This paper overviews the history of infrared detector materials starting with Herschel’s experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940’s. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ∼3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called “dual-use technology applications.” One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

https://web.xidian.edu.cn/bjwang/files/20140924_180458.pdf

History of infrared detectors

. The Orbiting Carbon Observatory-2 (OCO-2) carries and points a three-channel imaging grating spectrometer designed to collect high-resolution, co-boresighted spectra of reflected sunlight within the molecular oxygen (O2) A-band at 0.765 microns and the carbon dioxide (CO2) bands at 1.61 and 2.06 microns. These measurements are calibrated and then combined into soundings that are analyzed to retrieve spatially resolved estimates of the column-averaged CO2 dry-air mole fraction, XCO2. Variations of XCO2 in space and time are then analyzed in the context of the atmospheric transport to quantify surface sources and sinks of CO2. This is a particularly challenging remote-sensing observation because all but the largest emission sources and natural absorbers produce only small ( To meet its demanding measurement requirements, each OCO-2 spectrometer channel collects 24 spectra s−1 across a narrow (  17 000), dynamic range (∼ 104), and sensitivity (continuum signal-to-noise ratio > 400). The OCO-2 instrument performance was extensively characterized and calibrated prior to launch. In general, the instrument has performed as expected during its first 18 months in orbit. However, ongoing calibration and science analysis activities have revealed a number of subtle radiometric and spectroscopic challenges that affect the yield and quality of the OCO-2 data products. These issues include increased numbers of bad pixels, transient artifacts introduced by cosmic rays, radiance discontinuities for spatially non-uniform scenes, a misunderstanding of the instrument polarization orientation, and time-dependent changes in the throughput of the oxygen A-band channel. Here, we describe the OCO-2 instrument, its data products, and its on-orbit performance. We then summarize calibration challenges encountered during its first 18 months in orbit and the methods used to mitigate their impact on the calibrated radiance spectra distributed to the science community.

/pdf/the-on-orbit-performance-of-the-orbiting-carbon-observatory-22fijzo79j.pdf

The on-orbit performance of the Orbiting Carbon Observatory-2 (OCO-2) instrument and its radiometrically calibrated products

This article presents a review on the current status, challenges, and potential future development opportunities for HgCdTe infrared materials and detectortechnology. A brief history of HgCdTe infrared technology is firstly summarized and discussed, leading to the conclusion that HgCdTe-based infrared detectors will continue to be a core infrared technology with expanded capabilities in the future due to a unique combination of its favourable properties. Recent progress and the current status of HgCdTe infrared technology are reviewed, including material growth,device architecture, device processing, surface passivation, and focal plane array applications. The further development of infrared applications requires that future infrared detectors have the features of lower cost, smaller pixel size, larger array format size, higher operating temperature, and multi-band detection, which presents a number of serious challenges to current HgCdTe-based infrared technology. The primary challenges include well controlled p-type doping, lower cost, larger array format size, higher operating temperature, multi-band detection, and advanced plasma dry etching. Various new concepts and technologies are proposed and discussed that have the potential to overcome the existing primary challenges that are inhibiting the development of next generation HgCdTeinfrared detectortechnology.

Progress, challenges, and opportunities for HgCdTe infrared materials and detectors

Progress in focal plane array technologies

CCD and CMOS detectors each have strengths and weaknesses coming from their architecture or their fabrication process. This paper reviews their key architectural and technological differences that impact the photon detection performances and gives the future directions for CMOS detectors evolution.

/pdf/detection-of-visible-photons-in-ccd-and-cmos-a-comparative-4828ovsaza.pdf

Detection of visible photons in CCD and CMOS: A comparative view

Teledyne Imaging Sensors develops and produces high performance infrared sensors, electronics and packaging for
astronomy and civil space. These IR sensors are hybrid CMOS arrays, with HgCdTe used for light detection and a
silicon integrated circuit for signal readout. Teledyne manufactures IR sensors in a variety of sizes and formats.
Currently, the most advanced sensors are based on the Hawaii-2RG (H2RG), 2K×2K array with 18 μm pixel pitch. The
HgCdTe detector achieves very low dark current (<0.01 e-/pixel/sec) and high quantum efficiency (80-90%) over a wide
bandpass. Substrate-removed HgCdTe can simultaneously detect visible and infrared light, enabling spectrographs to
use a single focal plane array (FPA) for Visible-IR sensitivity. The SIDECARTM ASIC provides focal plane electronics
on a chip, operating in cryogenic environments with very low power (<11 mW). The H2RG and SIDECARTM have been
qualified to NASA Technology Readiness Level 6 (TRL-6). Teledyne continues to advance the state-of-the-art and is
producing a high speed, low noise array designed for IR wavefront sensing. Teledyne is also developing a 4K×4K, 15
µm pixel infrared array that will be a cost effective module for the large focal planes of the Extremely Large Telescopes
and future generation space astronomy missions.

Teledyne Imaging Sensors: infrared imaging technologies for astronomy and civil space

Disclosed is a High Dynamic Range Dual Mode (HDR-DM) input circuit unit cell (10) for use with an infrared (IR) radiation detector (D1). The readout circuit unit cell includes a plurality of transistors (M1, M2, M3 and M4), switches (S1, S2 and S3), and capacitances (Cfb, Cbl and CSH) that are controllably coupled together to form, in a first mode of operation below an illumination level threshold, a CTIA input circuit (12), and to form, in a second mode of operation above the illumination level threshold, a lower gain SFD input circuit (14).

High dynamic range dual mode charge transimpedance amplifier/source follower per detector input circuit

As 2nd and 3rd generation Focal Plane Arrays (FPA) become more complex, the readout integrated circuit (ROIC) has emerged as a major discriminator in system performance. The focus of development and advancement has traditionally involved the detector technology. Early ROICs were simple multiplexers that performed little if any signal processing on the detector diode signal. Advances in silicon fabrication processes for analog integrated circuits have opened a new era in IRFPAs where signal digital functions can be achieved on the focal plane. We present an overview of significant advances in the area of mixed mode ROIC designs that enable greater functionality and performance of the sensor chip assembly. Innovations, continuing progress in CMOS technology, and greater foundry access have allowed enhancements in practically every aspect of the ROIC, from sophisticated unit cells to lower noise and lower power signal paths to highly programmable digital support circuitry. Denser detector input circuits with active amplifiers (FEDI or CTIA) have been implemented in unit cells as small as 27 micrometer X 27 micrometer. In addition, multiple gain, temporal filtering, or spatial filtering capabilities have been incorporated into these small unit cells. Significant reductions in focal plane power have been fabricated and demonstrated enabling a factor of 2 increase in frame rates for very large staring FPAs and a factor of 4 increase in line rates for scanning FPAs. Other developments include, but are not limited to, alternative schemes for time-delayed integration (TDI) and breakthroughs for uncooled applications. As the chip designs increase in capability, greater systems on a chip are feasible, especially with more programmable features provided by the on-chip digital circuitry.

Overview of advances in high-performance ROIC designs for use with IRFPAs

In a first aspect of these teachings there is provided a radiation sensor that includes sensor optics having an entrance aperture and a two dimensional array of unit cells ( 10 ) spaced away from the aperture. Each unit cell includes a radiation detector (D 1 ) having an output coupled to an input of a gain element, and each gain element is constructed so as to have at least one component with a value selected to set the gain of the gain element to a value that is a function of the unit cell's location along an x-axis and along a y-axis within the two dimensional array. In this manner a compensation is made for a variation of scene illumination across the two dimensional array, where the variation in scene illumination results from a relative intensity of the energy impinging on a unit area of the two dimensional array that varies, for example, by the fourth power of cosine θ, where θ is an angle referenced to an optical axis of the radiation sensor. In a further aspect the radiation sensor includes a plurality of column readout circuits individual ones of which are switchably coupled to individual ones of the unit cells of one of the columns of unit cells. Each of the column readout circuits is constructed to have a first stage having a gain element with a-least one component that has a value selected to set the gain of the gain element to a value that is a function of the location of the column within the two dimensional array, and is further constructed to include a second stage having an input coupled to the first stage. The second stage includes a gain element having a gain that is varied as a function of a location within the two dimensional array of a row of unit cells that is being readout. In this case a combination of the gain of the first stage and the gain of the second stage compensates for a variation of scene illumination across the two dimensional array, where the variation in scene illumination results from the relative intensity of the energy impinging on the unit area of the two dimensional array that varies by the fourth power of cosine θ.

Two dimensional optical shading gain compensation for imaging sensors

A unit cell ( 20 ) is disclosed that has an input node for coupling to an output of a detector (D 1 ) of electromagnetic radiation, such as IR or visible radiation. The unit cell includes a first capacitor (C intA ) switchably coupled to the input node for receiving a charge signal from the detector, and for integrating the charge signal during a first integration period, as well as a second capacitor (C intB )switchably coupled to the input node for integrating the charge signal during a second integration period. The unit cell further includes an output multiplexer ( 32, 34 ) for selectively coupling the first capacitor and the second capacitor to an output signal line ( 38 ) during respective charge signal readout periods. In the preferred embodiment a duration of the first integration period is one of greater than or less than the second integration period, and the first integration period is one of non-overlapping or overlapping with the second integration period, and vice versa. The first integration period can be interleaved with the second integration period, or vice versa.

David J. Gulbransen

Papers

Teledyne Imaging Sensors: infrared imaging technologies for astronomy and civil space

High dynamic range dual mode charge transimpedance amplifier/source follower per detector input circuit

Overview of advances in high-performance ROIC designs for use with IRFPAs

Two dimensional optical shading gain compensation for imaging sensors

Multi-mode high capacity dual integration direct injection detector input circuit