Small Pixel High Definition (SPHD) IR Cameras continue to improve in performance, resolution, and yield. SPHD product adoption is helping drive important performance goals such as sensitivity, resolution and other features. We report on continued developments of high-resolution small pitch infrared camera system technology developed at Cyan Systems. We highlight demonstrated imaging capability from two recent, large format, infrared focal plane array architectures. Specifically, we present results from our full-high-definition (FHD) 5-micron pixel CS-3 camera now capable of broadband (~0.7 – 5.0 micron) wavelength sensitivity. We show more results from our newest digital readout integrated circuit (DROIC) small pixel mid-wave infrared camera with ultra-high-definition (3840 x 2160) format, and Cyans CS-3 full-high-definition (1920 x 1080) Broadband IR camera.
Cyan Systems has continued to mature our small pixel camera performance, including improvements in the packaging, optics, and electronics. The associated camera components demonstrate key resolution and enabling capabilities. We report on recent results from our new digital readout integrated circuit (DROIC) small pixel mid-wave infrared camera with an ultra-high-definition (3840 x 2160) format, in addition to demonstrations with Cyan’s CS-3 full-high-definition (1920 x 1080) camera. We address small pixel spatial sampling and modulation transfer function issues as the pixel size shrinks, and we examine the difference between the performance of present devices and the new generation of small pixel cameras.
Cyan Systems has developed and made multiple improvements on our small pixel camera performance including low noise and compact size, weight, and power. The associated camera components demonstrate key resolution and enabling capabilities. Performance data from compact our new small pixel broadband full high-definition (1920x1080) camera technology is presented. We also report on recent results from our new digital readout integrated circuit (DROIC) small pixel mid-wave infrared camera with an ultra high-defintion (3840x2160) format.
High performance infrared focal plane arrays (FPAs) play a critical role in a wide range of imaging applications. However the high cost associated with the required cooling and serially processed die-level hybridization is major barrier that has thwarted Mid-wavelength Infrared (MWIR) detector technology from penetrating largevolume, low-cost markets. Under the Defense Advanced Research Projects Agency (DARPA) WIRED program, the HRL team has developed a wafer level integration schemes to fabricate large format Antimonidebased MWIR FPAs on Si Read Out Integrated Circuit (ROIC) as a means to achieve significant fab cost reduction and enhanced production scalability. The DARPA-hard challenge we are addressing is the thermal and stress management in the integration of two dissimilar materials to avoid detector and ROIC degradation and to maintain structure integrity at the wafer scale. In addition, a digital ROIC with extremely large well capacity was designed and taped-out, in order to increase the operating temperature of the FPAs. In this talk, we discuss our progress under the DARPA WIRED program.
Barrier detectors based on III-V materials have recently been developed to realize substantial improvements in the performance of mid-wave infrared (MWIR) detectors, enabling FPA performance at high operating temperatures. The relative ease of processing the III-V materials into large-format, small-pitch FPAs offers a cost-effective solution for tactical imaging applications in the MWIR band as an attractive alternative to HgCdTe detectors. In addition, small pixel (5-10μm pitch) detector technology enables a reduction in size of the system components, from the detector and ROIC chips to the focal length of the optics and lens size, resulting in an overall compactness of the sensor package, cooling and associated electronics. To exploit the substantial cost advantages, scalability to larger format (2kx2k/10μm) and superior wafer quality of large-area GaAs substrates, we have fabricated antimony based III-V bulk detectors that were metamorphically grown by MBE on GaAs substrates. The electro-optical characterization of fabricated 2kx2k/10μm FPAs shows low median dark current (3 x 10-5 A/cm2 with λco = 5.11μm or 2.2 x 10-6 A/cm2 with λco = 4.6μm) at 150K, high NEdT operability (3x median value) >99.8% and >60% quantum efficiency (non-ARC). In addition, we report our initial result in developing small pixel (5μm pitch), high definition (HD) MWIR detector technology based on superlattice III-V absorbing layers grown by MBE on GaSb substrates. The FPA radiometric result is showing low median dark current (6.3 x 10-6 A/cm2 at 150K with λco = 5.0μm) with ~50% quantum efficiency (non-ARC), and low NEdT of 20mK (with averaging) at 150K. The detector and FPA test results that validate the viability of Sb-based bulk and superlattice high operating temperature MWIR FPA technology will be discussed during the presentation.
We describe our recent results in developing and maturing small pixel (5μm pitch), high definition (HD) mid-wave infrared (MWIR) detector technology as well as focal-plane-array (FPA) hybrids, and prototype 2.4 Megapixel camera development operating at high temperature with low dark current and high operability. Advances in detector performance over the last several years have enabled III-V high operating temperature (T≥150K), unipolar detectors to emerge as an attractive alternative to HgCdTe detectors. The relative ease of processing the materials into large-format, small-pitch FPAs offers a cost-effective solution for tactical imaging applications in the MWIR band. In addition, small pixel detector technology enables a reduction in size of the system components, from the detector and ROIC chips to the focal length of the optics and lens size, resulting in an overall compactness of the sensor package, cooling and associated electronics. An MBE system has been used to grow antimony-based detector structures with 5.1μm cutoff with low total thickness variation (TTV) across a 3” wafer, in order to realize high interconnect yield for small-pitch FPAs. A unique indium bump scheme is proposed to realize 5μm pitch arrays with high connectivity yield. Several 1kx2k /5μm hybrids have been fabricated using Cyan’s CS3 ROICs with proper backend processing and finally packaged into a portable Dewar camera. The FPA radiometric result is showing low median dark current of 2.3x10-5 A/cm2 with > 99.9% operability, and >60% QE (without AR coating).
We report on product maturation of small pixel high definition high charge capacity 2.4 Mpixel MWIR Infrared Focal Plane Arrays. This high definition (HD) FPA utilizes a small 5 um pitch pixel size which enables near Nyquist limited sampling with by the optical system of many IR lenses. These smaller sub diffraction pitch pixels enable improved sensitivity and resolution resulting in clear, crisp high contrast imaging with excellent IFOVs even with small focal length lenses. The small pixel IR sensor allows the designer to trade off field of view, MTF, optics F/# to obtain a more compact and high performance IR sensor. This enables lower size, power and weight reductions of the entire IR Sensor System. The highly sensitive MWIR small pixel HD FPA has the capability to detect dimmer signals at longer ranges than previously demonstrated.
We report on the demonstration of a high definition high charge capacity 2.1 Mpixel mid-wave infrared (MWIR) Focal Plane Array (FPA). This high definition (HD) FPA utilizes a 2040 x 1156 format and a 5 μm pixel pitch. This small pixel size enables sampling at spatial frequencies greater than the classical Nyquist limit imposed by the optical systems Point Spread Function (PSF). We show that oversampling IRFPAs (Infrared FPA) enable improved fidelity in imaging including resolution improvements, advanced pixel correlation processing to reduce false alarm rates, improved detection ranges, and an improved ability to track closely spaced objects. The small pixel IRFPA achieves good performance in the MWIR band and is expected to detect dimmer signals at longer ranges than previously demonstrated.
We report on a new high definition high charge capacity 2.1 Mpixel MWIR Infrared Focal Plane Array. This high definition (HD) FPA utilizes a small 5 um pitch pixel size which is below the Nyquist limit imposed by the optical systems Point Spread Function (PSF). These smaller sub diffraction limited pixels allow spatial oversampling of the image. We show that oversampling IRFPAs enables improved fidelity in imaging including resolution improvements, advanced pixel correlation processing to reduce false alarm rates, improved detection ranges, and an improved ability to track closely spaced objects. Small pixel HD arrays are viewed as the key component enabling lower size, power and weight of the IR Sensor System. Small pixels enables a reduction in the size of the systems components from the smaller detector and ROIC array, the reduced optics focal length and overall lens size, resulting in an overall compactness in the sensor package, cooling and associated electronics. The highly sensitive MWIR small pixel HD FPA has the capability to detect dimmer signals at longer ranges than previously demonstrated.
Cyan Systems is developing a new Extremely High Temperature Projector System Technology (XTEMPS). The XTEMPS is a multispectral emitter array based upon photonic crystals, providing high radiance and tailored spectral emission in infrared (IR) bands of interest. Cyan has teamed with a state of the art MEMS fabrication facility, Sandia National Laboratories, to develop metallic photonics crystals designed for scene projection systems. Photonic crystals have improved output power efficiency when compared to broad band "graybody" emitters due to limiting the emission to narrow bands. Photonic crystal based emitter pixels have potential for higher effective radiance output, while filtering out energy in the forbidden bandgap. Cyan has developed pixel designs using a medium format RIIC from Nova Sensors that ensures high apparent output temperatures with modest drive currents, and low voltage requirement goals of < 5 V. Cyan has developed a pixel structure for high radiative efficiency of the photonic lattice, while suppressing undesired IR sidelobes. Cyan will provide XTEMPS system performance metrics and illustrate with test structures.
Nova Sensors, under sponsorship of the Munitions Directorate of the Air Force Research Laboratory, has
developed a readout integrated circuit (ROIC) technology for focal plane arrays (FPAs) that permits an
intelligent use of the available image data; this is especially effective for dealing with the large volume of data
produced by today's large format FPAs. The "Variable Acuity Superpixel Imaging" (VASITM) ROIC
architecture allows for coverage of the entire field of view at high frame rates by permitting larger "superpixels"
to be dynamically formed on the FPA in regions of relative unimportance, thus reducing the total number of
pixel values required to be multiplexed off the FPA. In addition, multiple high-resolution "foveal" regions may
be "flown" around the imager's field of view at a frame rate such that high-value targets may be sampled at the
highest possible spatial resolution that the imager can produce.
Nova Sensors has built numerous camera systems using 320 x 256 and 1K x 1K pixel versions of visible and
infrared VASITM FPAs. This paper reviews the technology and discusses numerous applications for this new
class of imaging sensors.
We report on processing techniques to effectively control the data bandwidth in larger format Focal Plane Array (FPA) sensors. We have developed an image processing architecture for variable acuity FPAs that give a controlled reduction in the data rate via simple circuits that estimate activity on the FPA image plane. Integrated on-FPA signal processing goals are to perform pre-processing that is usually performed downstream in a dedicated processing module. Techniques for image pre-processing described in this paper allow transmitting "active" pixel data while skipping unchanging pixels. These techniques for image pre-processing adjacent to the FPA allows significant reductions in the data rate, size, weight and power for small and low cost systems that cannot work with a large image processing.
We report on the capabilities and efficiencies made possible by placing image processing functions near or
on the Focal Plane Array (FPA). Recent work in advanced near FPA signal processing has shown that it is
possible to migrate many of the heretofore off focal plane image processing tasks onto the Readout
Integrated Circuit (ROIC). The goals of this work are to describe and demonstrate the feasibility of
"Activity Sensing" and the associated computational efficiency with this type of on FPA processing.
Bottleneck reduction, intelligent information processing, and adaptive bandwidth compression are also key
challenges of the next generation FPA architectures with on FPA processing. We report on the
development and performance benefits expected from an Activity Sensing algorithm using recorded
infrared (IR) Data from a large format 1024 × 1024 variable acuity Indium-Antimonide1 FPA sensor.
A wide variety of imaging applications exist for 1K x 1K midwave infrared (MWIR) imagers and Nova's Variable Acuity Superpixel Imager (VASTM) technology1,2 has now progressed to this image format. This paper will demonstrate a variety of imagery from MWIR cameras using this large format "LVASI" device; the in-pixel processing used by the LVASI cameras represents the state-of-the-art for image size, total field of view, high frame rates, low data bandwidths and real-time spatial reprogrammability of focal plane arrays (FPAs). Using these devices, imaging systems may now be implemented that permit the operator to "zoom in" to regions of interest with very high spatial resolution, while covering the remainder of the total field of view (TFOV) at conventional resolutions. The bandwidth compression attainable using these sensors helps to make possible systems that can transmit their high resolution imagery through wireless interconnected networks.
We present recent infrared image data that highlight numerous applications including missile detection/tracking, search/rescue and remote surveillance applications.
With the recent introduction of infrared cameras that have the ability to produce variable acuity imagery, it has become necessary to develop methods for bad pixel replacement and non-uniformity correction within superpixels. Since a superpixel is formed by averaging a group of smaller pixels on chip prior to readout, producing a single value, we cannot apply gains and offsets to the individual pixels that contribute to the superpixel value, nor can we replace bad pixels within a superpixel before they corrupt the aggregate intensity of the superpixel. Without new superpixel correction methods, the imagery produced by this exciting technology is less appealing to human observers and corrupted superpixel intensities lead to problems with the algorithms that process the imagery to perform useful automated tasks, such as "hot-spot" tracking. This paper will introduce a method for performing the non-uniformity and bad pixel corrections in superpixels and demonstrate the performance.
We present a detailed comparison between the operational performance of "conventional" and "foveating" large format infrared focal plane arrays (FPAs). Foveating FPAs provide its users with a substantial advantage when compared with imaging sensors currently in use. This paper details the differences between foveating and traditional FPAs and provides objective comparisons to aid systems designers select the appropriate imaging device for their applications. A variety of on-FPA operations are performed with foveating sensors; some of these operations require the use of a companion processor to spatially reprogram the foveal sensor. We will compare several critical sensor performance parameters including: frame rate, data bandwidth, spatial and temporal noise. In addition, operational comparisons will be made to contrast the various applications that may be best suited for the two respective imaging sensor types.
This paper serves as a companion to SPIE paper 4820-36, presented in Seattle in 2002. Advances in the design and application of “Variable Spatial Acuity” focal plane arrays are reported here, with specific examples of large format imagers and applications to which they are being applied. These devices have been developed through the combined requirements of (a) covering a wide total field of view while (b) retaining the highest possible spatial resolution on the objects of interest while at the same time (c) operating at the highest possible frame rate. Many thousands of frames per second are possible with the prototype imager while maintaining high spatial resolution. The prototype device operates as a visible imager, and we are pursuing the transition of this technology into the infrared domain. This paper will concentrate on applications of the technology and will show some imagery collected with the systems developed for their use.
Nova Research, Inc. has developed a novel two-dimensional imaging chip whose design is based on properties exhibited by biological retinas. The 'Variable Acuity' imager permits the user to program a unique spatial arrangement of 'superpixels' that may be updated in real time. Any spatial configuration of pixels in the imager may be realized by programming the device in a way that permits pixels to share their individually-collected photocharge with any or all neighbors. Single and multiple 'foveal' configurations are possible, and these high spatial resolution regions may be 'flown' around the FPA at the will of the controlling processor. This device was developed through the combined requirements of (a) covering a wide total field of view while (b) retaining the highest possible spatial resolution on the targets of interest while at the same time (c) operating at the highest possible frame rate. Many thousands of frames per second are possible with the prototype imager while maintaining high spatial resolution. The prototype device operates as a visible imager, and Nova is pursuing the transition of this technology into the infrared domain. This paper will concentrate on applications of the technology and will show some imagery collected with the prototype system.
The first-ever operational infrared focal plane that makes use of an architecture which mimics that of the human retina was designed, built, tested and integrated into a demonstration system at Amber Engineering. This paper presents an overview of the design concepts of this device, presents some operational results using the overall system, and discuses some options for system-level uses of future devices which will grow out of our initial experiences.
An infrared focal plane has been simulated, designed and fabricated which mimics the form and function of the vertebrate retina. The `Neuromorphic' focal plane has the capability of performing pixel-based sensor fusion and real-time local contrast enhancement, much like the response of the human eye. The device makes use of an indium antimonide detector array with a 3 - 5 micrometers spectral response, and a switched capacitor resistive network to compute a real-time 2D spatial average. This device permits the summation of other sensor outputs to be combined on-chip with the infrared detections of the focal plane itself. The resulting real-time analog processed information thus represents the combined information of many sensors with the advantage that analog spatial and temporal signal processing is performed at the focal plane. A Gaussian subtraction method is used to produce the pixel output which when displayed produces an image with enhanced edges, representing spatial and temporal derivatives in the scene. The spatial and temporal responses of the device are tunable during operation, permitting the operator to `peak up' the response of the array to spatial and temporally varying signals. Such an array adapts to ambient illumination conditions without loss of detection performance. This paper reviews the Neuromorphic infrared focal plane from initial operational simulations to detailed design characteristics, and concludes with a presentation of preliminary operational data for the device as well as videotaped imagery.
An infrared focal plane has been simulated, designed and fabricated which mimics the form and function of the vertebrate retina. The "Neuromorphic" focal plane has the capability of performing real-time local contrast enhancement, much like the response of the human eye, and operates without saturation over an extremely wide dynamic range due to its logarithmic photoresponse. The device makes use of an indium antimonide detector array with a 3 -5pm spectral response, and a switched capacitor network to compute a real-time 2D spatial average. A gaussian subtraction method is used to produce the pixel output which when displayed produces an image with enhanced edges, representing spatial and temporal derivatives in the scene. The spatial and temporal responses of the device are tunable during operation, permitting the operator to "peak up" the response of the array to spatial and temporally-varying signals, Such an array will adapt to ambient illumination conditions without loss of detection performance. The need to post-process infrared images using digital techniques is thus reduced; seekers making use of this technology could be made smaller due to the reduction of off-plane processing hardware. This paper will review the Neuromorphic infrared focal plane from initial operational simulations to detailed design characteristics, and will conclude with a presentation of preliminary operational data for the device.
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