1,720,993 research outputs found
Avalanche-mode High Frame Rate, Low Light CMOS Single Photon Image Sensors
No full textOur recent progress in CMOS single-photon avalanche diode (SPAD) image sensors will be presented. We will highlight areas where these can compete with existing low-light imaging technologies using examples from superresolution microscopy. Article not available
Single Photon Counting Performance and Noise Analysis of CMOS SPAD-based Image Sensors
Full text linkSPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A Simulation Model for Digital Silicon Photomultipliers
Full text linkWe propose a simulator model to estimate theperformance of digital Silicon Photomultipliers (dSiPM)based on Single Photon Avalanche Diodes (SPADs) in termsof detection rate of photons incident on the sensor. The workprovides guidelines for efficient array structure dependingon: the number of SPADs, fill factor, area of both SPADsand array. A comparison of the main techniques present inthe literature to digitally combine multiple outputs into singlechannel is included
Digital Silicon Photomultipliers with OR/XOR Pulse Combining Techniques
Full text linkrecently proposed XOR-based Digital SiliconPhotomultiplier is compared against the OR-based counterpart.We show experimental data from a set of SPAD pixelarrays in 130nm CMOS process with selectable OR tree andXOR tree for direct comparison. We demonstrate how XOR baseddSiPMs solve the limitation caused by monostablecircuits and reach higher maximum count rates comparedto optimised OR-based dSiPMs. The increased throughputof the SPAD array allows higher sampling rates for thedigitisation of the light signal enhancing dynamic range andlinearity
A SPAD-Based QVGA Image Sensor for Single-Photon Counting and Quanta Imaging
Full text linkA CMOS single-photon avalanche diode (SPAD)-based quarter video graphics array image sensor with 8-μm pixel pitch and 26.8% fill factor (FF) is presented. The combination of analog pixel electronics and scalable shared-well SPAD devices facilitates high-resolution, high-FF SPAD imaging arrays exhibiting photon shot-noise-limited statistics. The SPAD has 47 counts/s dark count rate at 1.5 V excess bias (EB), 39.5% photon detection probability (PDP) at 480 nm, and a minimum of 1.1 ns dead time at 1 V EB. Analog single-photon counting imaging is demonstrated with maximum 14.2-mV/SPAD event sensitivity and 0.06e - minimum equivalent read noise. Binary quanta image sensor (QIS) 16-kframes/s real-time oversampling is shown, verifying single-photon QIS theory with 4.6× overexposure latitude and 0.168e - read noise
Analysis of Photon Detection Efficiency and Dynamic Range in SPAD based Visible Light Receivers
Full text linkWe investigate the photon detection efficiency and the dynamic range for digital silicon photomultipliers(dSiPMs) over a selection of design parameters: SPAD dead time, photon detection efficiency, SPAD device area and fill factor, number of SPADs and total dSiPM active area. Two receiver scaling scenarios are considered: varying the number of SPADs for (1) a fixed SPAD area or (2) a fixed SPAD arrayarea. Theoretical and simulated results are confirmed with experimental data from a selection of dSiPMs realised on a test chip in 130nm CMOS process
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