SRI International (SRI) has developed a new multi-purpose day/night video camera with low-light imaging performance comparable to an image intensifier, while offering the size, weight, ruggedness, and cost advantages enabled by the use of SRI’s NV-CMOS HD digital image sensor chip. The digital video output is ideal for image enhancement, sharing with others through networking, video capture for data analysis, or fusion with thermal cameras. The camera provides Camera Link output with HD/WUXGA resolution of 1920 x 1200 pixels operating at 60 Hz. Windowing to smaller sizes enables operation at higher frame rates. High sensitivity is achieved through use of backside illumination, providing high Quantum Efficiency (QE) across the visible and near infrared (NIR) bands (peak QE <90%), as well as projected low noise (<2h+) readout. Power consumption is minimized in the camera, which operates from a single 5V supply. The NVCMOS HD camera provides a substantial reduction in size, weight, and power (SWaP) , ideal for SWaP-constrained day/night imaging platforms such as UAVs, ground vehicles, fixed mount surveillance, and may be reconfigured for mobile soldier operations such as night vision goggles and weapon sights. In addition the camera with the NV-CMOS HD imager is suitable for high performance digital cinematography/broadcast systems, biofluorescence/microscopy imaging, day/night security and surveillance, and other high-end applications which require HD video imaging with high sensitivity and wide dynamic range. The camera comes with an array of lens mounts including C-mount and F-mount. The latest test data from the NV-CMOS HD camera will be presented.
Military applications for conventional InGaAs SWIR sensing have been limited by the requirement of thermoelectric
cooler (TEC) temperature stabilization for nonuniformity correction (NUC). TEC operation restricts the
operating temperature range and size, weight, and power (SWAP) of these systems. For battery-powered man
portable and micro UAV applications elimination of the TEC is critical.
This paper discusses the advantages of our non-TEC temperature parameterized NUC corrections algorithms
versus TEC stabilized architectures. The corrections algorithms enable performance-tuned polynomial order
correction of both pixel uniformity and temperature parameterization for each SWIR sensor. These advances
enable SWIR InGaAs sensing to meet the SWAP requirements of next generation military applications.
The increasing demand for short wave infrared (SWIR) imaging technology for soldier-based and unmanned
platforms requires camera systems where size, weight and power consumption are minimized without loss of
performance. Goodrich, Sensors Unlimited Inc. reports on the development of a novel focal plane (FPA) array for
DARPA's MISI (Micro-Sensors for Imaging) Program. This large format (1280 x 1024) array is optimized for
day/night imaging in the wavelength region from 0.4 μm to 1.7 μm and consists of an InGaAs detector bump bonded to a
capacitance transimpedance amplifier (CTIA)-based readout integrated circuit (ROIC) on a compact 15 μm pixel pitch.
Two selectable integration capacitors provide for high dynamic range with low (< 50 electrons) noise, and expanded onchip
ROIC functionality includes analog-to-digital conversion and temperature sensing. The combination of high
quality, low dark current InGaAs with temperature-parameterized non-uniformity correction allows operation at ambient
temperatures while eliminating the need for thermoelectric cooling. The resulting lightweight, low power
implementation is suitable for man-portable and UAV-mounted applications.
Goodrich, SUI has developed a 15 μm pitch, 1280 x 1024 pixel InGaAs focal plane array (FPA) with low noise, and
visible to near infrared (0.4 μm to 1.7 μm) wavelength response for day and night vision applications. The readout
integrated circuit (ROIC), which uses a capacitive transimpedance amplifier (CTIA) pixel, is designed to achieve a noise
level of less than 50 electrons, due to its small integration capacitor. The ROIC can be read out at 120 frames per second,
and has a dynamic range of 3000:1 using rolling, non-snapshot integration. The ROIC was fabricated in a standard
CMOS foundry process, and was bump-bonded to Vis-InGaAsTM detector arrays. SUI has successfully hybridized 15 μm
pitch 1280 x 1024 pixel FPAs, and produced imagery.
The DARPA PCAR program is sponsoring the development of low noise, near infrared (1.5 &mgr;m wavelength) focal
plane arrays (FPAs) for night vision applications. The first phase of this work has produced a collection of 640 x 512
pixel, 20 &mgr;m pitch FPAs with low noise. The approach was to design four different read out integrated circuits
(ROICs), all compatible with the same bump-bonded InGaAs photodiode detector array. Two of the designs have
capacitive transimpedance amplifier (CTIA) pixels, each with a somewhat different amplifier design and with two
different sizes of small integration capacitors. The third design is a source follower per detector (SFD) pixel,
integrating on the detector capacitance. The fourth design also integrates on the detector capacitance, but uses a
moderate gain, in-pixel amplifier to boost the signal level, and also has a differential pixel output. All four designs
require off-chip correlated sampling to achieve the desired noise level. The correlated sampling is performed digitally
in the data acquisition software. Each design is capable of 30 frames per second read out rate, and has a dynamic range
of 1000:1 using a rolling, non-snapshot integration. The designs were fabricated in a standard CMOS foundry process,
and were bump-bonded to InGaAs detector arrays. All four designs are working without any significant design errors,
and are producing low noise imaging, with less than 50 electrons rms noise per pixel after correlated double sampling.
We report on a 640 x 512 pixel, 25 μm pitch, InGaAs focal plane array based camera with the ability to perform range-gated imaging, while also allowing integration times longer than 32 ms for imaging in a staring mode at video rates. The combination of gated and video imaging is achieved through a high bandwidth pixel with a capacitive transimpedance amplifier (CTIA) design. The CTIA pixel may be switched between two feedback capacitor sizes to allow two different sensitivities and capacities, depending on the illumination conditions. Anti-blooming is included in the pixel to prevent charge spreading from oversaturated pixels. All pixels are gated simultaneously for "snapshot" exposure. The all solid-state gated camera is very reliable, in addition to being small and lightweight. The low dark current and high bandwidth of the InGaAs photodetectors enables both high sensitivity imaging at long exposure times and high bandwidth at short exposure times. The spectral response of InGaAs extends from 0.9 μm to 1.7 μm, allowing the use of eye-safe commercially available pulsed lasers with 1.5 μm wavelength, several millijoule pulse energies, and nanosecond scale pulse durations.
We report on our 640x512 pixel InGaAs/InP focal plane array camera for visible and short-wavelength infrared imaging. For this camera, we have fabricated a 640x512 element substrate-removed backside-illuminated InGaAs/InP photodiode array (PDA) with a 25 mm pixel pitch. The PDA is indium bump bonded to a silicon read out integrated circuit. Removing the InP substrate from the focal plane array allows visible wavelengths, which would otherwise be absorbed by the InP substrate due to its 920 nm wavelength cut-off, to reach the pixels' active region. The quantum efficiency is approximately 15% at 500 nm, 70% at 850 nm, 85% at 1310 nm, and 80% at 1550 nm.
Features incorporated into this video-rate, 14-bit output camera include external triggering, windowing, individual pixel correction, 8 operational settings of gain and exposure time, and gamma correction. The readout circuit uses a gate-modulated pixel for high sensitivity imaging over a wide illumination range. This camera is useable for visible imaging as well as imaging eye-safe lasers and is of particular interest seeing laser designators and night vision as well as hyperspectral imaging.
Many applications, such as industrial inspection and overhead reconnaissance benefit from line scanning architectures where time delay integration (TDI) significantly improves sensitivity. CCDs are particularly well suited to the TDI architecture since charge is transferred virtually noiselessly down the column. Sarnoff's TDI CCDs have demonstrated extremely high speeds where a 7200 x 64, 8 um pixel device with 120 output ports demonstrated a vertical line transfer rate greater than 800 kHz.
The most recent addition to Sarnoff's TDI technology is the implementation of extended dynamic range (XDR) in high speed, back illuminated TDI CCDs. The optical, intrascene dynamic range can be adjusted in the design of the imager with measured dynamic ranges exceeding 2,000,000:1 with no degradation in low light performance. The device provides a piecewise linear response to light where multiple slopes and break points can be set during the CCD design. A description of the device architecture and measured results from fabricated XDR TDI CCDs are presented.
New applications for ultra-violet imaging are emerging in the fields of drug discovery and industrial inspection. High throughput is critical for these applications where millions of drug combinations are analyzed in secondary screenings or high rate inspection of small feature sizes over large areas is required. Sarnoff demonstrated in1990 a back illuminated, 1024 X 1024, 18 um pixel, split-frame-transfer device running at > 150 frames per second with high sensitivity in the visible spectrum. Sarnoff designed, fabricated and delivered cameras based on these CCDs and is now extending this technology to devices with higher pixel counts and higher frame rates through CCD architectural enhancements. The high sensitivities obtained in the visible spectrum are being pushed into the deep UV to support these new medical and industrial inspection applications. Sarnoff has achieved measured quantum efficiencies > 55% at 193 nm, rising to 65% at 300 nm, and remaining almost constant out to 750 nm. Optimization of the sensitivity is being pursued to tailor the quantum efficiency for particular wavelengths. Characteristics of these high frame rate CCDs and cameras will be described and results will be presented demonstrating high UV sensitivity down to 150 nm.
A family of backside illuminated CCD imagers with 6.6 micrometers pixels has been developed. The imagers feature full 12 bit (> 4,000:1) dynamic range with measured noise floor of < 10 e RMS at 5 MHz clock rates, and measured full well capacity of > 50,000 e. The modulation transfer function performance is excellent, with measured MTF at Nyquist of 46% for 500 nm illumination. Three device types have been developed. The first device is a 1 K X 1 K full frame device with a single output port, which can be run as a 1 K X 512 frame transfer device. The second device is a 512 X 512 frame transfer device with a single output port. The third device is a 512 X 512 split frame transfer device with four output ports. All feature the high quantum efficiency afforded by backside illumination.
A backside illuminated time delay integration (TDI) charge coupled device (CCD) technology has been developed. Imagers have been demonstrated at 13 pm pixel size and 8 pm pixel size. Photocomposition (stitching) has been employed to realize TDI iinagers of length < 60 mm. Performance has been enhanced in the areas of quantum efficiency, dynamic range, modulation transfer function (MTF), and line scan rates. The focus of this work has been to develop this new generation of line scan imagers for advanced reconnaissance applications. The enhancements permit the deployment of new camera systems with higher sensitivity, and higher resolution. To support the deployment of this technology into rugged environments, a custom packaging technology has been 'developed. The packages provide a hermetic enclosure for the CCD and establish precise alignment of the CCD pixels to the package mounting fixture. This paper will summarize the design features of the 13 pm pixel and 8 jim pixel TDI arrays. Measured performance will be presented. Future plans for this backside illuminated TDI technology will be discussed.