Micro Air Vehicles (MAVs) operate with many inter-related constraints, including size, weight, power, processing, and
communications bandwidth. Basic equations can be used to provide initial estimates of subsystem parameters that are
consistent with the targeted size and related parameters. For most current MAVs, the power source of choice is
batteries, and the choice of battery type and size will determine the maximum duration of a flight. In this study, first
order models for both rotary wing MAVs and crawling ground platforms are used to determine the optimum battery size
for maximum endurance, given typical parameter values for a 15-cm scale robotic platform. Results indicate that most
micro robotic platforms use battery sizes significantly different than optimum.
The US Army Research Laboratory has assembled a Collaborative Technology Alliance (CTA) for the development of
Micro Autonomous Systems and Technology (MAST). It is envisioned that an ensemble of microsystems with
autonomous behavior will improve situational awareness for a wide range of small unit operations, especially in urban
environments. Due to the breadth of missions and scale of the systems, the MAST program has a profound need to
pursue microsystem designs that simultaneously optimize multifunctionality, robustness, adaptability as well as
affordability. Our inspiration comes from animal physiology, which contains many examples of components that
support multiple functions and capabilities in a highly integrated, efficient fashion. Here we outline our approach for
designing both individual microsystems and a system of microsystems based on inspiration from biology.
KEYWORDS: Staring arrays, Quantum well infrared photodetectors, Sensors, Video, Thermography, Quantum wells, Polarization, Simulation of CCA and DLA aggregates, Infrared radiation, Electrons
A polarization-sensitive thermal imager has been assembled using a quantum-well infrared photodetector (QWIP) focal plane array (FPA) with peak responsivity in the long-wave infrared (LWIR) spectral band near 9 micrometer. Polarization-dependent responsivity is achieved by etching linear gratings onto each pixel during QWIP FPA fabrication, with adjacent pixels having orthogonal grating orientation. The direct integration of the gratings with the pixels eliminates all pixel registration errors encountered with previous infrared polarimetry instruments. We present here details of the FPA and thermal imaging system design and performance and show examples of polarization-enhanced imagery.
We report the result of intersubband absorption measurement on a series of doped quantum-well samples and the determination of both the nonparabolicity parameters and the conduction band/valence band offset ratio of the GaAs/(AlGa)As material system. Absorption spectra were obtained in an FTIR spectrometer for samples with nominal quantum-well widths of 4.0, 4.5, 5.0, 7.5, 10.0, and 15.0 nm and for a series of miniband-transport quantum-well IR photodetectors. X-ray diffraction was used to determine quantum well and barrier thicknesses and the Al mole fraction x of the (Al,Ga)As barrier layers. Absorption measurements were made at temperatures of 295 K and 77 K. An empirical two-band model with an energy-dependent effective mass was used to calculate energy levels, transition energies, and spectral lineshapes for the quantum-well structures. Parameter values for nonparabolicity and band offset ratio were determined by comparison of calculated transition energies to measured spectral data.
Infrared sensor technology is critical to many commercial and military defense applications. Traditionally, cooled infrared material systems such as indium antimonide, platinum silicide, mercury cadmium telluride, and arsenic doped silicon (Si:As) have dominated infrared detection. Improvement in surveillance sensors and interceptor seekers requires large size, highly uniform, and multicolor IR focal plane arrays involving medium wave, long wave, and very long wave IR regions. Among the competing technologies are the quantum well infrared photodetectors based on lattice matched or strained III-V material systems. This paper discusses cooled IR technology with emphasis on QWIP and MCT. Details will be given concerning device physics, material growth, device fabrication, device performance, and cost effectiveness for LWIR, VLWIR, and multicolor focal plane array applications.
Quantum well infrared photodetector (QWIP) technology has developed rapidly in the past decade culminating in the demonstration of large format focal plane arrays. Most of the efforts so far have been on tactical applications in which an increased operating temperature is the major objective. For strategic applications with a cold background and a faint target, low temperature operation is required. Under these conditions, improving the conversion efficiency (quantum efficiency times gain) is very important for QWIPs to collect sufficient signal. Simplified QWIP (S-QWIP) structures with increased optical gains have been demonstrated. In this presentation, experimental results of several S-QWIPs will be given. The properties of simplified QWIPs will be examined at low temperatures with a low background and a faint target. Results of a computer simulation with an unresolved target will be discussed.
We describe here a study of Mini-Band Transport (MBT) Quantum Well Infrared Photodetector (QWIP) samples in which the binding energy of photoexcited electrons is systematically varied. Each sample has been characterized electrically and radiometrically. Results are reported for variation of absorption spectra, spectral response, IV characteristics, blackbody responsivity, detector noise, and detectivity vs. binding energy for dark current limited mode of operation.
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