Search

This paper presents an electron multiplication charge coupled device (EMCCD) based on capacitive deep trench isolation (CDTI) and developed using complementary metal oxide semiconductor (CMOS) technology. The CDTI transfer register offers a charge transfer inefficiency lower than 10 − 4 and a low dark current o 0.11 nA / cm 2 at room temperature. In this work, the timing diagram is adapted to use this CDTI transfer register in an electron multiplication mode. The results highlight some limitations of this device in such an EM configuration: for instance, an unexpected increase in the dark current is observed. A design modification is then proposed to overcome these limitations and rely on the addition of an electrode on the top of the register. Thus, this new device preserves the good transfer performance of the register while adding an electron multiplication function. Technology computer-aided design (TCAD) simulations in 2D and 3D are performed with this new design and reveal a very promising structure. [ABSTRACT FROM AUTHOR]

This paper presents an electron multiplication charge coupled device (EMCCD) based on capacitive deep trench isolation (CDTI) and developed using complementary metal oxide semiconductor (CMOS) technology. The CDTI transfer register offers a charge transfer inefficiency lower than 10−4 and a low dark current o 0.11nA/cm2 at room temperature. In this work, the timing diagram is adapted to use this CDTI transfer register in an electron multiplication mode. The results highlight some limitations of this device in such an EM configuration: for instance, an unexpected increase in the dark current is observed. A design modification is then proposed to overcome these limitations and rely on the addition of an electrode on the top of the register. Thus, this new device preserves the good transfer performance of the register while adding an electron multiplication function. Technology computer-aided design (TCAD) simulations in 2D and 3D are performed with this new design and reveal a very promising structure.

The use of luminescence signals from single mineral grains for optical dating has become a valuable and frequently utilised tool in Quaternary Geochronology. Single grain luminescence dating is particularly beneficial in complex depositional settings, however the ability to measure single grain signals also offers the opportunity to assess intrinsic luminescence properties of individual mineral grains. The use of spatially resolved luminescence technologies such as an electron multiplier charge coupled device is of benefit when making luminescence measurements at single grain scales because they allow stimulation with light emitting diodes, and this offers a number of key benefits related to stimulation power when it comes to the assessment of characteristics such as optically stimulated luminescence (OSL) decay rate and the calculation of parameters such as the fast ratio and photo ionisation cross-sections. In this paper, the intra- and inter-sample variability of sensitised single grain thermoluminescence (TL) and OSL signals is considered. A comparison between TL and OSL signals is undertaken, as well as calculation of the fast ratio, OSL component photo ionisation cross-sections, thermal stability, and characteristic dose for a suite of quartz samples from a range of geographic locations and depositional settings. For these heated signals, key findings include the lack of relationship between OSL signal intensity and dominance of the fast component, the fitting of two components (a fast and slow component) is the most common fit for single grain OSL signals, characteristic doses from fast dominated signals suggesting saturation at c. 150 Gy, and the identification of the ultrafast OSL component. Intra-sample variability across all measured parameters is observed, suggesting that for this suite of samples, variability is the norm rather than the exception, and that the intrinsic luminescence characteristics of quartz are variable and diverse. • EMCCD imaging used for measurement of single grain quartz luminescence signal properties • Photo ionisation cross-section values calculated from single grain quartz OSL signals • Although not common, the ultra-fast component is observed in some quartz OSL signals • Thermal stability measurements suggest general stability of the signals measured • Characteristic dose assessment suggests an upper D0 limit of ∼150 Gy for fast dominated signals [ABSTRACT FROM AUTHOR]

The mass ranges of meteors, imaged by electro-optical (EO) cameras and backscatter radar receivers, for the most part do not overlap. Typical EO systems detect meteoroid masses down to 10− 5 kg or roughly magnitude + 2 meteors when using moderate field of view optics, un-intensified optical components, and meteor entry velocities around 45 km/sec. This is near the high end of the mass range of typical meteor radar observations. Having the same mass meteor measured by different sensor wavelength bands would be a benefit in terms of calibrating mass estimations for both EO and radar. To that end, the University of Western Ontario (UWO) has acquired and deployed a very low light imaging system based on an electron-multiplying CCD camera technology. This embeds a very low noise, per pixel intensifier chip in a cooled camera setup with various options for frame rate, region of interest and binning. The EO system of optics and sensor was optimally configured to collect 32 frames per second in a square field of view 14.7 degrees on a side, achieving a single-frame stellar limiting magnitude of mG = + 10.5. The system typically observes meteors of + 6.5. Given this hardware configuration, we successfully met the challenges associated with the development of robust image processing algorithms, resulting in a new end-to-end processing pipeline now in operation since 2017. A key development in this pipeline has been the first true application of matched filter processing to process the faintest meteors possible in the EMCCD system while also yielding high quality automated metric measurements of meteor focal plane positions. With pairs of EMCCD systems deployed at two sites, triangulation and high accuracy orbits are one of the many products being generated by this system. These measurements will be coupled to observations from the Canadian Meteor Orbit Radar (CMOR) used for meteor plasma characterization and the Canadian Automated Meteor Observatory (CAMO) high resolution mirror tracking system. [ABSTRACT FROM AUTHOR]

The opercula of the gastropod Bithynia tentaculata is composed of calcite and exhibits three main thermoluminescence peaks at ∼100, 280 and 360 °C when heated at 0.5 °C.s−1. The two higher temperature peaks can be used for geological and archaeological dating, whilst the lower temperature peak has a lifetime of hours and is only seen after laboratory irradiation. This study explores whether this lower temperature TL peak can be used to assess the reproducibility of laboratory heating of opercula. As found in previous studies, the TL peak at ∼100 °C is seen to consist of at least two signals which have different lifetimes at room temperature. By fixing the interval between irradiation and measurement of the TL signal, the impact of these different lifetimes on the temperature at which the TL peak occurs (T m) can be reduced, and replicate measurements on a single operculum using the same radiation dose yield values of T m within 1 °C. Comparison of different opercula shows variation in T m of 9 °C when heating at 5 °C.s−1, interpreted as primarily arising from variation in thermal lag between the hotplate and the different samples assessed. Reducing the heating rate to 0.5 °C.s−1 reduces the variation in T m between opercula to 2 °C. Imaging the TL emission from opercula using an EMCCD shows spatial variation in heating, and also demonstrates the reduction in variability that can be achieved by using a slower heating rate. Thus, monitoring the position of the TL peak at ∼100 °C can be used to assess thermal reproducibility of TL measurements on calcitic opercula. • A TL peak at ∼100 °C in calcite is a composite of at least 2 first order peaks. • This TL peak can successfully monitor thermal reproducibility. • Thermal lag between the hotplate and opercula may cause variation in peak position. • A slow (0.5 °C.s−1) heating rate reduces the variability in peak position. • Peak position can be used as a rejection criterion to exclude data where thermal lag is too large. [ABSTRACT FROM AUTHOR]

This article describes the developed equipment that allows measuring the photoelectrical parameters of multielement photodetectors, specifically various formats of EMCCD (electron multiplying charge-coupled device) chips. The authors present the measuring techniques and test results on dark currents, output amplifier sensitivity, charge transfer efficiency, charge capacity and other parameters. The studies were conducted, both on the wafer and in the body, on samples of the following formats: 576×288, 640×512, 768×576, 1024×1024, and 1280×1024.

In the astronomical speckle interferometry, low-light CCD cameras such as the electron bombarded/multiplying CCDs (EB/EMCCDs) are being widely used for taking the faint speckle images. The detector noise affects the power spectral estimate of the astronomical object as well as the speckle noise does. The estimation errors of the object power spectrum are results of the propagation of the random fluctuations due to those noises. We have formulated a method for correcting and evaluating the estimation errors based on our detection model developed for EB/EMCCDs and the conventional model of the speckle noise. In our method, the error correction and evaluation are accomplished with the aid of the auxiliary data known as the dark and flat frames. The unbiased estimator of the object power spectrum and its SNR evaluator as derived above are verified using simulated data, where we have adopted the values of the detector parameters as obtained by measuring the actually used EMCCD camera in our observations. The results of the simulated experiments show that, within the diffraction cutoff frequency, our power spectral estimator is unbiased, and our SNR evaluator for that is useful except below the seeing cutoff. [ABSTRACT FROM AUTHOR]

Opercula of the gastropod Bithynia tentaculata are composed of calcite, and are typically 2–4 mm in length. They emit a thermoluminescence (TL) signal that can be used for dose reconstruction, and spatially resolved TL data from them can be obtained using an electron multiplying charge coupled device (EMCCD). However, when multiple measurements are made of the same sample with imaging detectors such as the EMCCD, registering the different images is crucial so that when regions of interest (ROI) are defined they consistently relate to the same part of the specimen. Previous work on opercula has undertaken this registration by hand, but this is prohibitively time consuming and is also potentially prone to human error. An automated registration process is described, and its use is illustrated using a dose recovery experiment. Without registration more than half of the regions of interest defined across the operculum failed the recycling test, and for those ROIs which did pass recycling the dose recovery ratio varied from 0.7 to 1.2. After registration more than 97% of ROIs passed recycling and all these ROIs gave dose recovery ratios within two sigma of unity. The automated registration process described here has potential for application to other types of solid sample such as rock slices provided they are not perfectly circular. • Imaging detectors providing new insights for dosimetry. • Registration of images essential for accurate spatially resolved analysis. • Automated image registration described for calcitic opercula. [ABSTRACT FROM AUTHOR]

This paper describes recent process modifications made to enhance the performance of interline and electron-multiplying charge-coupled-device (EMCCD) image sensors. By use of MeV ion implantation, quantum efficiency in the NIR region of the spectrum was increased by 2×, and image smear was reduced by 6 dB. By reducing the depth of the shallow photodiode (PD) implants, the photodiode-to-vertical-charge-coupled-device (VCCD) transfer gate voltage required for no-lag operation was reduced by 3 V, and the electronic shutter voltage was reduced by 9 V. The thinner, surface pinning layer also resulted in a reduction of smear by 4 dB in the blue portion of the visible spectrum. For EMCCDs, gain aging was eliminated by providing an oxide-only dielectric under its multiplication phase, while retaining the oxide-nitride-oxide (ONO) gate dielectrics elsewhere in the device. [ABSTRACT FROM AUTHOR]

Gravel-bed rivers transport large quantities of sediment from alpine sources to foreland sinks and are a key element in the sediment transport system of mountain regions. Generating a quantitative comprehension of the morphodynamics and sedimentary processes operating in gravel-bed rivers is a long-standing research goal in fluvial geomorphology. This constitutes the base for understanding fluvial sediment cascades, valley floor incision and mountain denudation as well as for managing flood and sediment hazard risks. The prediction of how riverbed texture, sediment load and channel morphology respond to changes in governing conditions (discharge, sediment supply, valley slope) remain complex and thus are still largely elusive. We systematically sampled the granitic fluvial lag deposits that are preserved in the river bed channel of the Solenzara in southern Corsica. We target the grain size range > 250 mm (gravels to boulders) and explore the capabilities of an EMCCD camera set-up for 2D rock surface dating. In this study the IRSL, post-IR-IRSL as well as the IRPL signals of these samples are investigated and compared with each other. In addition to generating 2D EMCCD images of rock luminescence, we also use a classic "drilling and slicing" approach to generate 1D luminescence-depth profiles by measuring individual rock slices under the photo multiplier tube. Advantages and disadvantages of the 1D versus 2D luminescence data for the Solenzara samples are discussed and initial rock surface burial ages for different grain sizes and sections of the fluvial lag deposit presented. The ultimate goal of this rock surface dating study is to better constrain the spatio-temporal pattern of bed load transport and formation of lag deposits on the scale of a fluvial channel. [ABSTRACT FROM AUTHOR]

Luminescence dating of rock surfaces is an emerging and exciting branch of research in geochronology with great application potential [1-3]. Originally, luminescence dating has been developed to constrain the burial age of fine-grained (i.e. sand to silt sized) Quaternary sediments, and today plays a key role in the geological and archaeological sciences. In contrast, luminescence dating of rock surfaces still undergoes substantial methodological development and testing [e.g. 4-7], yet, the technique holds great promises to constrain the age of hitherto undatable geological and archaeological materials or geomorphological landscape elements. As such, luminescence-based rock surface dating (RSD) is highly complementary to OSL sediment burial and other Quaternary dating techniques. RSD basically comes in two variants: rock surface burial dating (RSbD) and rock surface exposure dating (RSeD) and over the last decade has evolved into a highly active and promising geochronological research field. Meanwhile numerous ways of analyzing RSb and RSe luminescence data exist and different approaches to calculate rock surface ages have been introduced, yet no standardized way of handling RSb or RSe luminescence data has been put forward. Here we present an open-source software package that is based on the software language Python©. The program enables users to evaluate their rock surface luminescence data via a simple graphical user interface (GUI). The program allows processing of data which originate either from CCD or EMCCD images or from the conventional "drilling and slicing" approach and takes various types of OSL, IRSL and IRPL signals into account. We incorporated all currently available and stat-of-the art bleaching models into the software package and provide the user with maximum degree of flexibility for normalizing luminescence signals. In the case of RSeD a novel calibration procedure option is implemented, deemed to generate robust RSe ages [7]. Ultimately, the software allows single as well as multiple exposure and burial ages from rock surfaces to be derived. [ABSTRACT FROM AUTHOR]

Devices for imaging luminescence emissions have been used for a number of years [e.g. 1], but where analysis of a sequence of measurements of the luminescence signal following different treatments is required a significant challenge has been to accurately register the images so that a signal measured from a region of interest defined in one image is compared with the corresponding part of the other images. This is particularly an issue with automated instruments where sample repositioning varies from one measurement step to the next, resulting in samples moving laterally and/or rotationally with respect to the EMCCD field of view. The calcitic opercula of Bithynia tentaculata are of interest for their TL emission which grows to doses in excess of 8,000 Gy, meaning it is potentially able to date the entire Quaternary period. The opercula are teardrop shaped and typically 2-4 mm on their longest axis. Imaging using an EMCCD permits spatially resolved equivalent dose determination, but registering the images has been a major impediment to analysis of sequences of measurements. Previous work [2] manually determined the translation and rotation of the opercula using distinctive features on the periphery of the opercula as markers. However, this approach is time consuming, especially where between 30 and 50 images of each opercula may need to be aligned for a sequence of measurements; it is also prone to human error. An automated process of image registration has been developed using ImageJ [3] capable of tracking each opercula. This procedure identifies the outline of the opercula in each image and then registers them. Using the translation and rotation of each image, any region of interest defined on one image looks at the same part of the opercula on all other images. Additionally, since the process identifies the outline of the opercula it allows a series of morphometric measurements to be made automatically, and for a series of regions of interest to be defined within the confines of the outline shape. The new approach is described and illustrated. A number of techniques are used to assess the accuracy of the registration process, and the impact upon the determination of De or other measurements such as pulse annealing are shown. This approach could also have applications for other types of object, such as rock slices, although they would need to be non-circular to be able to assess rotation of the object. It could also be adapted to enable the comparison of images captured by different devices mounted on the same instrument. [ABSTRACT FROM AUTHOR]

Single grain quartz optically stimulated luminescence (OSL) dating has become a frequently used geochronological technique within earth and archaeological sciences. During routine single grain measurements within the Risø reader set-up, single grain luminescence signals are stimulated using a solidstate laser beam which is focused on individual grains mounted within specialized single grain discs, and signals are detected using a photomultiplier tube (PMT) [1]. The recently developed electron multiplier charge coupled device (EMCCD) Risø attachment [2] offers an alternative means of measuring luminescence signals from single grains, where signals are imaged rather than detected using a PMT, and signals are stimulated with light emitting diodes (LEDs) instead of a laser. Whilst the detection sensitivity of the EMCCD system is lower when compared with the laser system, using LEDs rather than a laser system for signal stimulation offers two key benefits. The first is that the LED power density is lower, resulting in a lower rate of charge de-trapping that can be of benefit for mathematical treatment such as curve deconvolution. The second is that the use of the LEDs for stimulation results in an effective stimulation power at the sample location within the reader which is more constant and consistent in comparison to the laser setup. This circumvents the unquantifiable variability in effective stimulation power associated with laser stimulation [3]. Therefore the EMCCD set-up can be used to better compare single grain luminescence signals, and offers the opportunity to capture single grain thermoluminescence signals, as well as OSL signals. Variability in the intrinsic properties of quartz OSL signals has been widely recognized, and for example intra- and inter-sample variation in signal intensity and characteristic dose are frequently commented upon in chronology-focused papers. Analyzing single grain quartz OSL signals imaged from a range of samples using a Risø EMCCD system, Durcan and Duller [4] report intra-sample signal intensities varying by 2-3 orders of magnitude, as well as variability in decay curve form and fast ratios. Photoionization cross sections from single grain signals were also presented, and differences in the number and combination of quartz components present was observed both within and between samples. This paper further develops this work by calculating characteristic doses and thermal stabilities from the same EMCCD-derived single grain signals. This extended single grain dataset of quartz luminescence signal properties will allow the relationship between commonly considered characteristics, such as sensitivity and degree of fast component domination in the signal, to be compared against signal properties such as saturation level and thermal stability. [ABSTRACT FROM AUTHOR]

Besides dating there is increasing attention to use luminescence dating as a method to trace sediment transport. Tracing methods require rapid repeated single-grain (SG) measurements on slow-to-bleach signals. In developing luminescence tracing techniques our focus is on single-grain feldspar luminescence, because the slow resetting speed of post-IR IRSL (pIRIR) and thermoluminescence (TL) signals make feldspar a potentially ideal intrinsic sediment tracer. Slow-to-bleach signals have a better transport memory imprinted. We seek the best approach in measuring these signal types. Conventional single-grain measurements are performed using laser-based stimulation combined with photon multiplier tube (PMT) detection. An alternative approach is to stimulate all grains on a singlegrain disc simultaneously by LED diodes and image the arising luminescence signal with an Electron Multiplying Charge-Coupled Device (EMCCD) camera [1]. The EMCCD camera is advantageous for tracing purposes because it may offer rapid measurement of large numbers of single grains. The EMCCD can spatially resolve all types of OSL signals, therefore also enabling single-grain TL measurements and polymineral approaches. Similar to conventional single grain methods, EMCCD detection allows rapid repeated measurements without user interference. Moreover, the EMCCD provides extreme low-level light detection for dimmer signals [1]. The EMCCD approach has the additional advantage of simultaneous measurement of all grains on the disc, minimizing thermal erosion during prolonged elevated-temperature post-IR measurements. So far comparison between the two systems has only been performed on quartz [2]. Here, we show our prospective feldspar results: the two systems yield similar dose estimations and the imaging system seems around twice less sensitive than the conventional system, which also has been concluded by Thomsen (2015) [2] on quartz data. We now aim to present our work on (1) optimization of feldspar system settings to maximize number of accepted grains for analysis, one of the aspects is optimization of the crosstalk trade-off (2) quantification of the differences between the two systems by performing dose recovery tests on the same samples (cross-referenced) on both machines for several pIRIR signals. Results are compared in terms of the obtained equivalent doses and percentage of grains accepted for analysis. Furthermore, we aim (3) to present the detection of SG feldspar thermoluminescence signals with the EMCCD, and place its use in the context of sediment tracing purposes. [ABSTRACT FROM AUTHOR]

Low-light camera is an indispensable component in various fluorescence microscopy techniques. However, choosing an appropriate low-light camera for a specific technique (for example, single molecule imaging) is always time-consuming and sometimes confusing, especially after the commercialization of a new type of camera called sCMOS camera, which is now receiving heavy demands and high praise from both academic and industrial users. In this tutorial, we try to provide a guide on how to fully access the performance of low-light cameras using a well-developed method called photon transfer curve (PTC). We first present a brief explanation on the key parameters for characterizing low-light cameras, then explain the experimental procedures on how to measure PTC. We also show the application of the PTC method in experimentally quantifying the performance of two representative low-light cameras. Finally, we extend the PTC method to provide offset map, read noise map, and gain map of individual pixels inside a camera.

The sensor response function of a color camera is very essential to understand an overall camera imaging pipeline and to process captured images. It is also true when we characterize underlying imaging behaviors of the electron multiplying charge coupled device (EMCCD) camera, which was recently proposed to acquire color images in low-light-level conditions. Unlike existing CCD cameras, the EMCCD camera contains partially uni-modal spectral sensitivity functions (SSFs), some of which consists of two base (bi-modal) functions, thus often leading to a serious color distortion in existing characterization techniques. To address this problem, we propose a novel method that corrects output colors of the EMCCD camera by analyzing its partially uni-modal characteristics. Specifically, our goal is to correct such color distortion by adjusting bi-modal SSFs to be uni-modal. We remove the secondary region of bi-modal channels using a pre-calculated spectral sensitivity of the EMCCD camera. Experimental results demonstrate that the proposed method reduces the color distortion as well as enlarges a color gamut, which is crucial to color reproduction. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. [ABSTRACT FROM AUTHOR]

Low-light camera is an indispensable component in various fluorescence microscopy techniques. However, choosing an appropriate low-light camera for a specific technique (for example, single molecule imaging) is always time-consuming and sometimes confusing, especially after the commercialization of a new type of camera called sCMOS camera, which is now receiving heavy demands and high praise from both academic and industrial users. In this tutorial, we try to provide a guide on how to fully access the performance of low-light cameras using a well-developed method called photon transfer curve (PTC). We first present a brief explanation on the key parameters for characterizing low-light cameras, then explain the experimental procedures on how to measure PTC. We also show the application of the PTC method in experimentally quantifying the performance of two representative low-light cameras. Finally, we extend the PTC method to provide offset map, read noise map, and gain map of individual pixels inside a camera. [ABSTRACT FROM AUTHOR]

Polarised light from astronomical targets can yield a wealth of information about their source radiation mechanisms, and about the geometry of the scattered light regions. Optical observations, of both the linear and circular polarisation components, have been impeded due to non-optimised instrumentation. The need for suitable observing conditions and the availability of luminous targets are also limiting factors. The science motivation of any instrument adds constraints to its operation such as high signal-to-noise (SNR) and detector readout speeds. These factors in particular lead to a wide range of sources that have yet to be observed. The Galway Astronomical Stokes Polarimeter (GASP) has been specifically designed to make observations of these sources. GASP uses division of amplitude polarimeter (DOAP) (Compain and Drevillon Appl. Opt. 37, 5938-5944, ) to measure the four components of the Stokes vector (I, Q, U and V) simultaneously, which eliminates the constraints placed upon the need for moving parts during observation, and offers a real-time complete measurement of polarisation. Results from the GASP calibration are presented in this work for both a 1D detector system, and a pixel-by-pixel analysis on a 2D detector system. Following Compain et al. (Appl. Opt. 38, 3490-3502 ) we use the Eigenvalue Calibration Method (ECM) to measure the polarimetric limitations of the instrument for each of the two systems. Consequently, the ECM is able to compensate for systematic errors introduced by the calibration optics, and it also accounts for all optical elements of the polarimeter in the output. Initial laboratory results of the ECM are presented, using APD detectors, where errors of 0.2 % and 0.1° were measured for the degree of linear polarisation (DOLP) and polarisation angle (PA) respectively. Channel-to-channel image registration is an important aspect of 2-D polarimetry. We present our calibration results of the measured Mueller matrix of each sample, used by the ECM, when 2 Andor iXon Ultra 897 detectors were loaned to the project. A set of Zenith flat-field images were recorded during an observing campaign at the Palomar 200 inch telescope in November 2012. From these we show the polarimetric errors from the spatial polarimetry indicating both the stability and absolute accuracy of GASP. [ABSTRACT FROM AUTHOR]

This paper describes recent process modifications made to enhance the performance of interline and electron-multiplying charge-coupled-device (EMCCD) image sensors. By use of MeV ion implantation, quantum efficiency in the NIR region of the spectrum was increased by 2×, and image smear was reduced by 6 dB. By reducing the depth of the shallow photodiode (PD) implants, the photodiode-to-vertical-charge-coupled-device (VCCD) transfer gate voltage required for no-lag operation was reduced by 3 V, and the electronic shutter voltage was reduced by 9 V. The thinner, surface pinning layer also resulted in a reduction of smear by 4 dB in the blue portion of the visible spectrum. For EMCCDs, gain aging was eliminated by providing an oxide-only dielectric under its multiplication phase, while retaining the oxide-nitride-oxide (ONO) gate dielectrics elsewhere in the device.

In optically stimulated luminescence (OSL) dating and other retrospective dosimetry studies there is considerable demand for the ability to measure luminescence from individual dosimeters in the size range 50–500 μm diameter, either as separate grains or as part of a matrix. This work tests the potential of an electron multiplying charge-coupled device (EMCCD), providing extremely low level light detection. We characterize the performance of the device by discussing reproducibility and evaluating uncertainties in OSL signals. Finally we derive a typical single grain natural dose distribution with associated uncertainties. [ABSTRACT FROM AUTHOR]

The CMOS sensor technologies evolve very fast and offer today very promising solutions to existing issues facing by imaging camera systems. CMOS sensors are very attractive for fast and sensitive imaging thanks to their low pixel noise (1e-) and their possibility of backside illumination. The ebCMOS group of IPNL has produced a camera system dedicated to Low Light Level detection and based on a 640 kPixels ebCMOS with its acquisition system. After reminding the principle of detection of an ebCMOS and the characteristics of our prototype, we confront our camera to other imaging systems. We compare the identification efficiency and the localization accuracy of a point source by four different photo-detection devices: the scientific CMOS (sCMOS), the Charge Coupled Device (CDD), the Electron Multiplying CCD (emCCD) and the Electron Bombarded CMOS (ebCMOS). Our ebCMOS camera is able to identify a single photon source in less than 10 ms with a localization accuracy better than 1 µm. We report as well efficiency measurement and the false positive identification of the ebCMOS camera by identifying more than hundreds of single photon sources in parallel. About 700 spots are identified with a detection efficiency higher than 90% and a false positive percentage lower than 5. With these measurements, we show that our target tracking algorithm can be implemented in real time at 500 frames per second under a photon flux of the order of 8000 photons per frame. These results demonstrate that the ebCMOS camera concept with its single photon detection and target tracking algorithm is one of the best devices for low light and fast applications such as bioluminescence imaging, quantum dots tracking or adaptive optics. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness.

The Super Advanced X-ray Emission Spectrometer (SAXES) at the Swiss Light Source contains a high resolution Charge-Coupled Device (CCD) camera used for Resonant Inelastic X-ray Scattering (RIXS). Using the current CCD-based camera system, the energy-dispersive spectrometer has an energy resolution (E/ΔE) of approximately 12,000 at 930eV. A recent study predicted that through an upgrade to the grating and camera system, the energy resolution could be improved by a factor of 2. In order to achieve this goal in the spectral domain, the spatial resolution of the CCD must be improved to better than 5µm from the current 24µm spatial resolution (FWHM). The 400eV–1600eV energy X-rays detected by this spectrometer primarily interact within the field free region of the CCD, producing electron clouds which will diffuse isotropically until they reach the depleted region and buried channel. This diffusion of the charge leads to events which are split across several pixels. Through the analysis of the charge distribution across the pixels, various centroiding techniques can be used to pinpoint the spatial location of the X-ray interaction to the sub-pixel level, greatly improving the spatial resolution achieved. Using the PolLux soft X-ray microspectroscopy endstation at the Swiss Light Source, a beam of X-rays of energies from 200eV to 1400eV can be focused down to a spot size of approximately 20nm. Scanning this spot across the 16µm square pixels allows the sub-pixel response to be investigated. Previous work has demonstrated the potential improvement in spatial resolution achievable by centroiding events in a standard CCD. An Electron-Multiplying CCD (EM-CCD) has been used to improve the signal to effective readout noise ratio achieved resulting in a worst-case spatial resolution measurement of 4.5±0.2μm and 3.9±0.1μm at 530eV and 680eV respectively. A method is described that allows the contribution of the X-ray spot size to be deconvolved from these worst-case resolution measurements, estimating the spatial resolution to be approximately 3.5µm and 3.0µm at 530eV and 680eV, well below the resolution limit of 5µm required to improve the spectral resolution by a factor of 2. [ABSTRACT FROM AUTHOR]

Two different kinds of metallic plates on a rotating disk target were irradiated with a MeV proton beam, and quasi-monochromatic pulsed X-rays with different energies around the absorption edge of the contrast medium were alternately produced. By using these dual-energy X-rays and a high-sensitivity X-ray movie camera, we took a motion picture of the transmission image of a periodically moving phantom, which simulated a rat heart as a test animal. We found that the enhanced movie imaging of the contrast agent is available by subtraction between adjacent picture frames. [ABSTRACT FROM AUTHOR]

A high resolution x-ray imaging system designated the solid state x-ray image intensifier (SSXII) is being developed as a potential replacement of conventional lower-resolution x-ray detectors for neurovascular interventions. The SSXII consists of a CsI(Tl) phosphor to convert x-rays to light, a fiber optic taper to extend the field-of-view and to couple the phosphor to an Electron-Multiplying CCD (EMCCD) which has a built-in gain to boost the signal above the read-out noise floor. A parallel cascade linear-system model is explored and applied to quantitatively analyze the signal and noise transfer at each stage, and optimize the detector performance. The modulation transfer function (MTF), detective quantum efficiency (DQE) and frequency dependent instrumentation noise equivalent exposure (INEE) can be obtained from the theoretical model and experimental measurement. Agreement of these results validates the effectiveness of the model. Finally, compared with the traditional flat-panel detector (FPD), the SSXII exhibits better performance with higher spatial resolution, higher DQE and lower INEE. [ABSTRACT FROM PUBLISHER]

Abstract: Spatially resolved OSL (SR-OSL) measurements are made with a scanning or imaging system that records luminescence emissions from known sources within a sample. This work is a first step toward the development of an SR-OSL methodology based on the imaging of ultraviolet OSL emissions with an EMCCD camera. We present UV OSL images of natural quartz extracts, OSL/TL/IR images of sandstone, image-based OSL measurements from aluminum oxide grains, and dose recovery experiments on aluminum oxide and Risø calibration quartz. Camera sensitivity and quantitative reproducibility indicate that EMCCD-based OSL dating is feasible. Further experimentation is necessary to adequately define the error sources and measurement limitations of EMCCDs in the OSL regime. [Copyright &y& Elsevier]

In recent years, there have been impressive advances in the technology of cameras using charged coupled devices (CCD's) and electron multiplying charged coupled devices (EMCCD's) that make possible a number of applications for the detection of ionizing radiation. The new cameras have quantum efficiencies exceeding 90%, effective noise levels less than one electron per pixel, and can be made to detect light ranging from the ultraviolet to the infrared. When combined with photomultiplier tubes (PMT's), and when used with Time-Projection-Chambers (TPC's) that contain narrow gap mesh charge amplification stages and scintillating gas compositions, these cameras can be used to provide three-dimensional images of particle tracks. There are many applications for such devices, including direction sensitive searches for dark matter, measurements of thermal and fast neutrons, and searches for double-beta-decay. I will describe the operation of optical TPC's and their various applications in this review article. [ABSTRACT FROM AUTHOR]

A lens-coupled electron multiplying charge-coupled device (EMCCD)-based gamma camera capable of performing photon counting for both 99mTc and 125I sources has been constructed. This system differs from previous EMCCD-based gamma cameras by using lens-coupling rather than fiber-optic coupling to transfer the light from the scintillating crystal to the EMCCD. The gamma camera described herein uses a micro-columnar CsI(Tl) crystal, two f/0.95 lenses, and a commercial camera containing the e2v CCD97 EMCCD that was cooled to --70°C. Acquisition of the video-rate frames from the CCD97 was performed using LabVIEW software. Real-time photon counting analysis of the individual scintillation flashes within the CCD97 frames was performed by using the LabVIEW IMAQ software module. An intrinsic resolution of 56 µm FWHM was measured by using a 25 µm slit collimator and 125I source. A single 0.5 mm diameter pinhole collimator was used for SPECT reconstruction of a mouse thyroid gland containing 100 µCi (3.7 MBq) of 125I uptake. We found that although the photopeak for 99mTc (140 keV) could be resolved, the photopeak for 125I (≈ 27 KeV) could not be fully resolved due to the low optical transfer efficiency of dual lens coupling (< 5%). Nonetheless, energy windowing for 125I sources was used to eliminate most of the background events, proving that high-resolution photon counting for low-energy sources can be achieved by using simple lens-coupling. [ABSTRACT FROM AUTHOR]

Our evaluation of a high-resolution digital imaging detector capable of providing millisecond time resolution and high sensitivity for neutrons is presented. This detector is a modified version of the high-resolution γ-ray imager developed previously at Radiation Monitoring Devices, Inc. (RMD, Inc.), and consists of an Electron Multiplying Charge Coupled Device (EMCCD) attached to a neutron-sensitive scintillator via a fiberoptic taper. By virtue of its internal gain, the EMCCD permits high speed readout without introducing additional noise, thereby enabling high frame rate operation with an enhanced signal-to-noise ratio (SNR). Detector sensitivity is enhanced through the use of a back-thinned EMCCD, which provides high quantum efficiency over a typical emission range for many neutron-sensitive scintillators. Preliminary evaluations conducted at the Liquids Reflectometer beam port of the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) demonstrate that this new detector has the sensitivity to detect individual neutrons and the acquisition speed to perform energy-selective imaging with a temporal resolution of milliseconds. While substantial improvements in timing and imaging performance are planned, this prototype detector has already generated the first ever images of the SNS Liquids Reflectometer beam profile and was also used to demonstrate a technique for obtaining Bragg edge transmission imaging using energy-selective neutrons. The preliminary data, along with the detector design, evaluation, and planned developments are discussed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: The technology behind the Electron-Multiplying Charge Coupled Device (EMCCD) was successfully exploited by e2v technologies in the late 1990s. Since then, many uses have been found for these low light level (L3) devices including surveillance and many scientific applications. The EMCCD increases or ‘multiplies’ the charge signal by the phenomenon of impact ionisation (or avalanche multiplication) allowing the detection of low signal events of only a few photons. When coupled with a scintillator, this low light capability can be used to image photon flashes from individual X-ray interaction events. The combination of depth of interaction effects in the scintillator, shot noise on the signal and the multiplication noise factor lead to large variations in the profile of the detected signal from a constant energy X-ray source. This variation leads to reduced spectral performance and can have adverse effects on the centering techniques used in photon-counting imagers. The concept of scale-space is similar in many ways to the Fourier or wavelet transforms. Automatic scale selection can be implemented through the scale-space transform as a method of fitting a known profile to the observed photon flash. The process is examined here in the context of the photon-counting EMCCD detector and the results obtained in both simulated and experimental data compared. Through the analysis of the fitting process and the results achieved, the implications on imaging performance and spectral resolution are discussed. [Copyright &y& Elsevier]

Optically stimulated luminescence (OSL) signals from individual quartz grains are frequently used for equivalent dose and age determination in luminescence dating. Typically, signals from individual grains are stimulated with a focussed solid-state laser and detected via a photomultiplier tube. In contrast to the light-emitting diodes (LEDs) usually used when stimulating multiple-grain aliquots, the laser has a much higher stimulation power density. An absolute value for the effective stimulation power cannot easily be quantified, and the power delivered to each grain cannot be considered consistent throughout a measurement sequence. Both intra- and inter-sample variability in single grain luminescence signals parameters such as dose response form, decay rate, and sensitivity have long been recognised, however there remains uncertainty over how much of this variability is intrinsic to quartz grains or whether some should be attributed to variation in the effective stimulation power associated with the laser system. To better characterise intrinsic variability of single quartz OSL signals, an electron multiplier charge coupled device (EMCCD) attachment for the Risø reader was used for detecting and imaging luminescence signals. Whilst the EMCCD system currently offers a lower detection sensitivity when compared to the laser system, the ability to use LEDs for stimulation of the OSL signal circumvents the power variability associated with the laser system and allows an investigation of intrinsic variability to be made. In this paper, signal intensity and the composition of components in single grain luminescence signals are considered, and curve deconvolution is undertaken to calculate photo ionisation cross-sections for single grain quartz signals. For the samples considered, intra-sample variability in these characteristics is observed in single grain quartz luminescence signals imaged using an EMCCD. • Single grain quartz luminescence signal properties investigated using EMCCD imaging. • Intra- and inter-sample variability in single grain quartz signals observed. • Correlation between signal intensity and dominance of the fast component not observed. • Photo ionisation cross-section values calculated from single grain quartz OSL signals. [ABSTRACT FROM AUTHOR]

Abstract: Two electron-multiplication, charge-coupled devices (e2v CCD97) were operated continuously for 52 days to assess their avalanche gain stability. This work was part of an evaluation study into their suitability for the radial velocity spectrometer (RVS) instrument on the European Space Agency''s Gaia cornerstone mission. After one day the device gain was stable to within 10%, and at the end of the test both devices reached the required multiplication gain of 8 with an avalanche electrode voltage of less than 36V. [Copyright &y& Elsevier]

Abstract: Typical confocal Raman images consist of thousands of individual spectra from which various pieces of information can be extracted in order to display certain chemical information as an image. In order to acquire these images in a reasonable amount of time, the time required for a single spectrum must be minimized. This can be achieved through the optimization of various parts of the confocal Raman microscope. This article describes the usage of an ultra-high throughput spectrometer in combination with a spectroscopic electron multiplying CCD (EMCCD) camera as a detector. The spectrometer is compared to a standard mirror-based Czerny–Turner spectrometer and shows twice the throughput over virtually the entire visible spectral range as well as an improvement in the line shape of recorded Raman bands. The ultra-high throughput spectrometer and the EMCCD camera in combination with a high throughput Raman microscope reduces the acquisition time for single spectra to a matter of milliseconds and significantly enhances the sensitivity of the instrument. Example measurements are presented to illustrate the speed and sensitivity of the system. [Copyright &y& Elsevier]

Autofluorescent algal samples were spiked with europium beads for analysis on a novel all-solid-state, time-gated luminescence (TGL) microscope. Pulsed UV excitation (365 nm) was provided by a high-power UV-LED source fitted to an Olympus BX51 microscope. An “Impactron” electron multiplying charge-coupled-device (CCD) camera acquired images in delayed luminescence mode. Second, we evaluated sensitivity of the instrument by acquiring images of immunofluorescently labeled Giardia cysts with a single-exposure period of 3 ms. The camera was triggered 3 μs after the LED had extinguished to yield a 14-fold increase in signal-to-noise ratio within a single 33 ms capture cycle. This novel instrument could be switched instantly from prompt epifluorescence mode to TGL mode for suppression of short-lived fluorescence. [ABSTRACT FROM AUTHOR]

The electron-multiplying charge-coupled device (EMCCD) offers improved quantum efficiencies (40 to 95%) over a broader range of wavelengths (400 to 900 nm) and a higher intrinsic resolution (<100 μm using photon counting) when compared to photomultiplier tubes. The electron gain achieved in the multiplication register of an EMCCD effectively reduces the readout noise to less than 1 electron/pixel, making them sensitive to single photoelectrons. Our prototype camera uses the Texas Instruments Impactron™ EMCCD model TC2S3SPD-B0 (7.4 μm square pixels) which is cooled under vacuum to -50°C using a four stage Peltier and liquid heat exchanger. Shuttered lens-coupling is used to image the optical light from a 3 mm thick monolithic CsI(TI) crystal. Precise clocking for the EMCCD is provided by a National Instruments FPGA controller (PCI-7811R) and Lab VIEW FPGA module (version 8.0). A custom built electronics box contains the clock driver circuitry and 16-bit video board for digital conversion of the video signal. Our optical coupling method differs from other EMCCD SPECT systems by using lenses rather than fiber optic bundles for transfer. TC253 characterization tests measured a maximum gain just over 1000 ×, dark current rate of 0.14 e/p/s, read noise of 18.2 e/p, and spurious charge generation of 4 e/p. A light integration intrinsic resolution of 110 μm FWHM was measured. Light integration images of a line phantom using a single pinhole collimator were used for SPECT reconstruction. We found the relative high spurious charge generation and low quantum efficiency of the TC253 made it incapable of photon counting for low energy sources using lens coupling. [ABSTRACT FROM AUTHOR]

Abstract: Third generation synchrotron sources such as the Advanced Photon Source at Argonne National Laboratory, Argonne, IL, are outstanding tools for X-ray diffraction (XRD) and scattering studies of non-crystalline biological materials. However, these studies are hindered by the lack of adequate detectors that can provide multiple frames of detailed structural information on the required millisecond time scale at the extremely high count rates available at the APS. RMD is developing a cost effective detector for time-resolved small angle X-ray scattering (SAXS), using a cooled, 512×512 pixel electron multiplying CCD (EMCCD). This paper describes the detector design, its efficacy for time-resolved SAXS studies, and its imaging performance with frame rates of 30–500fps. [Copyright &y& Elsevier]

Dedicated MicroCT systems for noninvasive screening of small animals are now in routine use. However, speed of operation limits their use for functional studies. At Radiation Monitoring Devices (RMD), we are addressing this need by developing a digital X-ray detector that can simultaneously provide high speed, high sensitivity, and a large active imaging area. The system consists of a special high-speed CCD detector optically coupled to a scintillator. In its current configuration, the system provides an active area of 5 cm × 5 cm, a spatial resolution of ∼100 μm, and can operate at speeds of up to 225 frames per second. The system has been used to acquire volumetric CT data with 360 projections in ∼12 seconds compared to several minutes needed for most commercial systems. This paper presents the design of various system components and performance characterization with CT reconstruction data from a mouse phantom. [ABSTRACT FROM AUTHOR]

This paper presents the design and feasibility study of a very-high resolution gamma camera for detecting 27–35 keV X and gamma rays emitted by I-125 labelled radiotracers. This detector consists of a newly developed Electron-multiplying CCD (EMCCD) sensor and a de-magnifier tube coupled to a thin layer of scintillator. A prototype detector was developed and experimentally evaluated. This detector has a detection area of ∼5 × 5 cm². It provided an intrinsic spatial resolution of <60 μm FWHM and a high signal-to-noise ratio for detecting the 27–35 keV photons, which ensures an excellent counting efficiency. This detector will be used as the key component for a single photon emission microscope (SPEM) system that is under development. [ABSTRACT FROM AUTHOR]

Abstract: Raman microspectroscopy is widely used for musculoskeletal tissues studies. But the fluorescence background obscures prominent Raman bands of mineral and matrix components of bone tissue. A 532-nm laser irradiation has been used efficiently to remove the fluorescence background from Raman spectra of cortical bone. Photochemical bleaching reduces over 80% of the fluorescence background after 2 h and is found to be nondestructive within 40 min. The use of electron multiplying couple charge detector (EMCCD) enables to acquire Raman spectra of bone tissues within 1–5 s range and to obtain Raman images less than in 10 min. [Copyright &y& Elsevier]

Abstract: New designs of electron multiplying charge coupled devices (EMCCDs) combine superior spatial resolution and low noise of a conventional CCD with the internal gain of an avalanche photodiode (APD). The presence of internal gain not only enhances the device sensitivity, but virtually eliminates the read noise associated with current CCDs, even when the device is read at very high frame rates of 100 frames per second or higher. Thus, the EMCCDs can simultaneously provide very high sensitivity and a high signal-to-noise ratio (SNR). At RMD we are exploiting these properties of EMCCD for use in radionuclide and X-ray imaging. Specifically, we have developed a system that makes use of an EMCCD with 512 × 512, 16 × 16μm pixels. Special fiberoptic reducers have been designed to enhance the detector sensitive area. The system gain is software selectable and may be varied from 1 to 1000. This paper describes the detector design along with its γ-ray/X-ray imaging performance. [Copyright &y& Elsevier]

Super-resolution Radial Fluctuations (SRRF) imaging is a computational approach to fixed and live-cell super-resolution microscopy that is highly accessible to life science researchers since it uses common microscopes and open-source software plugins for ImageJ. This allows users to generate super-resolution images using the same equipment, fluorophores, fluorescent proteins and methods they routinely employ for their studies without specialized sample preparations or reagents. Here, we discuss a step-by-step workflow for acquiring and analyzing images using the NanoJ-SRRF software developed by the Ricardo Henriques group, with a focus on imaging chromatin. Increased accessibility of affordable super-resolution imaging techniques is an important step in extending the reach of this revolution in cellular imaging to a greater number of laboratories., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Electron Multiplying Charge Coupled Devices, EMCCD are used as x-ray detectors. The NSLS-II Soft Inelastic x-ray Scattering (SIX) beam line has two EMCCDs for x-ray detection in the spectrometer arm. The spectrometer with high resolving power disperses x-rays vertically. The x-ray vertical position on the sensor plane is related to its energy. This allows for very accurate x-ray energy measurements through x-ray coordinates. X-rays interact with silicon and create a number of electron–hole pairs proportional to the x-ray energy. Electrons drift and diffuse toward pixel gates and are collected there. The diffused electrons form a charge cloud distributed over several neighboring pixels. This charge sharing enables coordinate measurements with accuracy better than the pixel pitch. The charge distribution shape has to be taken into account to achieve ultimate accuracy in coordinate measurements. In this paper, we present a method of the charge distribution shape analysis and demonstrate its applications. The drift and diffusion of electrons from the point of generation to pixel gates results in the bell-shaped electron cloud usually approximated by Gaussian shape. The number of electrons collected under a pixel is proportional to the shape function integral. These electron packets get transferred to the sense node of the output amplifier. The transfer process could introduce distortions to the original charge distribution. For example, during transfers, electrons in the packet could be exposed to traps if they are present in the sensor. The trapping and later the release processes distort the apparent shape of the charge distribution. Therefore, deviations of the charge distribution shape from the originally symmetrical form can indicate the presence of trap centers in the sensor and can be used for sensor diagnostics. [ABSTRACT FROM AUTHOR]