1,720,967 research outputs found
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
320×240 oversampled digital single photon counting image sensor
No full textA 320×240 single photon avalanche diode (SPAD) based single photon counting image sensor is implemented in 0.13μm imaging CMOS with state of the art 8μm pixel pitch at 26.8% fill factor. The imager is demonstrated operating as a global shutter (GS) oversampled binary image sensor reading out at 5.14kFPS. Frames are accumulated in real time on FPGA to construct a 256 photon/8bit output image at 20FPS
A 9.8 μm sample and hold time to amplitude converter CMOS SPAD pixel
No full textA 9.8μm pitch SPAD-based pixel is presented with a novel and scalable Sample and Hold (S/H) Time to Amplitude Converter (TAC) pixel architecture offering the potential to create high spatial resolution Time Correlated Single Photon Counting (TCSPC) image sensors in the future. This pixel pitch is an order of magnitude smaller than previous TCSPC pixels. The NMOS-only TAC performance is measured in a single point TCSPC optical experimental setup. 93ps LSB time resolution is obtained over 80ns dynamic range. Dynamic range limitations are discussed and improvements are suggested
11.5 A time-correlated single-photon-counting sensor with 14GS/S histogramming time-to-digital converter
No full textTime-correlated single photon counting (TCSPC) is a photon-efficient technique to record ultra-fast optical waveforms found in numerous applications such as time-of-flight (ToF) range measurement (LIDAR) [1], ToF 3D imaging [2], scanning optical microscopy [3], diffuse optical tomography (DOT) and Raman sensing [4]. Typical instrumentation consists of a pulsed laser source, a discrete detector such as an avalanche photodiode (APD) or photomultiplier tube (PMT), time-to-digital converter (TDC) card and a FPGA or PC to assemble and compute histograms of photon time stamps. Cost and size restrict the number of channels of TCSPC hardware. Having few detection and conversion channels, the technique is limited to processing optical waveforms with low intensity, with less than one returned photon per laser pulse, to avoid pile-up distortion [4]. However, many ultra-fast optical waveforms exhibit high dynamic range in the number of photons emitted per laser pulse. Examples are signals observed at close range in ToF with multiple reflections, diffuse reflected photons in DOT or local variations in fluorescent dye concentration in microscopy. This paper provides a single integrated chip that reduces conventional TCSPC pile-up mechanisms by an order of magnitude through ultra-parallel realizations of both photon detection and time-resolving hardware. A TDC architecture is presented which combines the two step iterated TCSPC process of time-code generation, followed by memory lookup, increment and write, into one parallel direct-to-histogram conversion. The sensor achieves 71.4ps resolution, over 18.85ns dynamic range, with 14GS/s throughput. The sensor can process 1.7Gphoton/s and generate 21k histograms/s (with 4.6μs readout time), each capturing a total of 1.7kphotons in a 1μs exposure
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
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
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
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
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