We present design concepts for calibrated hyperspectral image projectors (HIP) and related sources intended for system-level testing of instruments ranging from complex hyperspectral or multispectral imagers to simple filter radiometers. HIP, based on the same digital mirror arrays used in commercial digital light processing (DLP) displays, is capable of projecting any combination of many different arbitrarily programmable basis spectra into each pixel of the unit under test (UUT) at video frame rates. The resulting spectral and spatial content of the image entering the UUT can simulate, at typical video frame rates and integration times, realistic scenes to which the UUT will be exposed during use. Also, its spectral radiance can be measured with a calibrated spectroradiometer, such that the hyperspectral photon field entering the UUT is well known. Use of such generated scenes in a controlled laboratory setting would alleviate expensive field testing, allow better separation of environmental effects from instrument effects, and enable system-level performance testing and validation. Example potential applications include system-level testing of complex hyperspectral imaging instruments as implemented with data reduction algorithms when viewing realistic scenes, testing the performance of simple fighter-fighter infrared cameras under simulated adverse conditions, and hardware-in-the-loop testing of multispectral and hyperspectral systems.

In this study, three different detectors, regular InGaAs, short-wave infrared extended-InGaAs (exInGaAs) with the bandgap wavelength at 2.6 μm and short-wave HgCdTe (swMCT) with the bandgap wavelength at 2.8 μm are studied. The detectors have active areas of 3 mm or 1 mm diameter with all the detectors capable of being cooled from room temperatures to -85 °C with 4-stage thermo-electric coolers. Two of the detectors have field-of-view limiting, cold shrouds attached. From room temperatures to their coldest operating temperatures, the detectors are compared for their temperature-dependent shunt resistances, absolute spectral power responsivities, and noise performances at the output of the photocurrent meter. The photodiode current measuring circuit is analyzed to determine the effect of the shunt resistance for the output offset voltage, the noise and drift amplification, the uncertainty of the current-to-voltage conversion, and the linear operation. The temperature dependences of the shunt resistances are described by Arrhenius plots, and the spectral power responsivities are determined against a pyroelectric detector standard with constant responsivity versus wavelength. We determine that the shunt resistances of regular InGaAs photodiodes can increase to 5 GΩ when cooled to -20 °C demonstrating Si-like performance. The shunt resistances of the 1 mm diameter extended InGaAs and short-wave MCT photodiodes were both measured to be about 11 MΩ at diode temperatures of -70 °C. Further increase in the shunt resistances would be possible with decreasing diode temperatures. The noise voltage at the output of the photocurrent-to-voltage converter is measured for the respective detectors to determine the noise-equivalent power.

A cryogenic Fourier transform infrared spectrometer (Cryo-FTS) was developed for the Low Background Infrared (LBIR) facility at the National Institute of Standards and Technology (NIST). This spectrometer was developed for the Missile Defense Agency Transfer Radiometer (MDXR) that will be used to calibrate infrared sources that can not be transported to NIST for calibration. When used inside the MDXR, the Cryo-FTS is expected to be able to provide relative spectral measurements with an accuracy of < 0.3 % uncertainty of infrared sources with a spectral range from 4 μm to 15 μm and a spectral resolution of 0.6 cm^-1. The Cryo-FTS spectral range is determined by the beamsplitter since all of its other optics use reflective materials. The compact interferometer uses a compensated Michelson configuration and has an operating temperature range between 10 K and 340 K with very low static beam redirection (< 215 μrad). The interferometer uses flat metal mirrors and KBr flat optics and maintains low wavefront distortion for infrared beams of up to 1.63 cm diameter. It integrates a digitally servo-controlled porchswing mechanism to provide an accurate and repeatable optical path difference and is supported by a Wavefront Alignment (WA) system to correct for wavefront residual tilt in real time using a fibre optic based metrology system. The interferometer is expected to provide modulation efficiency of better than 22% with limited power dissipation (< 2.8 W) during continuous operation.

The development of quantum well infrared photodetector (QWIP) technologies for thermal imaging is well known. The high frequency and high speed capability is less known. Here we report on our recent advances of reaching over 100 GHz in heterodyne detection both at cryogenic and room temperatures. These advances may lead to new applications. One of such examples is free space optical communication.

Multicolor detectors have a strong potential to replace conventional single-color detectors in application dealing with the simultaneous detection of more than one wavelength. This will lead to the reduction of heavy and complex optical components now required for spectral discrimination for multi-wavelengths applications. This multicolor technology is simpler, lighter, compact and cheaper with respect to the single-color ones. In this paper, Sb-based two-color detectors fabrication and characterization are presented. The color separation is achieved by fabricating dual band pn junction on a GaSb substrate. The first band consists of an InGaAsSb pn junction for long wavelength detection, while the second band consists of a GaSb pn junction for shorter wavelength detection. Three metal contacts were deposited to access the individual junctions. Surface morphology of multi-layer thin films and also device characteristics of quasi-dual band photodetector were characterized using standard optical microscope and electro-optic techniques respectively. Dark current measurements illustrated the diode behavior of both lattice-matched detector bands. Spectral response measurements indicated either independent operation of both detectors simultaneously, or selective operation of one detector, by the polarity of the bias voltage, while serially accessing both devices.

This model was developed in matlab with I/O links to excel spreadsheets to add realistic and accurate sensor effects to scene generator or actual sensor/camera images. The model imports scene generator or sensor images, converts these radiance images into electron maps and digital count maps, and modifies these images in accordance with user-defined sensor characteristics such as the response map, the detector dark current map, defective pixel maps, and 3-D noise (temporal and spatial noise). The model provides realistic line-of-sight motion and accurate and dynamic PSF blurring of the images. The sensor model allows for the import of raw nonuniformities in dark current and photoresponse, performs a user-defined two-point nonuniformity correction to calculate gain and offset terms and applies these terms to subsequent scene images. Some of the model's capabilities include the ability to fluctuate or ramp FPA and optics temperatures, or modify the PSF on a frame-by-frame basis. The model also functions as an FPA/sensor performance predictor and an FPA data analysis tool as FPA data frames can be input into the 3-D noise evaluation section of the model. The model was developed to produce realistic infrared images for IR sensors.

Doping of the lead telluride and related alloys with the group III impurities results in appearance of unique physical features of a material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident photon), radiation hardness and many others. As a result, single photodetectors based on Pb_1-xSn_xTe(In) demonstrate extremely high performance in the Terahertz wavelength range. Furthermore, it is shown that local long-lived non-equilibrium states are generated in Pb_1-xSn_xTe(In) alloys at low temperatures under the action of local Terahertz excitation. This result opens a possibility for construction of a "continuous" focal-plane array for detection of Terahertz radiation. Ideas for readout of information from this array are discussed.

Quantum dot infrared photodetectors (QDIPs) have recently emerged as promising candidates for detection in the middle wavelength infrared (MWIR) and long wavelength infrared (LWIR) ranges. This is due to the QDIPs' absorption of normally incident light, potential room-temperature operation and high responsivity. These unique features are a direct consequence of the three-dimensional confinement potential achieved in quantum dots that provides a discrete density of states and a longer life time of excited electrons due to the "phonon bottleneck" effect. Here, we report our recent results for mid-wavelength QDIPs grown by low-pressure metalorganic chemical vapor deposition. The device structure was gown on a semi-insulating GaAs (001) substrate. The active region consisted of ten In_0.68Ga_0.32As quantum dot layers separated by 35nm-thick In_0.49Ga0.₅₁P barriers. Three monolayer of In_0.68Ga_0.32As self-assembled via the Stranski-Krastanov growth mode and formed lens-shaped InGaAs quantum dots with a density around 3×10¹⁰cm^-2. The peak responsivity at 77 K was measured to be 3.4 A/W at a bias of -1.9 V with 4.7 μm peak detection wavelength. A high peak detectivity of 3×10¹² cmHz^1/2/W was achieved at 77 K and a bias of -1.9 V. The temperature dependent device performance was also investigated. The improved temperature insensitivity compared to quantum well infrared photodetectors (QWIPs) was attributed to the quantum dots properties. The device showed a background limited performance temperature of 220 K with a 45° field of view and 300K background. Focal plane arrays (FPAs) based on these devices have been developed. The preliminary result of FPA imaging is presented.

The Atmospheric Chemistry Experiment (ACE) is the mission on-board Canadian Space Agency's science satellite, SCISAT-1. ACE consists of a suite of instruments in which the primary element is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2-channel visible (525 nm) and near infrared imager (1020 nm). A secondary instrument, MAESTRO, provides spectrographic data from the near ultra-violet to the near infrared, including the visible spectral range. In combination, the instrument payload covers the spectral range from 0.25 to 13.3 micron. A comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols and temperature are being made by solar occultation from this satellite in low earth orbit. The ACE mission measures and analyses the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere. A high inclination (74°), low earth orbit (650 km) allows coverage of tropical, mid-latitude and polar regions. The ACE/SciSat-1 spacecraft was launched by NASA on August 12^th, 2003. This paper presents the status of the ACE-FTS instrument, after three years on-orbit. On-orbit performances as well as their optimization are presented. Needs for future missions similar to ACE are discussed.

Access to an internal calibration reference system during flight is an important requirement for contemporary remote sensing missions. L-3 Communications SSG-Tinsley has designed, built, and tested a novel internal calibration source based on ribbon sources. Via a flip-in mirror, the source assembly couples light through the field stop of an off-axis reimaging telescope to provide a reliable test of the following optics and electronics. Non-imaging illumination design principles assure uniform illumination of the sensor focal plane at levels adjustable over a very wide dynamic range. The source assembly can be packaged into a compact, lightweight, and efficient flight unit for convenient installation at an accessible location on the telescope. While the prototype source was specifically designed to match the GIFTS telescope as a representative example of an off-axis re-imaging telescope, the design principles are flexible to allow optimization for any comparable telescope system.

The Solar Occultation For Ice Experiment (SOFIE) is scheduled for launch onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite in March 2007. SOFIE is designed to measure polar mesospheric clouds (PMCs) and the environment in which they form. SOFIE will conduct solar occultation measurements in 16 spectral bands that are used to retrieve vertical profiles of temperature, O₃, H₂O, CO₂, CH₄, NO, and PMC extinction at 10 wavelengths. Thirty occultations are observed each day covering latitudes from 65° - 85°S and 65° - 85°N. The PMC measurements are simultaneous with temperature and gas measurements that are unaffected by PMC signal. This data set will be the first of its kind, and allow new advancements in the understanding of the upper mesosphere.

Space Dynamics Laboratory (SDL) recently designed, built, and delivered the Solar Occultation for Ice Experiment (SOFIE) instrument as the primary sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM) instrument suite. AIM's mission is to study polar mesospheric clouds (PMCs). SOFIE will make measurements in 16 separate spectral bands, arranged in eight pairs between 0.29 and 5.3 μm. Each band pair will provide differential absorption limb-path transmission profiles for an atmospheric component of interest, by observing the sun through the limb of the atmsophere during solar occulation as AIM orbits Earth. A pointing mirror and imaging sun sensor coaligned with the detectors are used to track the sun during occulation events and maintain stable alignment of the sun on the detectors. This paper outlines the mission requirements and goals, gives an overview of the instrument design, fabrication, testing and calibration results, and discusses lessons learned in the process.

The SOFIE pointing control system (PCS) locates and tracks the top edge of the sun and periodically scans the solar disk for calibration. Primary hardware components are a steering mirror assembly (SMA), sun sensor, vibration isolation system (VIS), and associated electronics. The SMA has a 100-Hz control bandwidth and is capable of ±1.6 mechanical degree deflection in azimuth and elevation axes. The sun sensor uses a 1024x1024 pixel, radiation-hardened focal plane array and coarse and fine tracking algorithms to report the solar centroid and edge positions to the PCS. The PCS control law uses this information to command the SMA. A change in launch loads necessitated the development of the VIS, which features passive viscoelastic damping to protect the SMA. A rapid prototyping methodology was used to develop the control laws for the inner SMA feedback loop and outer PCS feedback loop. The methodology features integrated end-to-end modeling of structural dynamics, controls, and optics; automatic C-code synthesis from block diagrams; real-time hardware-in-the-loop (HIL) testing; and the ability to change control parameters "on the fly." Extensive testing of the PCS shows stable pointing performance of about 2 arcsec in the presence of 60-arcsec disturbances, compared to the requirement of 15 arcsec.

Space Dynamics Laboratory (SDL), in partnership with GATS, Inc., designed and built an instrument to conduct the Solar Occultation for Ice Experiment (SOFIE). SOFIE is the primary infrared sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM) instrument suite. AIM's mission is to study polar mesospheric clouds (PMCs). SOFIE will make measurements in 16 separate spectral bands, arranged in eight pairs between 0.29 and 5.3 μm. Each band pair will provide differential absorption limb-path transmission profiles for an atmospheric component of interest, by observing the sun through the limb of the atmosphere during solar occultation as AIM orbits Earth. A pointing mirror and imaging sun sensor coaligned with the detectors are used to track the sun during occultation events and maintain stable alignment of the sun on the detectors. Ground calibration experiments were performed to measure SOFIE end-to-end relative spectral response, nonlinearity, and spatial characteristics. SDL's multifunction infrared calibrator #1 (MIC1) was used to present sources to the instrument for calibration. Relative spectral response (RSR) measurements were performed using a step-scan Fourier transform spectrometer (FTS). Out-of-band RSR was measured to approximately 0.01% of in-band peak response using the cascaded filter Fourier transform spectrometer (CFFTS) method. Linearity calibration was performed using a calcium fluoride attenuator in combination with a 3000K blackbody. Spatial characterization was accomplished using a point source and the MIC1 pointing mirror. SOFIE sun sensor tracking algorithms were verified using a heliostat and relay mirrors to observe the sun from the ground. These techniques are described in detail, and resulting SOFIE performance parameters are presented.

The Greenhouse gases Observing SATellite (GOSAT) is a satellite to monitor the carbon dioxide (CO₂) and the methane (CH₄) globally from orbit. GOSAT will be placed in a 666 km sun-synchronous orbit of 13:00 local time, with an inclination angle of 98 deg. Two instruments are accommodated on GOSAT. Thermal And Near infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) detects the Short wave infrared (SWIR) reflected on the earth's surface as well as the thermal infrared (TIR) radiated from the ground and the atmosphere. TANSO-FTS is capable of detecting wide spectral coverage, specifically, three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm^-1 spectral resolution. TANSO Cloud and Aerosol Imager (TANSO-CAI) is a radiometer of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The paper presents the instrument design of TANSO-FTS/CAI, and test results using Bread Board Model (BBM) are presented.

The Greenhouse gases Observing SATellite (GOSAT) is designed to monitor the global distribution of carbon dioxide (CO₂) from orbit. It is a joint project of Japan Aerospace Exploration Agency, the Ministry of Environment (MOE), and the National Institute for Environmental Studies (NIES). JAXA is responsible for the satellite and instrument development, MOE is involved in the instrument development, and NIES is responsible for the satellite data retrieval. It is scheduled to be launched in 2008. As existing ground monitoring stations are limited and still unevenly distributed, the satellite observation has advantages of global and frequent observations. The objective of the mission is in response to COP3 (Kyoto Protocol): Observation of Green House Gases (GHGs) including CO₂ with 1% relative accuracy in sub-continental spatial resolution and to identify the GHGs source and sink from the data obtained by GOSAT in conjunction with the data from the ground instruments, with simulated models. In order to detect the CO₂ variation of boundary layers, the technique to measure the column density and the retrieval algorithm to remove cloud and aerosol contamination are investigated. The simultaneous observation of methane (CH₄), which is the second largest contribution molecule, is studied. A Thermal And Near infrared Sensor for carbon Observation (TANSO) based on a Fourier transform spectrometer (FTS) with high optical throughput and spectral resolution is currently under design for the GOSAT mission. This paper presents an overview of the design of the TANSO interferometer as well as key reliability enhancement activities conducted during the design phase.

The performance of modern IR instruments is becoming so good that meeting science requirements requires an accurate instrument model be used throughout the design and development process. The huge cost overruns on recent major programs are indicative that the design and cost models being used to predict performance have lagged behind anticipated performance. Tuning these models to accurately reflect the true performance of target instruments requires a modeling process that has been developed over several instruments and validated by careful calibration. The process of developing a series of Engineering Development Models is often used on longer duration programs to achieve this end. The accuracy of the models and their components has to be validated by a carefully planned calibration process, preferably considered in the instrument design. However, a good model does not satisfy all the requirements to bring acquisition programs under control. Careful detail in the specification process and a similar, validated model on the government side will also be required. This paper discusses the model development process and calibration approaches used to verify and update the models of several new instruments, including Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and Far Infrared Spectroscopy of the Troposphere (FIRST).

Space Dynamics Laboratory (SDL), in partnership with GATS, Inc., designed, built, and calibrated an instrument to conduct the Solar Occultation for Ice Experiment (SOFIE). SOFIE is the primary infrared sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM) instrument suite. AIM's mission is to study polar mesospheric clouds (PMCs). SOFIE will make measurements in 16 separate spectral bands, arranged in 8 pairs between 0.29 and 5.3 μm. Each band pair will provide differential absorption limb-path transmission profiles for an atmospheric component of interest, by observing the sun through the limb of the atmosphere during solar occultation as AIM orbits Earth. A fast steering mirror and imaging sun sensor coaligned with the detectors will track the sun during occultation events and maintain stable alignment of the Sun on the detectors. This paper outlines the instrument specifications and resulting design. The success of the design process followed at SDL is illustrated by comparison of instrument model calculations to calibration results, and lessons learned during the SOFIE program are discussed. Relative spectral response predictions based on component measurements are compared to end-to-end spectral response measurements. Field-of-view measurements are compared to design expectations, and radiometric predictions are compared to results from blackbody and solar measurements. Measurements of SOFIE detector response non-linearity are presented, and compared to expectations based on simple detector models.

The radiative balance of the troposphere, and hence global climate, is dominated by the infrared absorption and emission of water vapor, particularly at far-infrared (far-IR) wavelengths from 15-50 μm. Current and planned satellites observe the infrared region to about 15.4 μm, ignoring spectral measurement of the far-IR region from 15 to 100μm. The far-infrared spectroscopy of the troposphere (FIRST) project, flown in June 2005, provided a balloon-based demonstration of the two key technologies required for a space-based far-IR spectral sensor. We discuss the FIRST Fourier transform spectrometer system (0.6 cm^-1 unapodized resolution), its radiometric calibration in the spectral range from 10 to 100 μm, and its performance and science data from the flight. Two primary and two secondary goals are given and data presented to show the goals were achieved by the FIRST flight.

The Wide Field Infrared Survey Explorer is a NASA Medium Class Explorer mission to perform an all-sky survey in four infrared wavelength bands. The science payload is a cryogenically cooled infrared telescope with four 1024² infrared focal plane arrays covering from 2.8 to 26 μm. Advances in focal plane technology and a large aperture cryogenic telescope allow an all-sky survey to be performed with high sensitivity and resolution. An efficient survey is obtained using a cryogenic scan mirror to freeze the field of view on the sky over the 9.9-second frame integration time. Mercury cadmium telluride (MCT) detectors, cooled to 32 K, are used for the two midwave channels (3.3 μm and 4.6 μm), and Si:As detectors, cooled to < 8.3 K, are used for the two long wavelength channels (12 μm and 23 μm). Cooling is provided by a two-stage solid hydrogen cryostat which provides temperatures < 17 K and < 8.3 K at the telescope and Si:As focal planes, respectively. The science payload supports operations on orbit for the seven-month baseline mission with a goal to support a 13-month extended mission, if possible. The payload recently passed CDR and is being fabricated. This paper provides a payload overview and discusses instrument requirements and performance.

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) was developed for the NASA New Millennium Program (NMP) Earth Observing-3 (EO-3) mission. This paper discusses the GIFTS measurement requirements and the technology utilized by the GIFTS sensor to provide the required system performance. Also presented are preliminary results from the recently completed calibration of the instrument. The GIFTS NMP mission challenge was to demonstrate new and emerging sensor and data processing technologies to make revolutionary improvements in meteorological observational capability and forecasting accuracy using atmospheric imaging and hyperspectral sounding methods. The GIFTS sensor is an imaging FTS with programmable spectral resolution and spatial scene selection, allowing radiometric accuracy and atmospheric sounding precision to be traded in near-real time for area coverage. System sensitivity is achieved through the use of a cryogenic Michelson interferometer and two large-area, IR focal plane detector arrays. Due to funding limitations, the GIFTS sensor module was completed as an engineering demonstration unit, which can be upgraded for flight qualification. Capability to meet the next generation geosynchronous sounding requirements has been successfully demonstrated through thermal vacuum testing and rigorous IR calibration activities.

The NASA Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) has been completed as an Engineering Demonstration Unit (EDU) and has recently finished thermal vacuum testing and calibration. The GIFTS EDU was designed to demonstrate new and emerging sensor and data processing technologies with the goal of making revolutionary improvements in meteorological observational capability and forecasting accuracy. The GIFTS EDU includes a cooled (150 K), imaging FTS designed to provide the radiometric accuracy and atmospheric sounding precision required to meet the next generation GOES sounder requirements. This paper discusses a GIFTS sensor response model and its validation during thermal vacuum testing and calibration. The GIFTS sensor response model presented here is a component-based simulation written in IDL with the model component characteristics updated as actual hardware has become available. We discuss our calibration approach, calibration hardware used, and preliminary system performance, including NESR, spectral radiance responsivity, and instrument line shape. A comparison of the model predictions and hardware performance provides useful insight into the fidelity of the design approach.

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, a 10-channel infrared (1.27 - 16.9 μm) radiometer, was launched on the TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) satellite in December 2001 from Vandenburg Air Force Base. SABER is being used to measure earthlimb emissions and to characterize infrared radiation, allowing calculation of cooling rates and determination of composition and temperature profiles in the mesosphere, lower thermosphere, and ionosphere (60-180 km). The SABER telescope is an on-axis Cassegrain design with a picket-fence tuning fork chopper at the first focus and a clamshell re-imager to focus the image on the focal plane. The telescope was designed to reject stray light from the Earth and atmosphere outside the instrument's instantaneous field-of-view (IFOV). The baffle assembly contains a single-axis scan mirror, which permits the 2 km vertical IFOV of each detector to be scanned from the Earth to a 400 km tangent height. The telescope and baffle assembly are cooled to 220 K by a dedicated radiator. The focal plane assembly is cooled to 75 K by a miniature cryogenic refrigerator. Field programmable gate arrays are used to implement state machine algorithms for control and operation of the instrument and subsystems. Although originally designed for a two-year lifetime requirement, the SABER instrument has been in continuous operation since January 2002. This paper discusses the SABER instrument design and innovations developed to achieve the required performance, along with instrument performance and lessons learned from the program.

The sounding of the atmosphere using broadband emission radiometry (SABER) instrument is a 10-channel infrared (1.27-16.9μm) radiometer launched on the TIMED (Thermosphere, Ionosphere, Mesosphere Energetics, and Dynamics) satellite in December 2001 from Vandenburg Air Force Base. SABER measures earthlimb emissions and characterizes infrared radiation, allowing calculation of atmospheric temperature and composition (ozone, water vapor, and carbon dioxide), as well as solar and chemical heating rates and infrared cooling rates. Although SABER focuses on the unexplored 60-180km region, it makes measurements covering the 10-350km altitude region. Ground calibration testing was completed in September 1999. Subsequent data analyses and report generation were completed in June, 2000. This paper provides a brief overview of instrument design, calibration planning, ground calibration testing, and results. Also included is an assessment of nearly five years of post launch validation and calibration maintenance. Using SABER as an example, conclusions are given regarding the benefit of a detailed calibration approach and how it enhances the quality of science data and mission success.

The term "Smart Sensors" refer to sensors which contain both sensing and signal processing capabilities with objectives ranging from simple viewing to sophisticated remote sensing, surveillance, search/track, weapon guidance, robotics, perceptronics and intelligence applications. In a broad sense, they include any sensor systems covering the whole electromagnetic spectrum: this paper deals specifically with a new class of smart sensors in infrared spectral bands whose developments started some years ago, when it was recognized that the rapid advances of "very large scale integration" (VLSI) processor technology and mosaic infrared detector array technology could be combined to develop new generations of infrared smart sensor systems with much improved performance. So, sophisticated signal processing operations have been developed for these new systems by integrating microcomputers and other VLSI signal processors within or next to the sensor arrays on the same focal plane avoiding complex computing located far away from the sensors. Recently this approach is achieving higher goals by a new and revolutionary sensors concept which introduce inside the sensor some of the basic function of living eyes, such as dynamic stare, dishomogenity compensation, spatial and temporal filtering. New objectives and requirements of these new focal plane processors are presented for this type of new infrared smart sensor systems. This paper is concerned with the processing techniques for only the front end of the focal plane processing, namely, the enhancement of target-to-noise ratio by background clutter suppression and the improvement in target detection by "smart" and pattern correlation threshold.

With a background of several instrument developments in the past the German Aerospace Center in Berlin proposed for ESA's deep space mission BepiColombo an imaging spectrometer which meets the challenges of limited technical resources and a very special operational environment. An 80-channel push broom-type spectrometer has been drafted and it s development has been started under the name MERTIS (MErcury Radiometer and Thermal Infrared Spectrometer). The instrument is dedicated to the mineralogy surface science and thermal characteristics studies of the innermost planet. It is based on modern un-cooled micro-bolometer technology and all-reflective optics design. The operation concept principle is characterised by intermediate scanning of the planet, deep space and black bodies as calibration targets. A miniaturised radiometer is included for low level temperature measurements. Altogether the system shall fit into a CD-package sized cube and weigh less than 3 kg. The paper will present the instrument architecture of MERTIS, its design status and will show the results of first components being built.

As a part of the ESA deep space mission to mercury - BepiColombo - investigations of mercury's surface layer using a push-broom thermal infrared imaging spectrometer (MERTIS) with a high spectral resolution is planned. One of the scientific goals is the measurement of Christiansen Features which are emissivity maxima resulting from rapid changes in the real part of the mineral's refractive index. Their positions within the spectral range of 7-14μm deliver information about mineralogical compositions. For these measurement MERTIS needs to have a high spectral resolution of 90nm. The planet will be mapped with a resolution of 500m and a S/N ratio of at least 100. For the measurement of the surface radiation a micro-bolometer detector array will be used. A detectivity of 1.0E9 is required. High sensitive TIR systems commonly use cooled detectors with a large mass budget and high electrical power consumption. One of the challenges of MERTIS is the use of an uncooled micro-bolometer detector. The development of MERTIS is currently in an early phase but a breadboard concept will be presented. Special attention is payed to the first of two phases of the breadboard concept: The Radiometric Breadboard (RAB) has been configured for the development of the opto-electronical components and for the investigation of radiometric calibration methods and algorithms. The design of the RAB is already a spectrometer configuration but it cannot reach the performance the technical and scientific requirements demand. The Spectro-Radiometric Breadboard (SRB) will be implemented for investigations of the performances of the optics and detector of MERTIS. Relevant components have to be developed and validated particularly in the spectral domain. The SRB will be the prototype of MERTIS.

The identification of buried archaeological structures, using remote sensing technologies (aerophotos or satellite and airborne images) is based on the analysis of surface spectral features changes that overlying underground terrain units, located on the basis of texture variations, humidity and vegetation cover. The study of these anomalies on MIVIS (Multispectral Infrared and Visible Imaging Spectrometer) hyperspectral data is the main goal of a research project that the CNR-IIA has carried on over different archaeological test sites. The major archaeological information were gathered by data analysis in the VIS and NIR spectral region and by use of the apparent thermal inertia image and their different vegetation index.

The demands of modern radiation thermometry and radiometry are being satisfied by a large variety of high-precision unique BB sources (both fixed-point and variable temperature) designed for a wide range of temperature from 100 K to 3500 K. The paper contains a detailed review of low-, medium- and high-temperature precision blackbodies developed at VNIIOFI as the basis of the spectral radiance and irradiance calibration devices in the rank of National standards. The blackbodies include: 1) variable-temperature (100K..1000K) research-grade extended-area (up to 100 mm) models intended to perform radiometric calibrations by comparison with a primary standard source, as well as can be used as the sources for high-accuracy IR calibration of space-borne and other systems not requiring a vacuum environment; 2) low-temperature fixed-point blackbodies on the basis of phase transitions of pure metals such as In and Ga sources, and the metal-metal eutectics operating within the medium-temperature range (300K to 400K); these are used for pyrometric measurements, IR-radiometry, preflight and (future aspects) in-flight calibration of space borne IR instruments; 3) high-temperature wide aperture variable-temperature blackbodies (1800K to 3500K) such as BB3500MP, BB3500YY designed and fabricated, along with fixed-point cells working above the ITS-90 temperatures on the basis of phase transitions of metal-carbon eutectic alloys (Re-C, TiC-C, ZrC-C, HfC-C), which possess unique reproducibility of 0.1% or less.

The full potential of far infrared and submillimeter detectors, operating at deep cryogenic temperatures (<4.2K), is only realized if large, two-dimensional arrays of these detectors are developed. The technology for fabricating suitable readouts for such detectors has been one of the main impediments in achieving this objective. In this paper, we present the design parameters of the first 2-side buttable, 32x32 (64x64 mosaic) readout multiplexer, specifically designed for direct-hybrid far IR detector arrays. The readout employs a high open-loop gain, capacitive transimpedance unit-cell design with eight outputs. It features eight selectable gain settings, AC coupling (auto zero) for better input uniformity, sample-and-hold circuitry, and provision to limit the readout glow. A special, 2-micron cryo-CMOS process has been adopted to prevent freeze out and ensure low noise and proper operation at deep cryogenic temperatures. Based on the performance of its predecessors, CRC696 and SBRC190, this device is expected to have CDS read noise of better than 100e^- at 2K.

We describe the experimental setup to determine temperature distribution of an optical fiber with an object-space resolution of less than 0.01 μm. Determination of temperature distribution with the spatial resolution of about 7 μm as a function of position and time is reported here for the first time, to the best of our knowledge. We applied the highresolution measurements to confirm the feasibility of using the rare-earth-doped silica as an IR-to-visible converter.

Both absolute and differential temperature measurements were simultaneously performed as a function of time for a pixel on a high-temperature, multi-spectral, spatially and temporally varying infrared target simulator. A scanning laser beam was used to maintain a pixel at an on-the-average constant temperature of 520 K. The laser refresh rate of up to 1 kHz resulted in small-amplitude temperature fluctuations with the peak-to-peak amplitude of less than 1 K. The experimental setup to measure accurately the differential and the absolute temperature as a function of time is described.