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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays 5 The Global Landscape of Detector Technologies INTRODUCTION Previous chapters have established the military context and technical bases for addressing evolutionary and emerging, perhaps “breakthrough,” technologies relating to detectors as well as the collection of components and subsystems that constitute a full sensor system. This chapter takes a global view of detectors, sensors, and sensor systems and addresses forces that drive detector development and tend to encourage development more in certain areas of the world than in others. Specific topics are worldwide leaders: government roles, markets, and scale; U.S. export restrictions; and supply-chain bottlenecks. Additional considerations and concluding remarks complete the chapter. The following observations provide a context for the discussions. First, although evidence may emerge of an advance in some aspect of detector- or sensor system-related technologies, an entity’s ability to mature a new technology to producible and deployable states is the ultimate determinant of the utility of that advance. Second, global commercial competition involving detector technologies and sensor systems has become significant. WORLDWIDE LEADERS Several countries are actively involved in the development of infrared (IR) detector technologies. Below is a graphical depiction of open-source publications by country of origin and decade from 1980 to 2010. The data were obtained through
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays a search using Compendex and National Technical Information Service (NTIS) databases. The information contained in Figure 5-1 shows trends in technology interests by country and geographical region. The identification is by the institutional affiliations of the authors. By comparing the number of publications that have emerged from various countries over the last 30 years, one can see acceleration in research reporting by most of the countries shown in Figure 5-1. While the United States maintained dominance, the contributions from the People’s Republic of China more than doubled during the last decade, to about 12 percent of the total. The Web of Science has a different list of open-source publications from which to draw. Web of Science is a citation database with multidisciplinary coverage of more than 10,000 high-impact journals in the sciences, social sciences, and arts and humanities, as well as coverage of international proceedings for more than 120,000 conferences. Figures 5.2 through 5.5 reflect the countries whose papers are drawn from this database. The figures comprise both a 30-year and a 10-year look back and were generated using the search criteria “infrared + detect*.” Figure 5-2 is the 30-year compilation. Figures 5-3 through 5-5 are broken down in 10-year periods to show evolving trends. FIGURE 5-1 Illustrative global infrared detection publication activities.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays FIGURE 5-2 Publications on IR detector technologies from 1980 to 2010 (52,903 results). FIGURE 5-3 Publications on IR detector technologies from 1980 to 1989 (719 results). Conference proceedings are included only from 1990 to the present. Therefore, results in this decade are significantly lower because coverage does not include conference proceedings.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays FIGURE 5-4 1990-1999 Web of Science publications. A total of 16,620 results are found. FIGURE 5-5 2000-2010 Web of Science publications. A total of 35,565 results are found. In looking at the data by decade, two noticeable trends are the decrease in the percentage lead of the United States and the dramatic increase of publications originating from the People’s Republic of China, from not being in the top ten to a strong third place.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays FIGURE 5-6 A representation of joint publication activity on infrared detectors from 2000 to 2010. The size of each country circle represents the number of joint publications from that country, and the weight of the interconnecting lines represents the number of joint publications with joint authorship affiliations from the two countries. There is substantial international collaboration at the research level. Of the publications listed above, 12 percent had authors from multiple countries and 2 percent had authors from three countries or more. This interconnectivity is represented in Figure 5-6, in which the size of the circle is a representation of the number of joint publications with authors from that country and the weight of the interconnecting lines represents the number of joint publications between authors from the two countries. The data are from the Compendex database covering the years 2000-2010. GOVERNMENT ROLES, MARKETS, AND SCALE In some nations, commercial products may be subsidized by governments through direct funding (or indirect assistance, such as tax breaks) for research and development as well as for the infrastructure to manufacture or distribute a product. The incentive “boost” from government funding can accelerate develop-
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays ment and deployment of applications that would otherwise take much longer. Government investments in the commercial arena can have a significant effect on the development and maturation trend for detector and sensor system-related technologies. These developments can be applied to military applications as well as commercial. Some examples of government assistance follow: Declarations of local, regional, or national goals related to detector and sensor technologies; Large investments in major enabling technologies, such as industrial plants and fabrication facilities; Opening of university research centers focused on key technology issues; Efforts to attract major manufacturing players (i.e., analogous to courting a foreign automaker to open a new plant in a particular U.S. state); and Efforts to attract technical leaders, managers, and financial investments in specific technical areas to particular regions. Creation of a government incentive is merely the first step, albeit a large one, in influencing certain technologies. Nonetheless, the decision to create an incentive should be taken as an indicator of where to focus attention and resources when assessing the research, development, and maturation of various classes of detector and sensor technology. One example of apparent foreign government investment is mentioned in Chapter 3 (Box 3-2), suggesting Chinese and Iranian interests in rapid deployments using commodity components. An example of substantial foreign government investment is that of the Chinese government. Sensor and detector laboratory complexes are located in Shanghai, at the Shanghai Institute of Technical Physics (SITP), and at Wuhan, which the Chinese refer to as their “optics valley.” Reports by visitors indicate the following: Active quantum-well IR photodetectors (QWIP) and type II strained superlattice (SLS) programs; III-V materials and InGaAs material-based sensors; HgCdTe material growth and sensor array development; Low Earth orbit and geosynchronous orbit (LEO and GEO) satellite sensor fabrication for weather and Earth usage; Sensor payload fabrication using both HgCdTe and silicon detectors made in-house; Both linear and two-dimensional array formats including readouts designed at SITP; and Formats as large as 512 × 1024.1 1 Paul Norton. 2009. Georgia Tech Trip to China and Korea. Santa Barbara.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays These activities, in addition to technical papers presented at various international conferences, indicate a major national effort with the intent to become a leading source of quality sensors, maybe even a dominant source. There was no report of extraordinary activity by China in the commoditized IR sensor markets; hence it is possible these activities will find primary use in military or intelligence missions. Close scrutiny of Chinese activities in high-yield, high-quality production of these sensors classes will determine whether China will soon become a major player in military detector technology. FINDING 5-1 An emerging foreign force in sensor technology is the set of newly established government-sponsored institutes in China. Extensive new laboratory facilities are known to be producing quality materials and sensor arrays. RECOMMENDATION 5-1 The intelligence community should closely monitor Chinese activities for signs that an operational capability is being established for manufacturing high-quality sensor arrays. Visible and IR sensor systems tend to vary significantly in the way they are applied in end products and also in their end customers. Visible sensors have a broad base of interest and a vast array of customers, ranging from the global civilian world (e.g., commercial, industrial, scientific, academic, and civilian government agencies) to the military and the intelligence community. Their broad application to civil uses is the primary driver for their development and represents the majority of their applications. An example would be proliferation of cell phones, especially in areas with less established landline telephone infrastructure than in the United States. These cell phones usually come with visible cameras. Alternatively, IR sensors have a much smaller application space, primarily either in national security applications or in specialized niche areas, such as scientific research, medicine, process control, and instrumentation. This smaller customer base results in a better-focused effort, but also a smaller and less diverse source of funding, principally from the government. FINDING 5-2 Visible sensor technologies are more strongly driven by commercial markets, especially overseas, than by national security requirements. In contrast, IR and thermal sensors are more strongly influenced by national security requirements. The differences between these widely varying applications and customers,
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays coupled to differences in the business and funding models, lead to differences in the signatures and key indicators of the visible and IR product lines. Below are examples of the way different factors have affected the research, development, and manufacture of sensor technologies. The examples could also provide some insight as to how these factors may shape the future of sensor technologies. Foreign governments have military-related activities under way to use sensor systems to provide intelligence, surveillance, and reconnaissance (ISR) information. Foreign governments also use sensor systems for internal law enforcement and civil concerns, such as pollution monitoring or tracking vehicular traffic. Among companies there is constant competition to be first to market. In contrast to lengthy government cycles, times for commercial sensor system technologies may be as short as six months or less, but seldom more than a few years. Also, commercial sales for some items can be larger than sales for the government.2 Even though commercial sales can exceed those for government, the life cycle from development to fielding to retirement may be a fraction of that for government systems. This ratio could result in commercial systems being backward-integrated into, or augmenting, government capabilities. In other words, commercial products may end up driving government products.3 Often unit-cost reductions are obtained as a result of economies of scale in the production of large numbers of sensors, such as cell phone cameras. However, a high-performance sensor system, which foreign governments might fly on aircraft or satellites, would be costly. For near-peer competitors of the United States, such as China or Russia, costs for what is deemed to be an essential national security sensor system would probably not be a major prohibition to its development and deployment. For other nations, however, such costs could be a major driver in deciding whether or not to develop and deploy a costly, high-performance sensor system. 2 One example from the FLIR Systems Inc. Annual Report for 2009, page 63, revenue from external customers (in million dollars). Year 2009 2008 2007 Government Systems 655 569 382 Commercial Systems 492 508 397 Note: For this data the term “Commercial Systems” represents sales by the Thermography division plus the Commercial Vision Systems division because FLIR is combining both divisions into a single Commercial Systems division in 2010 (page 2 of report). From http://files.shareholder.com/downloads/FLIR/913990835x0x353521/81C2AFD8-637C-4E0B-99CA-039BCCAB36A9/Form_10_K_typeset.pdf. Last accessed on May 24, 2010. 3 Consider that the time frame of 10-15 years represents only about one generation (at most, two generations) of technologies and systems in use by the U.S. military today. That same time frame may represent perhaps 5-30 generations of commercial technology. Contrast the military deployment cycle to the two- to three-year pace of Moore’s law shrinking of integrated circuits.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays The United States has long enjoyed relative dominance with respect to night operations due to its superior tactical IR sensors. This situation, however, is changing. As technology advances have occurred, from starlight goggles to cooled IR to uncooled microbridges, the result has been lower cost and wider use in areas such as law enforcement, environmental surveillance, border surveillance, and even sport hunting. Earlier-generation technology has diffused into the marketplace (as an example, a Google search on night vision goggles pulls up hundreds of competing commercial sources). The U.S. IR sensor industry has gradually transformed over the past two decades from Department of Defense (DOD) prime-contractor dominance controlling the marketplace, to smaller research and development establishments and commercial system suppliers having a larger share. Foreign defense companies have also begun to vertically integrate their system products. For example, Thales,4 in France, formed SOFRADIR,5 in 1986, to produce mercury cadmium telluride (MCT) detectors for insertion into tactical systems; SOFRADIR now produces QWIPs, and it acquired Electrophysics6 in the United States in 2008. Further, Finmeccanica,7 an Italian conglomerate, acquired the key U.S. tactical sensor supplier DRS Technologies in 2008.8 Fortunately these acquisitions involve North Atlantic Treaty Organizations (NATO) countries, and “firewalls” are set up to prevent the diffusion of classified work out of the United States. Nevertheless, this trend to foreign defense company ownership would seem to dilute the U.S. supremacy in tactical IR sensors. Strategic IR sensors with higher performance are closely controlled by security classification. Often, cues to progress can be obtained from knowledge of what is happening in research and development facilities, but actual system deployment requires production capability. Experimental demonstrations are not sufficient for integration into militarily useful sensor systems. Hence, the critical transition to industrial production becomes an important tip-off for closer inspection to signal an escalation of capability by a foreign power or a foreign-owned company. In contrast to IR sensors, visible sensor developments are historically more accessible. Detector elements, sensors, and readout devices can be commercially procured with good capability. System configurations (e.g., multispectral or hyperspectral) are generally application specific, and they may be classified since they depend on mission requirements. 4 For additional information on Thales, please see http://www.thalesgroup.com/. 5 For additional information on SOFRADIR, please see http://www.sofradir.com/. 6 For additional information on Electrophysics, please see http://www.electrophysics.com/. 7 For additional information on Fenmeccanica, please see http://www.finmeccanica.it/Holding/IT/index.sdo. 8 For additional information on DRS Technologies, please see http://www.drs.com/.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays FINDING 5-3 There is a significant difference in infrastructure requirements and development paths between “strategic” (low volume, high unit value and capability) and “commodity” (high volume, lower unit value and capability) sensors and systems. Commodity sensors tend to have short (i.e., months or a small number of years) life cycles and to be closely tied to short-term market requirements. Satellites, which contain some of the most costly, complex, and technically advanced imaging platforms known to man, demand the highest possible quality and capability from their sensor systems. Historically the domain of only the most technically advanced and prosperous governments, satellites are rapidly becoming the purview of commercial industry, primarily for communications and broadcast applications. Importantly, high-resolution commercial satellites, such as the GeoEye-1 with 41 cm resolution are challenging military capabilities. Not only does commercial satellite imaging technology represent capabilities on a par with military systems, but the market size for commercial applications is much larger as well. The end result is greater interest and concomitant diversity of manufacturers, leading to increased competition and greater research and development in these areas.9 FINDING 5-4 Lowering of barriers to commercial satellite systems is expanding the market for “strategic-class” imaging technology. The next decade will see greater investment in these capabilities. U.S. EXPORT RESTRICTIONS U.S. companies are constrained from passing controlled information to foreign interests by numerous regulations and laws, including the International Traffic in Arms Regulations (ITAR), which is managed by the Department of State, but governs DOD operations. ITAR is intended to control, or at a minimum maintain knowledge of, the spread and dissemination of technology to minimize or mitigate the threat that advanced technology could pose to U.S. national security interests. The threat can manifest itself in many ways, but the two primary areas of interest are use of U.S. technologies against the United States (i.e., adversaries having U.S. capabilities, or nearly so) and adversarial development of countermeasures to negate or mitigate the advantage of U.S. technologies (i.e., counters to U.S. systems). Unfortunately ITAR appears to have exacerbated some of these problems, not mitigated them. 9 See http://www.sciencedaily.com/releases/2009/05/090526183858.htm.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays For example, with respect to U.S. night vision technology, foreign capability—uncontrolled and at times unknown (to the United States)—has been growing and providing a wide array of technologies to numerous customers. When a nation limits export of technology, it reduces the size of that nation’s potential market and consequently the number of, and profit associated with, items that are sold. This has a direct impact by reducing potential benefit from manufacturing learning and economies of scale and also reducing incentives to improve or evolve new technologies. Reductions in profits reduce available capital and thereby diminish industry’s ability to invest in research and development. There could also be a stifling effect on basic research at academic institutions. The cascading effect ultimately leads to slowed rates of growth and innovation, generally supporting a trend to drive innovation overseas and possibly to slow U.S. enhancement of current technologies. Where foreign markets exist, U.S. manufacturers will seek to compete if they believe they can benefit. One way this may be reconciled with ITAR restrictions is through purchase and development of foreign-made sensors, therefore maintaining the ability to export the product. Consequently, investment that might be made in improving U.S. technologies is diverted into research and development for improving unrestricted foreign technologies. ITAR ultimately results in smaller market size and reduced international share for U.S. firms. In addition to consequences (e.g., with respect to night vision technology), the U.S. government is forced to provide a larger portion of funding for research and development. Aside from costing more, this also limits innovation because research and development will be focused almost exclusively on meeting DOD needs, making it more difficult to pursue high-risk, high-payoff avenues. The area in which ITAR restrictions are most significant is where there exists a large commercial market, as well as a military market. FINDING 5-5 Current export restrictions will continue to have a significant effect on development and maturation of detector technologies over the next decade. Numerous foreign countries are already developing their own technology base rather than utilizing U.S. technology and often will compete with U.S. technology. U.S. export restrictions are a primary driver creating this competition. U.S. companies invest significant resources in obtaining, funding, and exploiting foreign products so that they can compete in foreign markets without export restrictions. As highlighted in Box 5-1, control of sensitive technology was recently cited in the Quadrennial Defense Review that included Presidential direction for a “comprehensive review” to identify reforms in the current export system.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays BOX 5-1 Control of Defense-related Technologies The global economy has changed, with many countries now possessing advanced research, development, and manufacturing capabilities. Moreover, many advanced technologies are no longer developed predominantly for military applications with eventual transition to commercial uses, but follow the exact opposite course. Yet, in the name of controlling the technologies used in the production of advanced conventional weapons, our system continues to place checks on many that are widely available and remains designed to control such items as if Cold War economic and military-to-commercial models continued to apply. The U.S. export system itself poses a potential national security risk. Its structure is overly complicated, contains too many redundancies, and tries to protect too much. Today’s export control system encourages foreign customers to seek foreign suppliers and U.S. companies to seek foreign partners not subject to U.S. export controls. Furthermore, the U.S. government is not adequately focused on protecting those key technologies and items that should be protected and ensuring that potential adversaries do not obtain technical data crucial for the production of sophisticated weapons systems. These deficiencies can be solved only through fundamental reform. The President has therefore directed a comprehensive review tasked with identifying reforms to enhance U.S. national security, foreign policy, and economic security interests. Reform efforts must reflect an inherently interagency process as current export control authorities rest with other departments. Similarly, meaningful reforms will not be possible without congressional involvement throughout the process. The Department of Defense has a vital stake in fundamental reform of export controls and will work with our interagency partners and Congress to ensure that a new system fully addresses the threats that the United States will face in the future. SOURCE: 2010 Quadrennial Defense Review. http://www.defense.gov/qdr/. Last accessed on August 29, 2010. As reform efforts are considered, three issues should be taken into account: (1) technology export controls may encourage proliferation; (2) U.S. markets could be reduced due to export controls; and (3) U.S. manufacturers might make more use of foreign technologies as U.S. technology enhancement slows. Also, it would be useful to keep in mind that the overall goal of regulating the dissemination of technology should be to minimize the threat posed by new and emerging technologies.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays SUPPLY CHAIN BOTTLENECKS As new technologies develop there may be only limited ability to supply early adopters. Until sufficient production becomes available, bottlenecks could arise. When there exists a single-supplier bottleneck of key components, several problems as well as vulnerabilities arise: Failure of the single supplier can have significant deleterious effect on research, development, and manufacture of sensor technologies and systems. The single supplier is subject to natural disasters, intentional attacks, or coercion, each of which can have significant impacts on organizations that depend on single-supplier products. The single supplier may affect U.S. domestic efforts, but some foreign companies may pursue technologies different from the United States. It is conceivable that situations may arise in which U.S. research, development, and manufacture may be affected, while foreign efforts might not. There is considerable benefit to be gained by maintaining cognizance of these single-point suppliers as they emerge with new technologies and evolve with the technology base. In the United States, responsibility for supply chain issues in government programs falls to the system program office and prime contractor in a shared responsibility. Normally, the supply of piece parts from foreign or domestic suppliers is ensured by requiring at least two sources or by stockpiling parts. This is the guarantee against disruption of system operations or future deliveries. The DOD bureaucracy acknowledges this possible disruption and has established an office to monitor this issue. Most DOD ISR systems pay particular attention to key technologies that are the heart of the sensor system concept. Considerable attention has been paid to parts such as application-specific integrated circuits (ASICs) that increasingly are made in off-shore production facilities. Most of the silicon foundries are located off shore, with concerns about continuity of supply and security of classified chips. Establishment of a U.S. “trusted foundry” and increased use of FPGAs (field-programmable gate arrays), which can be system-configured in controlled fashion, have mitigated this worry. FINDING 5-6 Evolution of new technologies often generates single-supplier bottlenecks. These can have significant, though transient, impacts on research, development, and manufacturing.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays RECOMMENDATION 5-2 The intelligence community should be aware of the development and status of single-supplier bottlenecks. ADDITIONAL CONSIDERATIONS Identifying trends is complicated by many different factors involved in making a deployable sensor system. Important macro trends include (1) growth of foreign businesses selling first- and second-generation sensor systems for military and civilian applications and (2) roughly fixed rates of U.S. research and development for sensors, primarily sponsored by government. Much ancillary equipment, such as optics and electronics, can be produced by several nations. For second-generation and commodity sensors, the focal plane array (FPA) is a small part of the system cost and is a mass-produced competitive item. The trend is market driven. For high-value sensors that use cutting-edge sensor technology—with chip fabrication that is proprietary or classified, low in volume, derived from U.S. government research and development, and has special processing features—the trend is performance driven. As foreign businesses equip much of the world with night vision capability, the once-prominent U.S. lead fades. The trend is for foreign production to focus on large quantities of sensors to gain the cost advantage associated with increased yield. Similar statements can be made about visible active pixel sensors for cell phones, except that market motivation in this case is for consumer products. The trend for high-performance sensors, such as high-sensitivity charge-coupled devices (CCDs) and two-color, large-pixel-count MCTs, is different. These third-generation sensors are exclusively fabricated in the United States. No current foreign commercial business profit motive exists to drive the efforts; hence, a different motivation is involved. Certainly strategic-level satellite sensor systems constitute a foreign motivation, and the ~500 Chinese satellites could employ an advanced-performance type of sensor to advantage. Therefore, a general trend by the Chinese to fabricate advanced sensor types is anticipated. This is supported by advanced research and development laboratories, particularly for MCT and single-layer superlattice (SLS) structures. Reports of heightened laboratory investment in Wuhan support this conclusion (see prior discussion). Although detectors and sensors may have considerable capability, this may not be fully exploited due to limitations in other portions of the system. For example, given the existence of high-resolution, broad-band imagers, the data throughput needed to successfully exploit their full capabilities may not exist (see discussion in Chapter 4). Although much of this report addresses technology developments directly related to detectors and sensors, they must be integrated into an overall system. To
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays make these technologies viable, a vast array of support, interface, and associated technologies must also mature and be integrated into a functional system. In many cases the limiting factor of a capability is not the detector or sensor technology but rather an ancillary technology. For example, a sensor may work effectively and with great capability in a laboratory, but because of the large amount of data generated it may be unable to function effectively in a system due to cooling or electronic limitations. Further, even without such limitations, other problems (e.g., manufacturability, usability, and sustainability in the field) could conspire to limit ultimate system effectiveness. Consider the problem of replacing 100,000 military night vision systems. Even though a generational leap in technology may be available now, it may take many years to obtain funding and put in place a supply chain sufficient to replace the system worldwide. CONCLUDING THOUGHTS The ability of the U.S. military to operate at night is no longer unique: Focused foreign investment and the reluctance of the United States to share leading-edge technology with allied nations have resulted in the proliferation of sensor-system component manufacturing to Europe and Israel with equivalent levels of performance. To offset costs associated with maintaining high-technology detector production, U.S. allies have exported critical components and technology because diplomacy does not always trump economic incentive. Thus, the technology is migrating to Asia, where American influence has little bearing on export control. From the U.S. perspective, two principal threats from the proliferation of imaging sensor systems are (1) organizations that resort to clever application of available technology—for example, improvised explosive devices—and (2) developed countries with imaging systems that approach parity with the United States. The difference in threat level between some night vision capability and none is more significant than the difference between first- and third-generation imaging IR systems. As low-cost thermal imagers become more readily available, such as in some luxury automobiles, it remains only a matter of time before the U.S. military faces adversaries with IR rifle scopes and even night sights for man-portable missile launchers on current battlefields. This technology escalation should come as no surprise, and continued U.S. research and development of sensors and technologies to detect and counter such threats will be increasingly significant. Persistent surveillance is emerging as the centerpiece of network-centric warfare for the asymmetric engagements the United States has encountered in Afghanistan and Iraq. The United States hopes to become the omnipresent “eye-in-the-sky” and continuously monitor everything of interest. The United States now has the
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays capability of doing this in daylight, but the mountains of data that are generated to survey a relatively small area require significant resources to generate actionable information. As larger-format IR sensors become more readily available, persistent surveillance will quickly become a data bandwidth and signal-processing nightmare and will not be truly practical without significant innovations in autonomous signal processing, video compression, and low-power, high-data-rate, radio-frequency links. With the current focus on the Mideast, it is easy to ignore the potential threat of more sophisticated sensor technology from the developed nations. Here, any technology advantage the United States may have once enjoyed has eroded to the point where the warfighters are essentially at parity. The deployment of third-generation IR sensor technology will provide some level of overmatch for the user, but gaining a significant operational advantage will mandate the development of a new generation of active or passive IR sensors that provide the user with higher-resolution imagery at longer standoff range through FPAs with gain, advanced signal processing, and covert illumination sources. In addition to the United States, the French (SOFRADIR), the Germans (AIM), and the United Kingdom (SELEX) are investing in the development of sensors based on detectors with “noiseless” gain that can amplify low-intensity signals to overcome system noise limits at wavelengths ranging from 1 μm through the long-wavelength infrared (LWIR). In conjunction with new solid-state laser illumination sources and recent developments in silicon complementary metal oxide semiconductor (CMOS) electronics, these prototype systems can provide three-dimensional images that significantly enhance identification capability and can employ time of flight to eliminate background at ranges other than the target. Examples of a range of competitive foreign detector technologies are shown in Tables 5-1 and 5-2. TABLE 5-1 Competitive Non-U.S. Cryogenic IR Sensor Technology Country Company MCT InSb Superlattice SWIR Optical Materials China Various LPE/MBE R&D ? Dominant position France SOFRADIR LPE/MBE R&D InGaAs R&D Germany AIM/Fraunhofer LPE/MBE Production MCT R&D Israel SCD LPE Dominant position R&D ? R&D Japan Various LPE/MBE ? InGaAs Dominant position Russia Various Bulk/LPE Small arrays Theory ? Dominant position United Kingdom SELEX LPE/MOCVD InGaAs R&D NOTE: LPE = liquid-phase epitaxy; MBE = molecular beam epitaxy; MOCVD = molecular organic chemical vapor deposition.
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays TABLE 5-2 Competitive Non-U.S. Uncooled IR FPA Technology Country Company Microbolometers MWIR China Alpha Si MCT R&D Germany AIM/Fraunhofer ? MCT R&D Israel SCD VOx nBn R&D Various Buy French MCT R&D France SOFRADIR Japan Various Si diodes ? Russia Buy French ? MCT R&D United Kingdom SELEX Buy ? MCT R&D Gains in sensor performance and cost reduction can be attributed to advances in detector materials and devices and silicon CMOS technology. The commercial investment in CMOS has resulted in “smarter” FPAs and more capable signal processors. State-of-the-art CMOS technology is readily available worldwide and has certainly contributed to leveling the playing field for both consumer and military electronics. Custom integrated circuits, such as for FPA readouts, can be fabricated in any number of foundries, so performance and functionality are only constrained by the talent of the designer. Imaging systems will continue to deliver improvements in resolution and provide coverage of larger areas. The fundamental limits to sensitivity for passive broadband, Earth-viewing sensors are being approached. Leap-ahead sensor capabilities could occur related to active systems, where sensors will incorporate illumination sources that enable new imaging modes that enhance recognition range by generating three-dimensional renditions of a scene. An additional example could be non-imaging sensors, where spectral and temporal signatures will enable identification of specific materials within a given field of view. Also, it is anticipated that a large gain in surveillance capability will come from parallel signal processing and improved video compression for data transmission. The globalization of state-of-the-art CMOS foundries and production capabilities will tend to level the playing field for semiconductor electronics. The ability to develop semiconductor technology is no longer restricted to Western high-technology centers as is evidenced by the number of non-U.S. graduate students enrolled in world-class graduate science and engineering programs. As a result of this trend in globalization, sensor proliferation will accelerate; U.S. ability to maintain a leadership technology position will require more focus with shorter development cycles. The evolution of low-cost reliable coolers will facilitate higher-performance sensor systems. Already, this trend is being seen in some hand-held soldier systems
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays where the cooler and FPA cost-power trades render this solution more acceptable than larger-aperture, uncooled imagers. A new generation of minicoolers is becoming available and, with the emergence of higher-operating-temperature detector technology, could supplant the move to uncooled thermal sensors. As manufacturing costs continue to fall, commercialization of imaging sensors will make less capable night vision technology more readily available in the marketplace. Subsequently, nonaligned adversaries will adapt these sensors to low-cost weapons systems. Advanced processors, such as those available in video games, are being adapted to sensor image processing tasks; it no longer requires an expensive, custom real-time processor to sift video data, and knowledgeable engineers are also becoming available globally. Tracking Developments How does one track sensor development, and what does one look for? Generally, observers fail to recognize breakthrough technologies when they are featured at a technical conference, show up in a journal article, or are touted by some start-up on a website. Generally, few of these innovations will survive the journey to market and, on occasion, a promising new technical development will be kept under wraps. For asymmetric engagements, low-cost commercial products, creative talent, and black-market availability will determine the sophistication of sensor systems. These can be tracked, and engineering tiger teams can postulate the possibilities of employing a BMW forward-looking infrared (FLIR) as a night site for a crew-served weapon or a man-portable missile launcher and ways to detect and counter such weapons systems. Innovative commercial cameras with autofocus or image stabilization technology may lend themselves to the development of low-end drones. The United States must be prepared for surprise and respond quickly to neutralize any short-term advantage presented by our adversaries. Silicon CMOS technology is the manufacturing platform upon which most modern sensors are based, from readout integrated circuits to sophisticated signal processors. State-of-the-art CMOS is globally available and makes establishment of a significant advantage in sensor technology potentially short-lived. The developments that should be tracked include the heterogeneous integration of other technologies onto the CMOS platform. Examples include the incorporation of germanium into the CMOS platform for higher-speed electronics and for detectors and microelectromechanical (MEMs) devices for accelerometers or uncooled microbolometer-based thermal detectors. The integration of compound semiconductors with CMOS creates the potential for monolithic FPAs that span the entire electromagnetic spectrum. As the technology continues to evolve, one could envision FPAs with integral signal
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Seeing Photons: Progress and Limits of Visible and Infrared Sensor Arrays processors that are layered into the CMOS chip. Here, only specified intelligence would be the output, significantly reducing the data bandwidth for the sensor. As heterogeneous integration becomes a manufacturing reality, the developers of this technology will need to be monitored to avoid surprise at its initial introduction into sensor systems.