Margaret Kohin

Performance limits of uncooled VOx microbolometer focal plane arrays

Uncooled microbolometer technology has shown dramatic improvements in recent years as tens of thousands of imaging systems have been delivered. This paper outlines the performance limits that must be overcome to continue to achieve performance improvements.

More applications of uncooled microbolometer sensors

Lockheed Martin IR Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on microbolometer technology, a silicon micromachined sensor that combines wafer level silicon processing with a device structure capable of yielding excellent imaging performance. Here, in the first of a series of papers, we report on several applications that are utilizing the Lockheed Martin microbolometer sensor. The performance of our basic uncooled sensor has been measured (and reported in multiple papers) to determine sensor capabilities for insertion into both military and commercial products. Non-linearity of the sensor over a scene temperature range of 95 degrees Celsius is less than 0.5%. Our sensors typically have temporal NETDs of less than 70 mK as well as spatial NETDs of less than 50 mK. MRTD performance is less than 0.4 degrees Celsius at spatial frequencies more than 20% beyond Nyquist. Spatial noise variation over time has been measured and found to meet both commercial and military requirements with excellent spatial noise over wide scene and ambient temperature ranges. Some of the multiple applications in which our uncooled sensors have been used have just recently been described in one report demonstrating the varied and unique uses of this product. Our sensor is now used by dozens of partners and customers for applications ranging from hand-held radiometric cameras to driving aids; from drivers aids to miniature cameras from rifle sights to radiometers. These applications will be discussed along with their unique system level performance parameters. Video will be used to demonstrate the various applications discussed.

Recent improvements and developments in uncooled systems at BAE SYSTEMS North America

BAE SYSTEMS has designed and developed MicroIR microbolometer focal plane arrays (FPAs) in three formats (160x120, 320x240, and 640x480) and with two different pixel sizes (46micrometers and 28micrometers ). In addition to successfully demonstrating these FPA technologies, BAE SYSTEMS has produced and delivered thousands of 320x240 (46micrometers pixel) imaging modules and camera cores for military, thermography, firefighting, security and numerous other applications throughout the world. Recently, BAE SYSTEMS has started production deliveries of 160x120 (46micrometers ) systems, demonstrated 320x240 and 640x480 second-generation (28micrometers ) imaging, and demonstrated second-generation thermoelectric cooler-less operation. This paper discusses these recent accomplishments and, when possible, provides quantitative NETD and performance data for our newly developed FPAs and systems. Video will be shown to demonstrate sensor performance capabilities.

Uncooled infrared sensors for surveillance and law enforcement applications

Uncooled infrared imaging technology provides a new, affordable, high performance tool for both conventional and emerging applications in the surveillance and law enforcement markets. This technology offers users significant advantages, including high reliability, low power consumption, excellent image clarity, and good performance in adverse environments. This paper briefly discusses the various technologies used for night imaging, the advantages that infrared systems offer law enforcement and surveillance applications, how uncooled infrared systems fit into this market, and the status of uncooled microbolometer systems at Lockheed Martin.

Recent developments in uncooled IR technology

Sanders IR Imaging Systems (IRIS), a Lockheed Martin Company, has made recent improvements in high performance uncooled IR focal plane arrays and systems. This paper provides performance results for three of these new FPAs and systems. First we discuss a new 320 X 240, 46 micrometer pitch FPA, which when put into a system with a transmission of 74%, will provide a system NETD of < 26 mK (F/0.8, 60 Hz). This FPA has a power of < 250 mW (which includes on-chip 14 bit analog to digital conversion), and virtually no crosstalk from saturation. Second, we discuss the first ever 640 X 480 element uncooled IR camera. This camera, which is based on a 28 micrometer pitch microbolometer staring FPA, produces a system sensitivity of < 150 mK, (F/1, 30 Hz) and has a Minimum Resolvable Temperature Difference of < 0.4 degrees Celsius at the Nyquist frequency. Finally, we have developed a new lightweight thermal weapons sight (TWS). Our TWS, which weighs < 3 lbs. (with battery) and operates over the -37 degrees Celsius to +49 degrees Celsius temperature range, has demonstrated a boresight retention of < 0.2 mrad after 1000s of rounds were fired.

Commercialization of uncooled infrared technology

BAE Systems is the leading producer of uncooled microbolometer based thermal imaging engines in the world. Initial investments to develop and produce uncooled infrared (IR) technology were primarily driven by military applications, but it was the commercial market with the potential for large product volumes which provided BAE Systems with the business model required for investment in uncooled IR technology. This paper reviews the heritage of BAE Systems technology and current products and is an example of the success of a Dual-Use technology area which DARPA invested in during the 1990s.

Even more applications of uncooled microbolometer sensors

Lockheed Martin IR Imaging Systems is developing low cost, high performance, uncooled IR imaging products for both military and commercial applications. These products are based on microbolometer technology, a silicon micromachined sensor that combines wafer level silicon processing with a device structure capable of yielding excellent imaging performance. Here, in the third of a series of papers, we report on several applications that are utilizing the Lockheed Martin microbolometer sensor. The performance of our basic uncooled sensor has been measured to determine sensor capabilities for insertion into both military and commercial products. Non-linearity of the sensor over a scene temperature range of 95 degrees C is less than 0.5 percent. Our sensor typically have temporal NETDs of less than 70 mK as well as spatial NETDs of less than 50 mK, with an instantaneous dynamic range of 84 dB, and a total dynamic range of 120 dB. MRTD performance is less than 0.4 degrees C at spatial frequencies more than 20 percent beyond Nyquist. Spatial noise variation over time has been measured and found to meet both commercial and military requirements with excellent spatial noise over wide scene and ambient temperature ranges. Some of the multiple applications in which our uncooled sensor have been used have been described in reports demonstrating the varied and unique uses of this product. Our sensor is now used by dozens of partners and customers for applications ranging from hand-held radiometric camera to driving aids; from long range surveillance cameras to miniature cameras; from rifle sights to helmet mounted camera. These applications will be discussed along with their unique system level performance parameters. Video will be used to demonstrate the various applications discussed.

Technology and application advancements of uncooled imagers

Having delivered over 30,000 uncooled microbolometer based thermal imaging engines, BAE Systems is the worlds leading producer. Advancements in technology include the demonstration of broadband microbolometers on a 46 μm pixel pitch which have excellent sensitivity in the MWIR (NETD ≈180 mK, 3-5 μm) and LWIR (NETD ≈ 15 mK, 8-12 μm) wavebands. Application advancements include the development of a family of thermal weapons sights for the military which will replace current cooled systems with lighter, lower power systems and the introduction of a new generation of handheld and pole mounted thermal imagers for commercial markets.

Developments in uncooled IR technology at BAE SYSTEMS

Uncooled microbolometer thermal imaging sensor technology has begun to successfully address military, government and commercial applications in the real world. BAE SYSTEMS, located in Lexington MA, has been involved in the design and development of uncooled IR technology since the early 1980s. Our current MicroIRTM products are based on vanadium oxide (VOx) microbolometers. Thousands of uncooled microbolometer thermal imaging sensors are now being produced and sold annually. A the same time, applied research and development on the technology continues to improve the basic products and make them suitable for new applications. In this paper we report on the status and improvements achieved in the MicroIRTM product line, based on 320 X 240 element and 160 X 120 element FPAs with 46 μm pixel pitch. Other near term MicroIRTM products include 320 X 240 and 640 X 480 FPAs with 28 micrometers pixel pitch and measured sensitivities below 50 mK. In the systems area we discuss development and testing of a Light Thermal Weapon Sight (LTWS) for the U.S. Army, being developed by BAE SYSTEMS in partnership with Thales, based upon our uncooled MicroIRTM focal plane arrays (FPA) and systems. The LTWS prototypes were based upon our Standard Imaging Module SIM200, which employs our LAM2C, 320 X 240 element, microbolometer FPA. Finally we discuss the 480 X 640 element FPA and its application to the Heavy Thermal Weapon Sight application.

Quantitative and imaging performance of uncooled microbolometer sensors

Lockheed Martin IR Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on the microbolometer technology, a silicon micromachined sensor that combines wafer level silicon processing with a device structure capable of yielding excellent imaging performance. Here we report on the latest technical improvements and performance of an uncooled sensor as measured through laboratory and field testing. The performance of our uncooled sensor has been measured to determine sensor capabilities for insertion into both military and commercial products. Linearity of the sensor over a scene temperature range of 95 degrees Celsius is less than 0.5%. Our sensors typically have temporal NETDs of less than 70 mK as well as spatial NETDs of less than 50 mK. MRTD performance is less than 0.4 degrees Celsius at spatial frequencies more than 20% beyond Nyquist. Sensor stability over time has been measured and found to meet both commercial and military requirements. Spatial noise over a wide scene temperature range is reported as well as other test results. Video is used to demonstrate sensor performance capabilities in a variety of applications.