Advancements in uncooled microbolometer technology over the last several years have opened up many commercial
applications which had been previously cost prohibitive. Thermal technology is no longer limited to the military and
government market segments. One type of thermal sensor with low NETD which is available in the commercial market
segment is the uncooled amorphous silicon (α-Si) microbolometer image sensor. Typical thermal security cameras focus
on providing the best image quality by auto tonemaping (contrast enhancing) the image, which provides the best contrast
depending on the temperature range of the scene. While this may provide enough information to detect objects and
activities, there are further benefits of being able to estimate the actual object temperatures in a scene. This
thermographic ability can provide functionality beyond typical security cameras by being able to monitor processes.
Example applications of thermography<sup></sup> with thermal camera include: monitoring electrical circuits, industrial
machinery, building thermal leaks, oil/gas pipelines, power substations, etc...<sup></sup> This paper discusses the methodology
of estimating object temperatures by characterizing/calibrating different components inside a thermal camera utilizing an
uncooled amorphous silicon microbolometer image sensor. Plots of system performance across camera operating
temperatures will be shown.
This paper provides results from testing and analysis of sun exposure effects on amorphous silicon (α-Si)
microbolometers and vanadium oxide (VOX) microbolometers. Gain and offset changes for each detector
type is provided. Results from different sun exposure levels corresponding to different geographic locations
and time of year are presented. Data associated with increasing exposure duration and number of exposures
is presented. The time constants associated with the sun exposure effects are also provided. Potential
mitigation processes and algorithms are explored reducing the impact on image quality. The effectiveness of
mitigation processes and algorithms is presented.
This paper is a follow-up to the paper presented at SPIE Electronic Imaging Science and Technology in San Jose, 2007,
"Characterization and system modeling of a 5-Mpixel CMOS array."
We expand and refined test methodologies used in the characterization and selection process of CMOS arrays targeting megapixel security camera applications. This paper presents work in the following areas: system gain, gain noise, binning noise, F-number response, system modeling, and temperature effects. Since security cameras must operate under harsh temperature extremes, performance under these conditions must be understood. Characterizations are made for the following areas: dark current, DSNU, hot pixels, clusters, temporal noise and spatial noise.
We present characterization results for a 5 million pixel CMOS image sensor designed for high speed applications. This sensor is capable of outputting 14 frames per second and incorporates on-chip 12-bit digitization. We present measurements of system gain, read noise, dark current, charge capacity, linearity, photo response non-uniformity, defects, and quantum efficiency. The image sensor incorporates exposure control functionality, windowing, on-chip binning, anti-blooming capability and rolling shutter architecture to implement image capture mode. The results show a favorable aspect of the ability to achieve high speed, high resolution, and very good sensitivity in a monolithic CMOS sensor. Architecture trades for high speed imaging systems utilizing CCDs and CMOS sensors are also presented.
The capabilities and performance of focal plane subsystems used in astronomical space telescopes have increased significantly over the last 45 years. Significant gains have been made in format size, sensitivity, and spectral range coverage. This paper outlines the history of UV, visible, and IR astronomy missions occurring over this time period and describes the focal planes used. We also discuss the progression of the associated detector and focal plane technology during this timeframe.
Although there have been significant gains over the last 45 years, there is still both the promise and need for continued improvement. Several missions over the next few years will use new and innovative technologies. In this paper, we describe upcoming missions and how technological breakthroughs in detectors, focal plane packaging, and readout electronics will extend the reach of science. Finally, we conclude by describing how these technologies will mature over the next 10 years.
The NIRCam instrument will fly ten of Rockwell Scientific’s infrared molecular beam epitaxy HgCdTe 2048x2048 element detector arrays, each the largest available with current technology, for a total of 40 Megapixels. The instrument will have two varieties of MBE HgCdTe, a SWIR detector with λ<sub>co</sub> = 2.5 μm, for the shortwave channel of NIRCam (0.6-2.3 μm); and a MWIR detector with λ<sub>co</sub> = 5.3 μm, for the longwave channel of NIRCam (2.4-5.0 μm). Demonstrated mean detector dark currents less than 0.01 electrons per second per pixel at operating temperatures below 42 K for the MWIR and below 80 K for the SWIR, combined with quantum efficiency in excess of 80 percent and read noise below 6 electrons rms, make these detector arrays by far the most sensitive SWIR and MWIR devices in the world today. The unique advantages of molecular beam epitaxy as well as FPA data on noise, dark current, quantum efficiency, and other performance metrics will be discussed. In addition, the focal plane assembly package designs will be presented and discussed.
The primary mission of the upcoming HiRISE instrument on the Mars Reconnaissance Orbiter spacecraft is to better
understand the geologic and climatic processes on Mars and to evaluate future landing sites. To accomplish this goal, a high resolution space-based camera is being developed that employs a 0.5m aperture Cassegrain-type telescope coupled to a large focal plane array (FPA) measuring approximately 14" (L) x 2" (W) x 2" (D). The FPA is populated with 14 time delay and integrate (TDI) format custom charge-coupled device (CCD)-based detectors. The FPA includes
panchromatic, near infrared, and blue-green spectral channels. The panchromatic channel has 20,000 pixels in the cross track direction. Each color channel consists of 4,000 pixels in the cross track direction. The minimum ground sampling distance of all channels is 50 cm per pixel. The instrument’s instantaneous field of view is 1.43o x 0.1o. Over the 5-year mission, the FPA will map a portion of the surface of Mars with high spatial resolution and high signal-to-noise
ratio (>100:1 at all latitudes). Electronics are housed immediately behind the FPA, which yields a low noise, compact
design that is both robust and fault tolerant. Test and characterization data from the FPA and custom CCD-based detectors is discussed along with the results from performance models.
The space telescope imaging spectrograph (STIS) was designed as a versatile spectrograph capable of maintaining or exceeding the spectroscopic capabilities of both the Goddard High Resolution Spectrograph and the Faint Object Spectrograph (FOS) over the broad bandpass extending from the UV through the visible. STIS achieves performance gains over the aforementioned first generation Hubble Space Telescope instruments primarily through the use of large a real detectors in both the UV and visible regions of the spectrum. Simultaneous spatial and spectral coverage is provided through long slit or slitless spectroscopy. This paper will review the detector design and in-flight performance. Attention will be focussed on the key issue of S/N performance. Spectra obtained during the first few months of operation, illustrate that high signal-to-noise spectra can be obtained while exploiting STIS's multiplexing advantage. From analysis of a single spectrum of GD153, with counting statistics of approximately 165, a S/N of approximately 130 is achieved per spectral resolution element in the FUV. In the NUV a single spectrum of GRW + 70D5824, with counting statistics of approximately 200, yields a S/N of approximately 150 per spectral resolution element. An even higher S/N capability is illustrated through the use of the fixed pattern split slits in the medium resolution echelle modes where observations of BD28D42 yield a signal-to-noise of approximately 250 and approximately 350 per spectral resolution element in the FUV and NUV respectively.
The STIS instrument was installed into HST in February 1997 during the Servicing Mission 2. It has almost completed checkout and is beginning its science program, and is working well. Several scientific demonstration observations were taken to illustrate some of the range of scientific uses and modes of observation of STIS.
The space telescope imaging spectrograph (STIS) is currently being developed for in-orbit installation onto the Hubble Space Telescope in 1997, where it will cover the wavelength range from 115 to 1000 nm in a variety of spectroscopic and imaging modes. For coverage of the 305 - 1000 nm region (and backup of the 165 - 305 nm) region, STIS will employ a custom CCD detector which has been developed at Scientific Imaging Technologies (SITe; formerly Tektronix CCD Products Group). This backside-illuminated device incorporates a proprietary SITe backside treatment and anti-reflective coating to extend the useful quantum efficiency shortward of 200 nm. It also features low noise amplifiers, multi-pinned-phase implants, mini-channel implants, and four quadrant readout. The CCD is thermo-electrically cooled to an operating temperature of -80 degree(s)C within a sealed, evacuated housing with its exterior at room temperature to minimize the condensation of absorbing contaminants in orbit. It is coupled to a set of low noise, flexible, fault-tolerant electronics. Both housing and electronics are being developed by the STIS prime contractor, Ball Aerospace & Communications Group. We describe here the design features, performance, and fabrication status of the STIS CCD and its associated subsystem, along with results of radiation testing.
High Energy, Optical, and Infrared Detectors for Astronomy IV
27 June 2010 | San Diego, California, United States
High Energy, Optical, and Infrared Detectors for Astronomy
23 June 2008 | Marseille, France
High Energy, Optical, and Infrared Detectors for Astronomy II
24 May 2006 | Orlando, Florida , United States
SC1079: CMOS Image Sensor Architecture and Design for Scientific and Space Applications
This course provides attendees with an intermediate knowledge of CMOS image sensors and cameras for demanding applications including extremely low light levels, wide scene dynamic range, or harsh environmental conditions (high temperature, radiation exposure, etc.). The course describes recent advances in sensor and pixel architectures as well as the associated processing and software algorithms to achieve the required performance. The course provides examples of high performance image sensors along with the architectures, designs and technologies required to realize them. The current state-of-the-art of the technology is reviewed with a look at areas of research and trends.
SC905: CMOS Imaging Sensor Architecture, Construction, and Applications
This course provides a review of CMOS imager technologies looking at architectures, designs, and applications. Performance differences between different types of CMOS imaging arrays (3T, 4T, 5T, and 6T) are covered. CMOS imager architectures for the pixel design and readout circuitry are presented along with fundamental performance limitations and tradeoffs associated with each configuration. Pixel design layouts and physical stacks are shown for 3T, 4T, 5T, and 6T along with performance impacts associated with layout configurations. Different configurations of readout multiplexers are shown along with associated noise, speed, power, accuracy, and features. System applications are discussed along with system impacts associated with different sensor architectures. The current status of the technology is reviewed with a look at future research and development trends.