The Wide-field Infrared Survey Explorer (WISE) is a medium class NASA Explorer mission designed to map the entire sky in 4 mid-infrared bands, with band centers at 3.4, 4.6, 12 & 22 μm. The sensitivity requirements are 120, 160, 850 & 4000 μJy in these bands. The angular resolution should be 6" FWHMor better except at 22 μm where diffraction in the 40 cm diameter aperture degrades the resolution to 12" FWHM. WISE takes images simultaneously in all 4 bands in a 47' FOV using 1024² pixel arrays and 2.75" pixels. WISE will be launched into a 500 km altitude 97° inclination Sun-synchronous orbit at the terminator. Launch is currently scheduled for 6 AM in late 2009. WISE scans a circle perpendicular to the Earth-Sun line which leads to an all-sky survey in 6 months.

Carbon nanotube (CNT) has been found to be one of the promising materials for efficient detection and used in different nanoelectronic devices due to its unique electrical properties. Recently, the applications of nanostructural material to infrared (IR) sensors are considered. Our group has developed non cryogenic cool and multiple spectrums optical sensors using single CNT and demonstrated the good sensitivity of CNT to the infrared light in different ranges. In this paper, design, fabrication and experimental result of the CNT-based optical sensor were described. The results indicated the band gap of CNTs can be tuned by electrical breakdown process, resulting multiple spectrum sensors can be developed by controlling the band gap of CNTs. Moreover, the CNT-based optical sensor detected the near-IR (NIR) signal and middle-wave IR (MWIR) signal in room temperature environment, the temperature dependency of the sensors has been studied.

Pyroelectric infrared Lithium tantalite [(LiTaO₃), LT] ceramic particles and silver nanoparticles have been incorporated into a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70/30 mol%] copolymer matrix to form composite films. The films were prepared using solvent casting method. Electrical properties such as the dielectric constant, dielectric loss, and pyroelectric coefficient have been measured as a function of temperature. In addition, materials' figures-of-merit have also been calculated to assess their use in infrared detectors. The results show that the fabricated silver nanoparticles incorporated lithium tantalite: polyvinylidene fluoride-trifluoroethylene composite films may have a good potential for uncooled infrared sensor applications.

In this paper, we report that integrated pyroelectric infrared(IR) sensor array using surface micromachine technique with nMOS/nJFET devices on epitaxial γ-Al₂O₃/Si substrates has been successfully fabricated. Orientation and crystallinity control of pyroelectric and ferroelectric films are important to archive high sensitivity pyroelectric IR detector. We propose epitaxial γ-Al₂O₃ thin films as buffer layer on Si substrates to control them. Each pixel of fabricated IR sensor array has a thermally isolated Au/PZT(001)/Pt(001)/γ-Al₂O₃ stacked membrane detector, a low noise nJFET source follower and a switching nMOSFET. A voltage sensitivity of a fabricated detector is increased by forming thermal isolated structure. The fabricated sensor operated under a chopping frequency of 100 Hz. The R_V, NEP and D* at 30 Hz are 1703 V/W, 7.22 × 10^-11 WHz^-1/2 and 1.38 × 108 cmHz1/2W^-1, respectively. This sensor will have potential for Si integrated pyroelectric IR imager.

A new pyroelectric polar nanocomposite thin film is presented. A dense array of aluminium oxide cylindrical nanopores is used as a template to grow pyroelectric nano-crystals of TriGlycine Sulfate (TGS). The crystals are grown inside nanopores having an average diameter of 14±4nm and a length of 0.5 micron. The crystals are grown with a preferred crystallographic orientation having their polar axis [010] aligned in vertical to the film plane. The pyroelectric response at different temperatures is measured using the dynamic method. The dielectric characterization reveals resistivity of about 1E-9 ohm-m, dielectric loss (tan(δ)) of about 0.03, and relative dielectric permittivity of about 10 at room temperature which increases to a maximum value at the ferroelectric-paraelectric phase transition. The pyroelectric coefficient of the film is about 3.5 μC/m²K and the pyroelectric voltage figure of merit is about 40 kVm^-1K ^-1.

The James Webb Space Telescope, an infrared-optimized space telescope being developed by NASA for launch in 2014, will utilize cutting-edge detector technology in its investigation of fundamental questions in astrophysics. JWST's near infrared spectrograph, NIRSpec utilizes two 2048 × 2048 HdCdTe arrays with Sidecar ASIC readout electronics developed by Teledyne to provide spectral coverage from 0.6 microns to 5 microns. We present recent test and calibration results for the "pathfinder NIRSpec detector subsystem" as well as data processing routines for noise reduction and cosmic ray rejection.

A long wave infrared (LWIR) division of amplitude imaging Stokes polarimeter is presented. For the first time, to our knowledge, application of microbolometer focal plane array (FPA) technology to polarimetry is demonstrated. The sensor utilizes a wire-grid beamsplitter with imaging systems positioned at each output to analyze two orthogonal linear polarization states simultaneously. Combined with a form birefringent wave plate, the system is capable of snapshot imaging polarimetry in any one Stokes parameter (S1, S2 or S3). Radiometric and polarimetric calibration procedures for the instrument are provided and data from the instrument are presented, demonstrating the ability to measure intensity variations corresponding to polarized emission in natural environments. As such, emission polarimetry can be exploited at significantly reduced cost, sensor size and power consumption over instruments based on more costly Mercury-Cadmium Telluride (MCT) FPA's.

Channeled spectropolarimetry, first developed by K. Oka, is capable of measuring all the Stokes parameters from a single modulated spectrum. We present a theoretical means for improving the spectral resolution of channeled spectropolarimetry by at least a factor of four. Especially valuable in the infrared due to atmospheric absorption features, this method simultaneously provides for the correction of aliasing artifacts from the channels used for the determination of the Stokes parameters. The technique is experimentally demonstrated using a Fourier transform infrared spectrometer and two multiple-order Yttrium Vanadate (YVO4) retarders. This approach is implemented with consideration of crystal dichroism effects, and reconstructions are compared with conventional channeled spectropolarimetric reconstructions from the same system. Additional results, produced by using Cadmium Sulfide (CdS) retarders, provide demonstration of the technique across the infrared.

We present the design, fabrication, characterization of spatially variable infrared filter and a demonstration of the filter as a simple infrared spectrometer. A varying photonic band gap filter which consists of thermally evaporated, high refractive index contrast amorphous chalcogenide glass multilayers, makes the structure suitable to be used as spectrometer. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 2 to 8 μm wavelengths. It is demonstrated that the filter can be used to detect absorption peaks of common gases in the cavity mode range of the filter.

Unipolar barriers can block one carrier type but allow the un-impeded flow of the other. They can be used to implement the barrier infra-red detector (BIRD) design for increasing the collection efficiency of photo-generated carriers, and reducing dark current generation without impeding photocurrent flow. In particular, the InAs/GaSb/AlSb material system, which can be epitaxially grown on GaSb or InAs substrates, is well suited for implementing BIRD structures, as there is considerable flexibility in forming a variety of alloys and superlattices, and tailoring band offsets. We describe our efforts to achieve high-performance long wavelength InAs/GaSb superlattice infrared photodetectors based on the BIRD architecture. Specifically, we report a 10 μm cutoff device based on a complementary barrier infrared detector (CBIRD) design. The detector, without anti-reflection coating, exhibits a responsivity of 1.5 A/W and a dark current density of 1×10^-5 A/cm² at 77K under 0.2 V bias. It reaches 300 K background limited infrared photodetection (BLIP) operation at 101 K, with a black-body BLIP D* value of 2.6×10¹⁰ cm-Hz^1/2/W for 2π field of view under 0.2 V bias.

A new feedback readout circuit of microbolometers for sensing radiant power is proposed in this paper. Due to excellent thermal characteristics of microstructure on infrared application recently, the readout circuits of the microsensors would not concern the responsivity only, but should also take offset voltage cancellation, digitalization, and signal-to-noise ratio under considerations. Although Wheatstone bridge readout circuit has been widely used in resistive thermal sensor readout for several decades, its nonlinear output voltage acting as the offset voltage still perplex us, as well as its digitalization and signal-to-noise ratio could be unsatisfied for microbolometer applications. Hence, we present the feedback readout which could optimize the key factors simultaneously and increase the responsivity without any layout modification of the bridge structure on Infrared Focal Plane Array (IRFPA) microbolometer chip. The results revealed that the balanced parameter, frequency, equal to 0.5 would be the best condition for these requirements instead of the balanced parameter equal to unity by intuition traditionally. Compared to traditional Wheatstone bridge readout circuit, the feedback readout circuit would improve the responsivity of 2.86 times, immunize the offset voltage exactly, obtain a very large OVRR, and reduce the noise of the readout circuit of 5.6 dB. These significantly important results will improve significantly the performance of the readout circuit, and speed up the commercialization of infrared focal plane array of microbolometers.

An overview of the properties of the absorption coefficient of mercury cadmium telluride that may make this material useful for intrinsic hyperspectral detection is presented. A review of recent work on modeling the absorption coefficient is provided, and new directions for achieving an analytical representation with higher fidelity are suggested.

It is suggested to use a precision thermal receiver built as a trap detector and consisting of "basic" thermal receivers to create a standard comparison for optic emission. A metering problem is then stated for a stand-alone "basic" receiver, and principal relations are defined to allow calculation of its stationary temperature mode, while taking into consideration radiant and convective heat losses.

Mercury Cadmium Telluride (HgCdTe) is the material of choice for the majority of high performance infrared focal plane array (IRFPA) systems fielded in the Army with state-of-the-art HgCdTe growth using a bulk Cadmium Zinc Telluride (CdZnTe) substrate. However, as the push for larger array sizes continues, it has been recognized that an alternative substrate technology will be required for HgCdTe IRFPAs. A major effort has been placed in developing CdTe/Si as such a substrate. Although successful for short-wavelength (SWIR) and mid-wavelength (MWIR) focal plane arrays, current HgCdTe/Si material quality is insufficient for long-wavelength (LWIR) arrays due to the high density of dislocations present in the material. In this paper, we will discuss several processes being developed at the U.S. Army Research Laboratory (ARL) to overcome this issue. Effort has been placed on both composite substrate development and improvement, and on HgCdTe/Si post-growth processes. Recently, we have demonstrated HgCdTe/Si material with dislocation density measuring 1 × 10⁶ cm^-2. This is a five times reduction in the baseline material dislocation density currently used in the fabrication of devices.

The observation of astrophysical objects in the mid-infrared requires Blocked Impurity Band (BIB) detectors based on n-doped Silicon. It is desirable to observe faint astronomical objects with such a detector, which can be achieved with a high Signal to Noise ratio. One possibility is an implemented Depleted P-channel Field Effect Transistor (DEPFET) Active Pixel Sensor (APS)¹ on the BIB detector in order to be free of interconnection stray capacitance. A noise of 2 e^- ENC and a current amplification of 300 pA per e^- can be obtained at room temperature. These detectors operate at a temperature range from 6 K to 12 K. The DEPFET is operated under these conditions to investigate the functional principle of the detector. We show results of characteristic and dynamic measurements of the single pixel DEPFET at low temperature. We irradiate the DEPFET single pixel with x-rays originating from the nuclear decay of Fe55 and take a spectrum of the K_α- and Kβ-line. Uncomplete clear is identified with freeze-out of the signal charge into ionized shallow donor states in the heavily doped internal Gate of the DEPFET due to low thermal energy. We found a solution to emit the localized signal charges into the conduction band in order to ensure the transport from the internal Gate to the Clear contact.

We present the design and development of a negative feedback devices using the internal discrete amplifier approach used for the development of a single photon avalanche photodetector in the near infrared wavelength region. This new family of photodetectors with negative feedback, requiring no quenching mechanism using Internal Discrete Amplification (IDA) mechanism for the realization of very high gain and low excess noise factor in the visible and near infrared spectral regions, operates in the non-gated mode under a constant bias voltage. The demonstrated device performance far exceeds any available solid state Photodetectors in the near infrared wavelength range. The measured devices have Gain > 2×10⁵, Excess noise factor < 1.05, Rise time < 350ps, Fall time < 500ps, Dark current < 2×10⁶ cps at room temperature, and Operating Voltage < 60V. These devices are ideal for researchers in the field of Ladar/Lidar, free space optical communication, 3D imaging, industrial and scientific instrumentation, night vision, quantum cryptography, and other military, defence and aerospace applications.

This paper presents the design of quarter-wave retarders for the Dense Wave Division Multiplexing using parallel mirrors coated with a single layer. The output light from the device is parallel to the input light and displaced by a distance d. The quarter-wave retarder total reflection is in the range of 83%. Error analysis on the design is also presented. The error analysis shows how changes on the angle of incident light and the thin film thicknesses affect the design of the retarders.

A novel detector, incorporating e2v's L3 CCD (L3Vision^TM) [1] technology for use in LIDAR (Light Detection And Ranging) applications has been designed, manufactured and characterised. The most critical performance aspect was the requirement to collect charge from a 120μm square detection area for a 667ns temporal sampling window, with low crosstalk between successive samples, followed by signal readout with sub-electron effective noise. Additional requirements included low dark signal, high quantum efficiency at the 355nm laser wavelength and the ability to handle bright laser echoes, without corruption of the much fainter useful signals. The detector architecture used high speed charge binning to combine signal from each sampling window into a single charge packet. This was then passed through a multiplication register (EMCCD) operating with a typical gain of 100X to a conventional charge detection circuit. The detector achieved a typical quantum efficiency of 80% and a total noise in darkness of < 0.5 electrons rms. Development of the detector was supported by ESA.

In this paper, we report the latest results on our development of delta-doped, thinned, back-illuminated CMOS imaging arrays. As with charge-coupled devices, thinning and back-illumination are essential to the development of high performance CMOS imaging arrays. Problems with back surface passivation have emerged as critical to the prospects for incorporating CMOS imaging arrays into high performance scientific instruments, just as they did for CCDs over twenty years ago. In the early 1990's, JPL developed delta-doped CCDs, in which low temperature molecular beam epitaxy was used to form an ideal passivation layer on the silicon back surface. Comprising only a few nanometers of highly-doped epitaxial silicon, delta-doping achieves the stability and uniformity that are essential for high performance imaging and spectroscopy. Delta-doped CCDs were shown to have high, stable, and uniform quantum efficiency across the entire spectral range from the extreme ultraviolet through the near infrared. JPL has recently bump-bonded thinned, delta-doped CMOS imaging arrays to a CMOS readout, and demonstrated imaging. Delta-doped CMOS devices exhibit the high quantum efficiency that has become the standard for scientific-grade CCDs. Together with new circuit designs for low-noise readout currently under development, delta-doping expands the potential scientific applications of CMOS imaging arrays, and brings within reach important new capabilities, such as fast, high-sensitivity imaging with parallel readout and real-time signal processing. It remains to demonstrate manufacturability of delta-doped CMOS imaging arrays. To that end, JPL has acquired a new silicon MBE and ancillary equipment for delta-doping wafers up to 200mm in diameter, and is now developing processes for high-throughput, high yield delta-doping of fully-processed wafers with CCD and CMOS imaging devices.

EO/IR Nanosensors are being developed for a variety of Defense and Commercial Systems Applications. These include UV, Visible, NIR, MWIR and LWIR Nanotechnology based Sensors. The conventional SWIR Sensors use InGaAs based IR Focal Plane Array (FPA) that operate in 1.0-1.8 micron region. Similarly, MWIR Sensors use InSb or HgCdTe based FPA that is sensitive in 3-5 micron region. More recently, there is effort underway to evaluate low cost SiGe visible and near infrared band that covers performance up to 1.6 micron. The use of Nanowires for developing high quality antireflection coatings that allows minimizing the reflection loss is discussed. We have explored the possibility of using nanostructures grown by oblique angle deposition technique. A graded-index coating with different index profiles has been investigated for broadband antireflection properties, particularly with air as the ambient medium. In this paper, we present, modeling and experimental results for nanostructure AR coatings for UV, Visible and calculations for NIR sensors and also their utility for longer wavelength application.

High resolution imaging in UV band has a lot of applications in Defense and Commercial systems. The shortest wavelength is desired for spatial resolution which allows for small pixels and large formats. UVAPD's have been demonstrated as discrete devices demonstrating gain. The next frontier is to develop UV APD arrays with high gain to demonstrate high resolution imaging. We will discuss an analytical model that can predict sensor performance in the UV band using p-i-n or APD detectors with and without gain and other detector and sensor parameters for a desired UV band of interest. SNR's can be modeled from illuminated targets at various distances with high resolution under standard MODTRAN atmospheres in the UV band and the solar blind region using detector arrays with unity gain and with high gain APD along with continuous or pulsed UV lasers. The performance can be determined by the signal level which results from the UV laser return energy (laser power, beam divergence, target reflectance and atmospheric transmittance), the optics f/number, the response of the detector (collection area, quantum efficiency, fill factor and gain), and the total noise which will be the sum of the dark current noise, the scene noise, and the amplifier noise. We also discuss trades as a function of detector response, dark current noise and the 1/f noise. We also present various approaches and device designs that are being evaluated for developing APD's in wide band gap semiconductors. The paper also discusses current state of the art in UV APD and the future directions for small unit cell size and gain in the APD's.

Range-resolved reflective tomography using short pulselength lasers has been shown to be an image reconstruction method which can be used to recover image information about an object with a non-imaging laser radar (ladar) system. The resulting time-dependent return signal (Project) is collected by a non-imaging optical system, which provides a onedimensional signal as a function of range. This paper presents a short pulselength direct-detect laser reflective tomography imaging ladar, and gives the image reconstruction results. In order to efficiently improve and modify the algorithms developed for reflective tomography, we develop a new imaging reconstruction algorithm.

The filtered back-projection algorithm is referenced and used for reflective tomography laser radar imaging reconstruction because of its simplicity and computational efficiency. Due to the divergence angle of the laser beam, wave front becomes fanned surface. However, direct fan-beam filtered back-projection imaging algorithm with the fan-beam reflective projection data exits huge computational complexity and long time consuming. To solve this question, the double broken lines filtered back-projection algorithm is introduced to implement the image reconstructions. Fan-beam reflective data is filtered and back-projected to the double broken lines with corresponding angles and distances. Images reconstructed by fan-beam filtered back-projection and double broken lines filtered back-projection are compared by computer simulation based on reflective projection data. The simulation results show that double broken lines filtered back-projection algorithm is effective in solving the computational complexity problem in image reconstruction without compromising the image resolution, also with the increasing distance between the detector and the target, the images reconstructed by the double broken lines filtered back-projection are increasing closely to the reference image.

Almost two years after the investors in Sarcon Microsystems pulled the plug, the micro-cantilever array based uncooled IR detector technology is again attracting more and more attention because of its low cost and high credibility. An uncooled thermal detector array with low NETD is designed and fabricated using MEMS bimaterial microcantilever structures that bend in response to thermal change. The IR images of objects obtained by these FPAs are readout by an optical method. For the IR images, one of the most problems of FPN is complicated by the fact that the response of each FPA detector changes due to a variety of factors, causing the nonuniformity pattern to slowly drift in time. Thus, it is required to remove the nonuniformity. A scene-based nonuniformity correction algorithm was discussed in this paper, against to the traditional calibration-based and other scene-based techniques, which has the better correct performance; better MSE compared with traditional methods can be obtained. Great compute and analysis have been realized by using the discussed algorithm to the simulated data and real infrared scene data respectively. The experimental results demonstrate, the corrected image by this algorithm not only yields highest Peak Signal-to-Noise Ratio values (PSNR), but also achieves best visual quality.

In this work, a photodiode for the visible spectral range, which will be integrated monolithically with CMOS circuits, is presented. Such Optoelectronic Integrated Circuit (OEIC) with high sensitivity in the 400-900 nm spectral range is utilized to realize electronic processing from the light beam position that hit a specific area of the photodetector. The output signals with voltages of 0V and 3 V can be implemented with a controller circuit. By the Using of He-Ne Laser at 633 nm as incident light, the responsivity of the Position Sense Photodetector (PSPD) was 0.35 A/W and the rise and fall time of less than 30 ns were achieved. These parameters were necessaries to achieve the photodiode integration in an industrial 0.5 μm CMOS process, only additional mask was needed in order to block out the threshold voltage implantation in the photo-active region. Therefore both designs of photodiode and the electronic processing circuit separately, are shown here, all design will be integrated monolithically in the same Silicon chip.

We propose an Eye Tracker/Display system, based on a novel, dual function device termed ETD, which allows sharing the optical paths of the Eye tracker and the display and on-chip processing. The proposed ETD design is based on a CMOS chip combining a Liquid-Crystal-on-Silicon (LCoS) micro-display technology with near infrared (NIR) Active Pixel Sensor imager. The ET operation allows capturing the Near IR (NIR) light, back-reflected from the eye's retina. The retinal image is then used for the detection of the current direction of eye's gaze. The design of the eye tracking imager is based on the "deep p-well" pixel technology, providing low crosstalk while shielding the active pixel circuitry, which serves the imaging and the display drivers, from the photo charges generated in the substrate. The use of the ETD in the HMD Design enables a very compact design suitable for Smart Goggle applications. A preliminary optical, electronic and digital design of the goggle and its associated ETD chip and digital control, are presented.