepting DVI output from a HWIL system and projecting UV from a gas captured in the spheres. This array uses an argon neon gas mixture to produce UV, visible and near infrared light. Performance data discussed for both arrays include: maximum and minimum brightness, uniformity, spectral content, speed, linearity, crosstalk, resolution, and frame rate. Extensions of these technologies to larger arrays with wider spectral bandwidth for use in multispectral projectors are discussed.

Visible/UV image projector for sensor testing

Microplasma arrays for solar blind ultraviolet scene generation are being investigated in a Phase II SBIR program. An overview of the project and current status is presented. Preliminary work indicates that high flux with either spectral line or broadband radiant emission is possible. Two separate design approaches are being evaluated with array formats up to 100x100 planned for testing. Spectral emission from plasmas formed by multiple gas species have been characterized and several chosen for use in arrays. Design trades between parameters such as: frame rate, # bits of resolution, input power, flux levels, and gas species will be evaluated. The performance of a future system will be estimated.

High temperature materials for resistive infrared scene projectors

Joule heated resistive emitter arrays are presently limited to pixel temperatures on the order of 1000 K. A phase 2 SBIR program is underway to develop material sets with the goal of increasing the operating temperatures of these arrays by up to a factor of 3. Preliminary work indicates that transition metal oxides and carbides are the most promising materials for 3000 K pixel temperatures. An overview of the project and current status is presented. Thin films will be deposited by numerous vendors using a variety of techniques, and annealed at ultra-high temperatures in vacuum to select the most stable materials. Test emitter pixel arrays will be fabricated and tested.

Continuing adventures in high-temperature resistive emitter physics and materials

The next generation of resistively heated emitter pixels will be required to attain MWIR apparent temperatures on the order of 2000K, which will require pixel temperatures on the order of 3000K. Numerical simulations have been carried out to determine the material properties required to support the desired performance. Research has been performed to identify a set of potential materials for fabricating these devices based on materials science, existing thermophysical properties, thermodynamic stability and compatibility with thin film processing.