Roger W. Graham

Advanced IRFPAs for next-generation sensors

Raytheon Vision Systems (RVS) has invented and demonstrated a new class of advanced focal plane arrays. These Advanced FPAs are sometimes called 3rd Generation or “Next Generation” FPAs because they have integrated onto the FPA the ability to sense multiple IR spectrums, have improved resolution and performance, and conduct image processing on the FPA ROIC. These next generation of FPAs are allowing more functionality and the detection of a more diverse set of data than previously possible with 2nd Gen FPAs. Examples and history of advanced next generation FPAs are reviewed including RVS’s Multispectral, Uncooled, Adaptive Sensors and other advanced sensors.

High operating temperature mid-wavelength infrared HgCdTe photon trapping focal plane arrays

This paper investigates arrays of HgCdTe photon trapping detectors. Performance of volume reduced single mesas is compared to volume reduced photon trap detectors. Good agreement with model trends is observed. Photon trap detectors exhibit improved performance compared to single mesas, with measured noise equivalent temperature difference (NEDT) of 40 mK and 100 mK at temperatures of 180 K and 200 K, with good operability. Performance as a function of temperature has also been investigated.

Large-format HgCdTe focal plane arrays for dual-band long-wavelength infrared detection

Raytheon Visions Systems (RVS) is furthering its capability to deliver state-of-the-art high performance large format HgCdTe focal plane arrays (FPAs) for dual-band long-wavelength infrared (LWIR) detection. Missile seekers are designed to acquire targets of interest at long ranges and discriminate targets from clutter. The use of dual-band long wavelength infrared detector technology provides the ability for these seekers to combine these operations into the same package with enhanced performance. Increasing the format size of dual-band longwavelength FPAs and tailoring the detector design for specific long-wavelength bands enables seekers to be designed for increased field-of-view, longer target acquisition ranges, and improved accuracy. This paper will review in further detail the aspects of detector design, MBE wafer growth, wafer fabrication, and detector characterization that are contributing to development and demonstration of high performance large format dual-band LWIR FPAs at RVS.

Signal processing on the focal plane array: an overview

Raytheons Infrared Operations (RIO) has invented and developed a new class of focal plane arrays; the Adaptive IR Sensor (AIRS) and Thinfilm Analog Image Processor (TAIP). The AIRS FPA is based upon biologically inspired on-focal- plane circuitry, which adaptively removes detector and optic temperature drift and l/f induced fixed pattern noise. This third-generation multimode IRFPA, also called a Smart FPA, is a 256x256-array format capable of operation in four modes: 1) Direct Injection (DI), 2) Adaptive Non-uniformity Correction (NUC), 3) Motion/Edge Detection, and 4) Subframe Averaging. Also the 320x240 TAIP results have shown excellent image processing in the form of Spatial and Temporal processing.

Staring MWIR, LWIR and 2-color and scanning LWIR polarimetry technology

Polarimetry sensor development has been in work for some time to determine the best use of polarimetry to differentiate between manmade objects and objects made by nature. Both MWIR and LWIR and 2-color staring Focal Plane Arrays (FPAs) and LWIR scanning FPAs have been built at Raytheon Vision Systems each with exceedingly higher performance. This paper presents polarimetric performance comparisons between staring 2562 MWIR, 2562 LWIR, 5122 LWIR/LWIR staring FPAs and scanning LWIR FPAs. LWIR polarimetry has the largest polarimetric signal level and a larger emissive polarimetric signature than MWIR which makes LWIR less dependent on sun angles. Polished angled glass and metal objects are easily detected using LWIR polarimetry. While single band 9-11 um LWIR polarimetry has advantages adding another band between 3 and 7 um improves the capability of the sensor for polarization and spectral phenomenology. In addition the 3-7 um band has improved NEDT over the 9-11 um band due to the shorter detector cutoff reducing the Noise Equivalent Degree of Linear Polarization. (NEDOLP). To gain acceptance polarimetric sensors must provide intelligence signatures that are better than existing nonpolarimetric Infrared sensors. This paper shows analysis indicating the importance of NEDOLP and Extinction ratios.

Toward a retinal prosthesis for the blind: advanced microelectronics combined with a nanochannel glass electrode array

An important new area of biomedical engineering is the development of neural prosthesis particularly in the area of cochlear and retinal devices. An intraocular retinal prosthesis test device is currently under development at NRL/JHU. The microelectronic device has an image format of 80 x 40 unit cells interfaced to the retinal surface via an array of microwires in a glass matrix. The system architecture and technology development issues are discussed as well as the topic of biocompatibility. This test device will enable acute human experiments in an operating room environment to demonstrate a massively parallel interface between retinal tissue and a microelectronic array.