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This PDF file contains the front matter associated with SPIE Proceedings Volume 9854, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
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Novel Image Sensing Technologies and Applications I
Abstract—We report low-noise avalanche gain from photodiodes composed of a previously uncharacterized alloy, AlxIn1-xAsySb1-y, grown lattice-matched on GaSb substrates. By varying the aluminum content the direct bandgap can be tuned from 0.25 eV (0% aluminum) to 1.24 eV (75% aluminum), corresponding to photon wavelengths from 5000 nm to 1000 nm, with the transition from direct-gap to indirect-gap occurring at ~1.18 eV (~72% aluminum), or 1050 nm. This has been used to fabricate separate absorption, charge, and multiplication (SACM) APDs using Al0.7In0.3As0.3Sb0.7 for the multiplication region and Al0.4In0.6As0.3Sb0.7 for the absorber. Gain values as high as 100 have been achieved and the excess noise factor is characterized by a k value of 0.01, which is comparable to or below that of Si. In addition, since the bandgap of the absorption region is direct, its absorption depth is 5 to 10 times shorter than indirect-bandgap silicon, potentially enabling significantly higher operating bandwidths.
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The reflection loss in imaging devices is one of the major drawbacks, which degrades efficiency resulting in lower responsivity. Since the reflected light is no longer available for conversion into electrons, it is very important to reduce the reflection from the top surface of the device as much as possible. Quarter wavelength and two index antireflection (AR) coatings have been developed to reduce reflection; however, these AR coatings are wavelength dependent and have not performed effectively in a broadband range. Attempts to make AR coating for broadband wavelengths by stacking multiple index AR layers result in thicker and expensive solutions, which still do not provide proper antireflection at all desired wavelengths. Moreover, the usage of AR coatings escalates material and fabrication costs of the device. We propose a novel nanostructure, which matches the refractive index of the device to that of free space to reduce reflection from the top surface, eliminating the use of AR coatings and hence reducing the device cost. It is shown via simulation that the proposed nanostructure effectively eliminates the reflection loss over the broadband spectrum of desired wavelengths e.g. Visible, Mid-wave IR (MWIR), Short-wave IR (SWIR) spectrums, opening various application opportunities.
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Electro-optical/infrared (EO/IR) nanosensors are being developed for a variety of defense and commercial systems applications. One of the critical technologies that will enhance EO/IR sensor performance is the development of advanced antireflection coatings. In this paper, we review our latest work on high quality nanostructure-based antireflection structures, including recent efforts to deposit nanostructured antireflection coatings on IR substrates. Nanostructured antireflection coatings fabricated via oblique angle deposition are shown to enhance the optical transmission through transparent windows by minimizing reflection losses at the spectral band of interest to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies. Step-graded antireflection structures also exhibit excellent omnidirectional performance, and have recently been demonstrated with good performance in medium wavelength and long wavelength IR spectral bands.
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Photodetectors based on germanium which do not require cooling and can provide good near-infrared (NIR) detection performance offer a low-cost alternative to conventional infrared sensors based on material systems such as InGaAs, InSb, and HgCdTe. As a result of the significant difference in thermal expansion coefficients between germanium and silicon, tensile strain incorporated into Ge epitaxial layers deposited on Si utilizing specialized growth processes can extend the operational range of detection to 1600 nm and longer wavelengths. We have fabricated Ge based PIN photodetectors on 300 mm diameter Si wafers to take advantage of high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology. This device fabrication process involves low temperature epitaxial deposition of Ge to form a thin p+ (boron) Ge seed/buffer layer, and subsequent higher temperature deposition of a thicker Ge intrinsic layer. This is followed by selective ion implantation of phosphorus of various concentrations to form n+ Ge regions, deposition of a passivating oxide cap, and then top copper contacts to complete the PIN detector devices. Various techniques including transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have been employed to characterize the material and structural properties of the epitaxially grown layers and fabricated detector devices, and these results are presented. The I-V response of the photodetector devices with and without illumination was also measured, for which the Ge based photodetectors consistently exhibited low dark currents of around ~1 nA at -1 V bias.
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Banpil Photonics has developed a high-performance Digital Read-Out Integrated Circuit (DROIC) for image sensors and camera systems targeting various military, industrial and commercial Infrared (IR) imaging applications. The on-chip digitization of the pixel output eliminates the necessity for an external analog-to-digital converter (ADC), which not only cuts costs, but also enables miniaturization of packaging to achieve SWaP-C camera systems. In addition, the DROIC offers new opportunities for greater on-chip processing intelligence that are not possible in conventional analog ROICs prevalent today. Conventional ROICs, which typically can enhance only one high performance attribute such as frame rate, power consumption or noise level, fail when simultaneously targeting the most aggressive performance requirements demanded in imaging applications today. Additionally, scaling analog readout circuits to meet such requirements leads to expensive, high-power consumption with large and complex systems that are untenable in the trend towards SWaP-C. We present the implementation of a VGA format (640x512 pixels 15μm pitch) capacitivetransimpedance amplifier (CTIA) DROIC architecture that incorporates a 12-bit ADC at the pixel level. The CTIA pixel input circuitry has two gain modes with programmable full-well capacity values of 100K e- and 500K e-. The DROIC has been developed with a system-on-chip architecture in mind, where all the timing and biasing are generated internally without requiring any critical external inputs. The chip is configurable with many parameters programmable through a serial programmable interface (SPI). It features a global shutter, low power, and high frame rates programmable from 30 up 500 frames per second in full VGA format supported through 24 LVDS outputs. This DROIC, suitable for hybridization with focal plane arrays (FPA) is ideal for high-performance uncooled camera applications ranging from near IR (NIR) and shortwave IR (SWIR) to mid-wave IR (MWIR) and long-wave IR (LWIR) spectral bands.
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Optical sensing technology is critical for optical communication, defense and security applications. Advances in optoelectronics materials in the UV, Visible and Infrared, using nanostructures, and use of novel materials such as CNT and Graphene have opened doors for new approaches to apply device design methodology that are expected to offer enhanced performance and low cost optical sensors in a wide range of applications. This paper is intended to review recent advancements and present different device architectures and analysis. The chapter will briefly introduce the basics of UV and Infrared detection physics and various wave bands of interest and their characteristics [1, 2] We will cover the UV band (200-400 nm) and address some of the recent advances in nanostructures growth and characterization using ZnO/MgZnO based technologies and their applications. Recent advancements in design and development of CNT and Graphene based detection technologies have shown promise for optical sensor applications. We will present theoretical and experimental results on these device and their potential applications in various bands of interest.
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Novel Image Sensing Technologies and Applications II
Bulk-grown CdZnTe (Zn = 3%) substrates are the natural choice for HgCdTe epitaxy since it is lattice matched to long wave LW-HgCdTe alloy. However, lack of large area CdZnTe substrates, high production costs, and more importantly, the difference in thermal expansion coefficients between CdZnTe and silicon Read out Integrated Circuits (ROIC) are some of the inherent drawbacks of CdZnTe substrates. Consequently, Hg1-xCdxTe detectors fabricated on silicon substrates are an attractive alternative. Recent developments in the molecular beam epitaxy (MBE) buffer layer growth technology on Si substrates has revolutionized the HgCdTe research and offered a new dimension to HgCdTe-based IR technology. Si substrates provide advantages in terms of relatively large area (3 to 6-inch diameter is easily obtained) compared to CZT substrate materials, durability during processing, and reliability to thermal cycling. Innovations in Si-based composite substrates made it possible to fabricate very large-format IR arrays that offer higher resolution, low-cost arrays and more dies per wafer. Between Si substrates and HgCdTe has large lattice mismatch of 19%. This leads to dislocation densities of low-107 cm-2 for optimal growth of HgCdTe on silicon-based substrates as compared to the mid-104 cm-2 dislocation density of HgCdTe grown on CdZnTe. This paper present dislocation reduction by two orders of magnitude using thermal cycle anneal under Hg environment on HgCdTe grown on Si substrates and as well as defect reduction in Cd(Se)Te buffer layers grown on Si Substrates.
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AIM has developed SWIR modules including FPAs based on liquid phase epitaxy (LPE) grown MCT usable in a wide range of hyperspectral imaging applications. Silicon read-out integrated circuits (ROIC) provide various integration and readout modes including specific functions for spectral imaging applications. An important advantage of MCT based detectors is the tunable band gap. The spectral sensitivity of MCT detectors can be engineered to cover the extended SWIR spectral region up to 2.5μm without compromising in performance. AIM developed the technology to extend the spectral sensitivity of its SWIR modules also into the VIS. This has been successfully demonstrated for 384x288 and 1024x256 FPAs with 24μm pitch. Results are presented in this paper. The FPAs are integrated into compact dewar cooler configurations using different types of coolers, like rotary coolers, AIM’s long life split linear cooler MCC030 or extreme long life SF100 Pulse Tube cooler. The SWIR modules include command and control electronics (CCE) which allow easy interfacing using a digital standard interface. The development status and performance results of AIM’s latest MCT SWIR modules suitable for hyperspectral systems and applications will be presented.
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Graphene has amazing abilities due to its unique band structure characteristics defining its enhanced electrical capabilities for a material with the highest characteristic mobility known to exist at room temperature. The high mobility of graphene occurs due to electron delocalization and weak electron phonon interaction making graphene an ideal material for electrical applications requiring high mobility and fast response times. In this paper, we are going to focus on the benefits along with some of the limitations with using graphene in infrared (IR) devices, electro-optic (EO) devices, and field effect transistors (FET) for radio frequency (RF) applications.
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We report the development and initial testing of the Lockheed Martin first-article, single-stage, compact, coaxial, Fast Cooldown Pulse Tube Microcryocooler (FC-PTM). The new cryocooler supports cooling requirements for emerging large, high operating temperature (105-150K) infrared focal plane array sensors with nominal cooling loads of ~300 mW @105K @293K ambient. This is a sequel development that builds on our inline and coaxial pulse tube microcryocoolers reported at CEC 20137, ICC188,9, and CEC201510. The new FC-PTM and the prior units all share our long life space technology attributes, which typically have 10 year life requirements1. The new prototype microcryocooler builds on the previous development by incorporating cold head design improvements in two key areas: 1) reduced cool-down time and 2) novel repackaging that greatly reduces envelope. The new coldhead and Dewar were significantly redesigned from the earlier versions in order to achieve a cooldown time of 2-3 minutes-- a projected requirement for tactical applications. A design approach was devised to reduce the cold head length from 115mm to 55mm, while at the same time reducing cooldown time. We present new FC-PTM performance test measurements with comparisons to our previous pulse-tube microcryocooler measurements and design predictions. The FC-PTM exhibits attractive small size, volume, weight, power and cost (SWaP-C) features with sufficient cooling capacity over required ambient conditions that apply to an increasing variety of space and tactical applications.
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The promise of infrared (IR) imaging attaining low-cost akin to CMOS sensors success has been hampered by the inability to achieve cost advantages that are necessary for crossover from military and industrial applications into the consumer and mass-scale commercial realm despite well documented advantages. Banpil Photonics is developing affordable IR cameras by adopting new strategies to speed-up the decline of the IR camera cost curve. We present a new short-wave IR (SWIR) camera; 640x512 pixel InGaAs uncooled system that is high sensitivity low noise (<50e-), high dynamic range (100 dB), high-frame rates (> 500 frames per second (FPS)) at full resolution, and low power consumption (< 1 W) in a compact system. This camera paves the way towards mass market adoption by not only demonstrating high-performance IR imaging capability value add demanded by military and industrial application, but also illuminates a path towards justifiable price points essential for consumer facing application industries such as automotive, medical, and security imaging adoption. Among the strategic options presented include new sensor manufacturing technologies that scale favorably towards automation, multi-focal plane array compatible readout electronics, and dense or ultra-small pixel pitch devices.
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Weather satellite instruments require detectors with a variety of wavelengths ranging from the visible to VLWIR. The Cross-track infrared Sounder (CrIS) is a Polar Orbiting interferometric sensor that measures earth radiances at high spectral resolution, using the data to provide pressure, temperature and moisture profiles of the atmosphere. The pressure, temperature and moisture sounding data are used in weather prediction models that track storms, predict levels of precipitation etc. The CrIS instrument contains SWIR (λc ~ 5 μm at 98 K), MWIR (λc ~ 9 μm at 98 K) and LWIRs (λc ~ 15.4 μm at 81 K) bands in three Focal Plane Array Assemblies (FPAAs).
CrIS detectors are 850 μm diameter detectors with each FPAA consisting of nine photovoltaic detectors arranged in a 3 x 3 pattern. Molecular beam epitaxy (MBE)-grown Hg1-xCdxTe material are used for the detectors fabricated in a modified Double Layer Planar Heterostructure (DLPH) architecture. Each detector has an accompanying cold preamplifier. SWIR and MWIR FPAAs operate at 98 K and the LWIR FPAA at 81 K, permitting the use of passive radiators to cool the detectors. D* requirements at peak 14.01 μm wavelength are ≥ 5.0E+10 Jones for LWIR, ≥ 7.5E+10 Jones at 8.26 μm for MWIR and ≥ 3.0E+11 Jones at peak 4.64 μm wavelength for SWIR. All FPAAs exceeded the D* requirements. Measured mean values for the nine photodiodes in each of the LWIR, MWIR and SWIR FPAAs are D* = 5.3 x 1010 cm-Hz1/2/W at 14.0 μm, 9.6 x 1010 cm-Hz1/2/W at 8.0 μm and 3.4 x 1011 cm-Hz1/2/W at 4.64 μm.
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Novel THz Image Sensing Technologies and Applications I
We report Independent Component Analysis (ICA) technique applied to THz spectroscopy and imaging to achieve a blind source separation. A reference water vapor absorption spectrum was extracted via ICA, then ICA was utilized on a THz spectroscopic image in order to clean the absorption of water molecules from each pixel. For this purpose, silica gel was chosen as the material of interest for its strong water absorption. The resulting image clearly showed that ICA effectively removed the water content in the detected signal allowing us to image the silica gel beads distinctively even though it was totally embedded in water before ICA was applied.
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We present measurements of sub-bandgap photoconductivity and photoconductive switches using GaAs doped heavily with Er such that nanoparticles of ErAs are formed. In addition to strong resonant absorption centered around 1550 nm, the material provides strong sub-bandgap photoconductivity and >> μW average power levels when fabricated into an efficient (square spiral) THz antenna and driven by a 1550- nm ultrafast fiber laser. Photo-Hall measurements prove that the predominant photocarrier is the electron and the linearity of the 1550-nm photocurrent (with laser power) suggests that the photoconductivity is “extrinsic”, not other possible mechanisms, such as two-photon absorption. These results have immediate relevance to the use of GaAs:Er switches as the transmitter in 1550-nm-driven THz imaging systems such as the “impulse imager” that we have successfully used for biomedical imaging applications.
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Novel THz Image Sensing Technologies and Applications II
Terahertz energy, with its ability to penetrate clothing and non-conductive materials, has held much promise in the area of security scanning. Millimeter wave systems (300 GHz and below) have been widely deployed. These systems have used full two-dimensional surface imaging, and have resulted in privacy concerns. Pulsed terahertz imaging, can detect the presence of unwanted objects without the need for two-dimensional photographic imaging. With high-speed waveform acquisition it is possible to create handheld tools that can be used to locate anomalies under clothing or headgear looking exclusively at either single point waveforms or cross-sectional images which do not pose a privacy concern. Identification of the anomaly to classify it as a potential threat or a benign object is also possible.
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We study and compare terahertz wave propagation in trapezoidal hollow-core aluminum waveguides with and without ridge with respect to attenuation and single-mode spectral bandwidth. Furthermore, we demonstrate a waveguide-based terahertz interferometer for terahertz sensing based on pure amplitude measurements without the necessity for a direct phase measurement.
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Milliwatt average power terahertz quantum cascade lasers (THz-QCLs) combined with microbolometer focal plane array cameras allow for acquisition rates on the order of 1×106 pixels/s. This system enables real-time imaging in transmission and reflection modes with signal to noise ratios of >25 dB per pixel. While these system allow rapid imaging for fairly transparent samples, signal to noise ratios of > 90 dB can be achieved with single element detectors where the samples are more opaque or require higher SNR. Systems using LongWave's terahertz QCLs and single/multi-element detectors will be presented.
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A foveated optical system has non-uniform resolution across its field of view. Typically, the resolution of such a lens is peaked in the center region of field of view, such as in the human eye. In biological systems this is often a result of localized depressions on the retina called foveae. Birds of prey, or raptors, have two foveae in each eye, each of which accounts for a localized region of high magnification within the raptor's field of view. This paper presents an analysis of the bifoveated vision of raptors and presents a method whereby this unique optical characteristic may be achieved in an optical system using freeform optics and aberration correction techniques.
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Numerical results are presented to show the characterization of an electromechanical actuator capable to achieve equally spaced phase shifts and fraction linear wavelength displacements aided by an interface and a computational system. Measurements were performed by extracting the phase with consecutive interference patterns obtained in a Michelson arrangement setup. This paper is based in the use of inexpensive resources on stability adverse conditions to achieve similar results to those obtained with high-grade systems.
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In the area of collecting field spectral data using a spectrometer, it is common to have the instrument over the material of interest. In certain instances it is beneficial to have the ability to remotely control the spectrometer. While several systems have the ability to use a form of connectivity to capture the measurement it is essential to have the ability to control the settings. Additionally, capturing reference information (metadata) about the setup, system configuration, collection, location, atmospheric conditions, and sample information is necessary for future analysis leading towards material discrimination and identification. This has the potential to lead to cumbersome field collection and a lack of necessary information for post processing and analysis. The method presented in this paper describes a capability to merge all parts of spectral collection from logging reference information to initial analysis as well as importing information into a web-hosted spectral database. This allows the simplification of collecting, processing, analyzing and storing field spectra for future analysis and comparisons. This concept is developed for field collection of thermal data using the Designs and Prototypes (D&P) Hand Portable FT-IR Spectrometer (Model 102). The remote control of the spectrometer is done with a customized Android application allowing the ability to capture reference information, process the collected data from radiance to emissivity using a temperature emissivity separation algorithm and store the data into a custom web-based service. The presented system of systems allows field collected spectra to be used for various applications by spectral analysts in the future.
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Previous work has used visible light scanning to detect and characterize defects in 3D printed objects. This paper focuses on assessing the internal structures and external surfaces (that will be later hidden) of complex objects. These features make in-process defect detection far more important than it would be with an object that can be fully assessed with a post-completion scan, as it is required both for in-process correction and end-product quality assurance. This paper presents work on the use of a multi-camera visible light 3D scanning system to identify defects with printed objects’ interior and covered / obscured exterior surfaces.
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Quality control is critical to manufacturing. Frequently, techniques are used to define object conformity bounds, based on historical quality data. This paper considers techniques for bespoke and small batch jobs that are not statistical model based. These techniques also serve jobs where 100% validation is needed due to the mission or safety critical nature of particular parts. One issue with this type of system is alignment discrepancies between the generated model and the physical part. This paper discusses and evaluates techniques for characterizing and correcting alignment issues between the projected and perceived data sets to prevent errors attributable to misalignment.
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Sensing applications along with free space data links can benefit from advanced laser sources that produce novel radiation patterns and tight spectral control for optical filtering. Vertical-cavity surface-emitting lasers (VCSELs) are being developed for these applications. While oxide VCSELs are being produced by most companies, a new type of oxide-free VCSEL is demonstrating many advantages in beam pattern, spectral control, and reliability. These lithographic VCSELs offer increased power density from a given aperture size, and enable dense integration of high efficiency and single mode elements that improve beam pattern. In this paper we present results for lithographic VCSELs and describes integration into military systems for very low cost pulsed applications, as well as continuouswave applications in novel sensing applications. The VCSELs are being developed for U.S. Army for soldier weapon engagement simulation training to improve beam pattern and spectral control. Wavelengths in the 904 nm to 990 nm ranges are being developed with the spectral control designed to eliminate unwanted water absorption bands from the data links. Multiple beams and radiation patterns based on highly compact packages are being investigated for improved target sensing and transmission fidelity in free space data links. These novel features based on the new VCSEL sources are also expected to find applications in 3-D imaging, proximity sensing and motion control, as well as single mode sensors such as atomic clocks and high speed data transmission.
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In this paper, a binary complementary metal oxide semiconductor (CMOS) image sensor with a gate/body-tied (GBT) metal oxide semiconductor field effect transistor (MOSFET)-type photodetector is presented. The sensitivity of the GBT MOSFET-type photodetector, which was fabricated using the standard CMOS 0.35-μm process, is higher than the sensitivity of the p-n junction photodiode, because the output signal of the photodetector is amplified by the MOSFET. A binary image sensor becomes more efficient when using this photodetector. Lower power consumptions and higher speeds of operation are possible, compared to the conventional image sensors using multi-bit analog to digital converters (ADCs). The frame rate of the proposed image sensor is over 2000 frames per second, which is higher than those of the conventional CMOS image sensors. The output signal of an active pixel sensor is applied to a comparator and compared with a reference level. The 1-bit output data of the binary process is determined by this level. To obtain a video signal, the 1-bit output data is stored in the memory and is read out by horizontal scanning. The proposed chip is composed of a GBT pixel array (144 × 100), binary-process circuit, vertical scanner, horizontal scanner, and readout circuit. The operation mode can be selected from between binary mode and multi-bit mode.
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Banpil Photonics has developed a novel high-performance multispectral photodetector array for Short-Wave Infrared (SWIR) imaging. The InGaAs based device uses a unique micro-nano pillar structure that eliminates surface reflection to significantly increase sensitivity and the absorption spectra compared to its macro-scaled thin film pixels counterpart (non-pillar). We discuss the device structure and highlight fabrication of the novel high performance multispectral image sensor. We also present performance results of the device characterization showing low dark current suitable for high performance imaging applications for the most demanding security, defense, and machine vision applications.
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Optical coherence tomography based on ultra technology is used for the assessment of subcutaneous tissue. Using high swept laser technology based on Fourier domain mode locking (FDML), the system operated in the 1300 nm wavelength range with axial scan rate of 150 kHz. Imaging at this wavelength range reduces optical scattering and improves imaging penetration depths in the tissues. The laser consists of a semiconductor amplifier as the gain medium, a tunable Fabry-Perot filter to change the wavelengthcand a long fiber ring cavity. The tuning range of laser is 102 nm. A balanced detector is used for spectra collection instead of the expensive CCD.
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This paper provides an overview of the capability of a 3D printer to successfully operate in-space to create structures and equipment useful in the field of scientific remote sensing. Applications of this printer involve oceanography, weather tracking, as well as space exploration sensing. The design for the 3D printer includes a parabolic array to collect and focus thermal energy. This thermal energy then be used to heat the extrusion head, allowing for the successful extrusion of the print material. Print material can range from plastics to metals, with the hope of being able to extrude aluminum for its low-mass structural integrity and its conductive properties. The printer will be able to print structures as well as electrical components. The current process of creating and launching a remote sensor into space is constrained by many factors such as gravity on earth, the forces of launch, the size of the launch vehicle, and the number of available launches. The design intent of the in-space 3D printer is to ease or eliminate these constraints, making space-based scientific remote sensors a more readily available resource.
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The relationship model of the sound signal and the coke state can be established through multiple test and comparison of the noise signal and the coke operation. By collecting data, we summarize the main frequency power fluctuation range of the sound signal in kinds of state, and extract the nearest 5 decision results for reference. The weighted value of each result according to the update time has gradually increased. On the basis of that, we developed visualization software, real-time reflect out coke coking tower state. Animation refresh rate is second level, and the vertical height can be accurate to 0.1m.
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Epi-ready GaSb wafers with low absorption coefficients are of a special interest as substrates for molecular beam epitaxy (MBE) growth of material for IR focal plane arrays that operate under back-side illumination configuration, when the substrate is not completely removed. While low absorption coefficient across a broad IR spectral range (~2um-20um) is achievable in GaSb crystals with low Te doping, the control of the doping distribution across the wafers is especially challenging in the mass-production of optically transparent, high-resistivity Te-doped GaSb wafers. In this work, we examine data from the n-type and p-type Te-doped GaSb samples with doping concentration below 1e18 cm-3. The carrier concentration measured by the Hall and the transmission data measured by FTIR spectroscopy are correlated. We perform a rigorous analysis of the absorption coefficient based on the free-carrier absorption mechanism that is dominant for the n-type GaSb and the inter-valence band absorption due to the transitions from the light-hole to the heavy-hole band that is the dominant absorption mechanism for the p-type GaSb. Based on the correlation between the Hall and the FTIR data, carrier concentration profile can be estimated from the non-destructive FTIR transmission mapping of the wafer.
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Against the backdrop of a growing demand in the areas of smart buildings, security, vehicle installation, and other applications, the market for far infrared cameras is expected to grow significantly in the future. However, since germanium (Ge) and chalcogenide glass, which have been used as the lens materials of far infrared cameras, are very expensive or highly toxic, there are some problems supporting the growing demand. We have therefore focused attention on silicon, which is inexpensive and less toxic. Although silicon has been used as a lens material of far infrared cameras, there are some problems remaining to be solved: Cz silicon is inexpensive but delivers low transmittance, and Fz silicon delivers sufficient transmittance but is expensive. We have developed New Cz silicon, which delivers high transmittance as Fz silicon does, and is inexpensive as conventional Cz silicon is. We have already started its sample work at both companies in Japan and overseas and have obtained excellent performance results. Mass production is scheduled to start in this fiscal year.
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