Uncooled thermal imaging sensor and application advances

Norton, Paul; Cox, Stephen K.; Murphy, Bob; Grealish, Kevin; Joswick, Mike; Denley, Brian; Feda, Frank; Elmali, Loriann; Kohin, Margaret

doi:10.1117/12.667762

Cited by 7 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(11)(12)(13)(14)(15)(16)(17)(18) The a-Si is more easily dominated by 1/f noise but it is also operated typically at 4-5 volts where the VOx is at typically 2-2.5 volts.…”

Section: Relative Strengths Of Noise Sourcesmentioning

confidence: 99%

Microbolometer sensor model for performance predictions and real-time image generation of infrared scenes and targets

et al. 2008

View full text Add to dashboard Cite

Presented is a comprehensive, physics-based model for microbolometer detector and sensor performance prediction. The model combines equations found in the literature and various standard models that generate NETD, MRTD, 3-D noise statistics and atmosphere characteristics (MODTRAN-based), with a comprehensive microbolometer model and HgCdTe model developed by the author to provide an end-to-end detector/FPA/sensor analysis and design tool, as well as a realistic image sequence generation tool. The model characterizes the individual pixel element based on the structure used, the various layer thicknesses, the electrical and thermal characteristics of the bolometer material and the biasing and readout circuit, and uses these results to calculate response and noise, NEP and NETD. The NETD, MTF and MRTD are predicted from the optics, detector and readout. Predicted NETD has been compared and verified with values found in literature, results from other models, and to uncooled camera measurements. The MRTD prediction has been verified with camera measurements and with standard industry MRTD model outputs. The model also calculates atmospheric path radiance and transmittance for horizontal paths based on MODTRAN outputs for the LWIR band at altitudes from 0 to 10km and ranges from 1 to 50km for assessments of air-to-air engagement SNR's. The model in matlab utililizes a 3-D noise model to provide accurate realistic imagery used to present realistic sensor images and to further validate the NETD and MRTD routines.(1) Images at 30Hz and 60Hz have been generated for visual assessment by the user and have mirrored industry model results and real-time camera images for MRTD's for the temporal noise case. The model's 3-D noise generation feature allows the prediction of MRTD vs. frequency under any 3-D noise combination. This model provides an end-to-end performance prediction tool useful in bolometer element design, readout design and for system level trade studies.

show abstract

“…(11)(12)(13)(14)(15)(16)(17)(18) The a-Si is more easily dominated by 1/f noise but it is also operated typically at 4-5 volts where the VOx is at typically 2-2.5 volts.…”

Section: Relative Strengths Of Noise Sourcesmentioning

confidence: 99%

Microbolometer sensor model for performance predictions and real-time image generation of infrared scenes and targets

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Figure 4 is an example SEM of foundry-processed bolometer with leg widths of <0.0.2 μm for single-level and multi-level designs. [7][8][9] There is, however, a significant design and process challenge for microbolometer designs <17 μm. Specifically, with as much as a 15× to 25× reduction in pixel area from the initial 50-μm designs, there is a proportional increase in NETD (Sec.…”

Section: Limiting Factors For Performance Of Smallmentioning

confidence: 99%

Uncooled long-wave infrared small pixel focal plane array and system challenges

et al. 2013

View full text Add to dashboard Cite

Abstract. There is a strong motivation for smaller pixels based on enduser demand for lower-cost, higher-resolution camera systems both for military and commercial applications. Uncooled detector technology fits the need for a low size, weight, and power system. We explore the tradeoffs and challenges to achieving pixel designs smaller than the current 17-μm state-of-the-art detectors without loss in sensitivity or resolution. For illustration we consider a 12-μm design. We also address modulation transfer function issues as the pixel size shrinks, and examine the difference between the performance of present devices and the theoretical performance limit for uncooled detectors. IntroductionFifteen to 20 years ago, developments in the semiconductor industry enabled the earlier generations of uncooled focal plane array (FPAs) and cameras with small format, 160 by 120 and then 320 by 240 array sizes with large pixels, generally in the neighborhood of 50 × 50 μm 2 . The detector material was usually vanadium oxide (VOx), alpha-silicon (a-Si) or ferroelectrics. The wave band over which the optics and detectors of a camera were generally designed to receive and respond to radiation that is approximately 7.5 AE .0.5 μm 2 to 13 AE 1 μm 2 . The user community, mainly the military at that time, specified camera operational requirements, which were typically around a 50-mK noise equivalent temperature difference (NETD), a frame rate of 30 Hz, and commensurate time constants for applications such as a thermal weapons sight or helmet-mounted goggles. The sensitivity of the detectors was far from the fundamental limits and thus drove the need for optics with an F/number near 1.0 to obtain the desired NETD. The modulation transfer function (MTF) of the system was almost never dominated by the MTF of the optics. Over the years, the semiconductor industry has made advances with ever smaller design rules, enabling the uncooled camera manufacturers to further push their designs and performance. Pixel sizes have been reduced from 50 to ∼25 μm, then to 17 μm, and today uncooled camera manufacturers are looking into developing FPAs with pixels in the range of 10 to 13 μm while also increasing the resolution of the arrays to a nominal 1 K × 1 K format.1,2 The user-desired operational specifications generally require a 35-to 50-mK NETD and a 10-to 12-ms time constant with a frame rate of 30 or 60 Hz. A nominal F/1 optic is still required to obtain this sensitivity. There is also interest in further shortening the time constant to 5 ms or less while maintaining good NETD performance for higher speed motion applications. This raises a number of considerations, practical and theoretical, related to the benefits of making uncooled detector pixels much smaller than 17 μm. This paper explores some of those considerations.

show abstract

IR Imaging

Kimata

2024

Reference Module in Materials Science and Materials Engineering

View full text Add to dashboard Cite

Uncooled thermal imaging sensor and application advances

Cited by 7 publications

References 0 publications

Microbolometer sensor model for performance predictions and real-time image generation of infrared scenes and targets

Microbolometer sensor model for performance predictions and real-time image generation of infrared scenes and targets

Uncooled long-wave infrared small pixel focal plane array and system challenges

IR Imaging

Contact Info

Product

Resources

About