Showing papers by "Robert Henderson published in 2016"

The Pan-STARRS1 Surveys

Abstract: Pan-STARRS1 has carried out a set of distinct synoptic imaging sky surveys including the $3\pi$ Steradian Survey and the Medium Deep Survey in 5 bands ($grizy_{P1}$). The mean 5$\sigma$ point source limiting sensitivities in the stacked 3$\pi$ Steradian Survey in $grizy_{P1}$ are (23.3, 23.2, 23.1, 22.3, 21.4) respectively. The upper bound on the systematic uncertainty in the photometric calibration across the sky is 7-12 millimag depending on the bandpass. The systematic uncertainty of the astrometric calibration using the Gaia frame comes from a comparison of the results with Gaia: the standard deviation of the mean and median residuals ($ \Delta ra, \Delta dec $) are (2.3, 1.7) milliarcsec, and (3.1, 4.8) milliarcsec respectively. The Pan-STARRS system and the design of the PS1 surveys are described and an overview of the resulting image and catalog data products and their basic characteristics are described together with a summary of important results. The images, reduced data products, and derived data products from the Pan-STARRS1 surveys are available to the community from the Mikulski Archive for Space Telescopes (MAST) at STScI.

The Pan-STARRS1 Database and Data Products

Abstract: This paper describes the organization of the database and the catalog data products from the Pan-STARRS1 $3\pi$ Steradian Survey. The catalog data products are available in the form of an SQL-based relational database from MAST, the Mikulski Archive for Space Telescopes at STScI. The database is described in detail, including the construction of the database, the provenance of the data, the schema, and how the database tables are related. Examples of queries for a range of science goals are included. The catalog data products are available in the form of an SQL-based relational database from MAST, the Mikulski Archive for Space Telescopes at STScI.

Detection and tracking of moving objects hidden from view

Abstract: Scientists demonstrate an experimental method that allows them to locate and track moving targets that are hidden from the direct line of sight, for example, by a wall or an obstacle, with only a few seconds acquisition time and centimetre precision. The ability to detect motion and track a moving object hidden around a corner or behind a wall provides a crucial advantage when physically going around the obstacle is impossible or dangerous. Previous methods have demonstrated that it is possible to reconstruct the shape of an object hidden from view. However, these methods do not enable the tracking of movement in real time. We demonstrate a compact non-line-of-sight laser ranging technology that relies on the ability to send light around an obstacle using a scattering floor and then detect the return signal from a hidden object within only a few seconds of acquisition time. By detecting this signal with a single-photon avalanche diode (SPAD) camera, we follow the movement of an object located a metre away from the camera with centimetre precision. We discuss the possibility of applying this technology to a variety of real-life situations in the near future.

A SPAD-Based QVGA Image Sensor for Single-Photon Counting and Quanta Imaging

Abstract: A CMOS single-photon avalanche diode (SPAD)-based quarter video graphics array image sensor with 8- $\mu \text{m}$ 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\times $ overexposure latitude and 0.168e− read noise.

Backside illuminated SPAD image sensor with 7.83μm pitch in 3D-stacked CMOS technology

Abstract: We present the first 3D-stacked backside illuminated (BSI) single photon avalanche diode (SPAD) image sensor capable of both single photon counting (SPC) intensity, and time resolved imaging. The 128×120 prototype has a pixel pitch of 7.83 μm making it the smallest pixel reported for SPAD image sensors. A low power, high density 40nm bottom tier hosts the quenching front end and processing electronics while an imaging specific 65nm top tier hosts the photo-detectors with a 1-to-1 hybrid bond connection [1]. The SPAD exhibits a median dark count rate (DCR) below 200cps at room temperature and 1V excess bias, and has a peak photon detection probability (PDP) of 27.5% at 640nm and 3 V excess bias.

Real-time fluorescence lifetime actuation for cell sorting using a CMOS SPAD silicon photomultiplier

Abstract: Time-correlated single photon counting (TCSPC) is a fundamental fluorescence lifetime measurement technique offering high signal to noise ratio (SNR). However, its requirement for complex software algorithms for histogram processing restricts throughput in flow cytometers and prevents on-the-fly sorting of cells. We present a single-point digital silicon photomultiplier (SiPM) detector accomplishing real-time fluorescence lifetime-activated actuation targeting cell sorting applications in flow cytometry. The sensor also achieves burst-integrated fluorescence lifetime (BIFL) detection by TCSPC. The SiPM is a single-chip complementary metal-oxide-semiconductor (CMOS) sensor employing a 32×32 single-photon avalanche diode (SPAD) array and eight pairs of time-interleaved time to digital converters (TI-TDCs) with a 50 ps minimum timing resolution. The sensor's pile-up resistant embedded center of mass method (CMM) processor accomplishes low-latency measurement and thresholding of fluorescence lifetime. A digital control signal is generated with a 16.6 μs latency for cell sorter actuation allowing a maximum cell throughput of 60,000 cells per second and an error rate of 0.6%.

New high-speed centre of mass method incorporating background subtraction for accurate determination of fluorescence lifetime

Abstract: We demonstrate an implementation of a centre-of-mass method (CMM) incorporating background subtraction for use in multifocal fluorescence lifetime imaging microscopy to accurately determine fluorescence lifetime in live cell imaging using the Megaframe camera. The inclusion of background subtraction solves one of the major issues associated with centre-of-mass approaches, namely the sensitivity of the algorithm to background signal. The algorithm, which is predominantly implemented in hardware, provides real-time lifetime output and allows the user to effectively condense large amounts of photon data. Instead of requiring the transfer of thousands of photon arrival times, the lifetime is simply represented by one value which allows the system to collect data up to limit of pulse pile-up without any limitations on data transfer rates. In order to evaluate the performance of this new CMM algorithm with existing techniques (i.e. rapid lifetime determination and Levenburg-Marquardt), we imaged live MCF-7 human breast carcinoma cells transiently transfected with FRET standards. We show that, it offers significant advantages in terms of lifetime accuracy and insensitivity to variability in dark count rate (DCR) between Megaframe camera pixels. Unlike other algorithms no prior knowledge of the expected lifetime is required to perform lifetime determination. The ability of this technique to provide real-time lifetime readout makes it extremely useful for a number of applications.

Single Photon Counting Performance and Noise Analysis of CMOS SPAD-based Image Sensors

Abstract: SPAD-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.

Detection and tracking of moving objects hidden from view

Abstract: We use a femtosecond laser and a single-photon avalanche diode (SPAD) camera to develop a system that is able to locate objects hidden from view and track their motion.

Observation of image pair creation and annihilation from superluminal scattering sources

Abstract: The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena.

Digital Silicon Photomultipliers With OR/XOR Pulse Combining Techniques

Abstract: A recently proposed XOR-based digital silicon photomultiplier (dSiPM) is compared against the OR-based counterpart. We show experimental data from a set of single-photon avalanche diode (SPAD) pixel arrays in 130-nm CMOS process with selectable OR tree and XOR tree for direct comparison. We demonstrate how XOR-based dSiPMs solve the limitation caused by monostable circuits and reach higher maximum count rates compared with optimized OR-based dSiPMs. The increased throughput of the SPAD array allows higher sampling rates for the digitization of the light signal enhancing dynamic range and linearity.

Smart-aggregation imaging for single molecule localization with SPAD cameras

Abstract: SPAD cameras offer single photon detection sensitivity, high frame rates and zero readout noise. They are a core technology for widefield FLIM, but have further potential in ultra-fast imaging applications. However, in practice sensitivity falls behind that of EMCCD and sCMOS devices due to the lower photon detection efficiency of SPAD arrays. This paper considers the application of a binary SPAD camera to the capture of blinking molecules as part of a superresolution (dSTORM/PALM) experiment. Simulation and experimental studies demonstrate that the effective sensitivity of the camera can be improved significantly by aggregation of signal only binary frames. The simulations also indicate that with future advances in SPAD camera technology, SPAD devices could in time outperform existing scientific cameras when capturing fast temporal dynamics.

60 Mb/s, 2 meters visible light communications in 1 klx ambient using an unlensed CMOS SPAD receiver

Abstract: We demonstrate an optical link operating in indoor ambient lighting conditions using a CMOS single photon avalanche diode (SPAD) optical receiver and a RGB light emitting diode (LED). The high sensitivity of the SPAD receiver allows the link to operate at 2 m distance at a total 60 Mb/s and bit error rate (BER) of 1×10−3 without lensing. The transmitter implements color shift keying (CSK) using a custom 4-channel current mode CMOS digital to analog converter (DAC). The miniaturized, low cost components employed at transmitter and receiver are suited to integration in portable electronic devices or chip-in-a-bulb respectively.

Analysis of Photon Detection Efficiency and Dynamic Range in SPAD-Based Visible Light Receivers

Abstract: We investigate the photon detection efficiency (PDE) and the dynamic range for digital silicon photomultipliers (dSiPMs) over a selection of design parameters: dSiPM unit cell dead time, PDE, unit cell area and fill factor, number of cells, and total dSiPM active area. Two receiver scaling scenarios are considered: varying the number of cells for 1) a fixed unit cell area or 2) a fixed total dSiPM area. Theoretical and simulated results are confirmed with experimental data from a selection of dSiPMs realised on a test chip in $\mathbf {130{\rm{-}nm}}$ CMOS process.

Smart-aggregation imaging for single molecule localisation with SPAD cameras.

Abstract: Single molecule localisation microscopy (SMLM) has become an essential part of the super-resolution toolbox for probing cellular structure and function. The rapid evolution of these techniques has outstripped detector development and faster, more sensitive cameras are required to further improve localisation certainty. Single-photon avalanche photodiode (SPAD) array cameras offer single-photon sensitivity, very high frame rates and zero readout noise, making them a potentially ideal detector for ultra-fast imaging and SMLM experiments. However, performance traditionally falls behind that of emCCD and sCMOS devices due to lower photon detection efficiency. Here we demonstrate, both experimentally and through simulations, that the sensitivity of a binary SPAD camera in SMLM experiments can be improved significantly by aggregating only frames containing signal, and that this leads to smaller datasets and competitive performance with that of existing detectors. The simulations also indicate that with predicted future advances in SPAD camera technology, SPAD devices will outperform existing scientific cameras when capturing fast temporal dynamics.

Back-illuminated voltage-domain global shutter CMOS image sensor with 3.75µm pixels and dual in-pixel storage nodes

Abstract: A 1024×800 image sensor with voltage-domain global shutter pixels and dual in-pixel storage is implemented in a 90nm/65nm back-illuminated (BSI) imaging process. The pixel has a 3.75µm pitch, achieves −80dB PLS operating in its correlated double sampling mode and has a maximum dynamic range in its high-dynamic range imaging mode of 102dB.

256×256, 100kfps, 61% Fill-factor time-resolved SPAD image sensor for microscopy applications

Abstract: A 256×256 Single Photon Avalanche Diode (SPAD) image sensor operating at 100kfps with fill factor of 61% and pixel pitch of 16μm is reported. An all-NMOS 7T pixel allows high uniformity gated operation down to 4ns and ∼600ps fall time with on-chip delay generation. The sensor operates with 0.996 temporal aperture ratio (TAR) in rolling shutter and has a parasitic light sensitivity (PLS) in excess of −160dB when operated in global shutter. Gating and cooling allow the suppression of dark noise, which, in combination with the high fill factor, enables competitive low-light performance with electron multiplying CCDs (EMCCDs) whilst offering time-resolved imaging modes.

A Simulation Model for Digital Silicon Photomultipliers

Abstract: We propose a simulator model to estimate the performance of digital Silicon Photomultipliers (dSiPM) based on Single Photon Avalanche Diodes (SPADs) in terms of detection rate of photons incident on the sensor. The work provides guidelines for efficient array structure depending on: the number of SPADs, fill factor, area of both SPADs and array. A comparison of the main techniques present in the literature to digitally combine multiple outputs into single channel is included with simulated results showing promising higher detection rates for XOR-based dSiPMs. Mathematical expressions are derived to estimate dSiPM parameters such as maximum detection rate and detector dead time as functions of the mentioned design parameters.

GaN based μLED drive circuit for Visible Light Communication (VLC) with improved linearity using on-chip optical feedback

Abstract: Solid-state lighting is a rapidly developing field. Visible Light Emitting Diodes (LEDs) are becoming more efficient, have high reliability and can be incorporated into many lighting applications. LED is predicted to become the main source of general illumination due to its high energy efficiency. Such source can also modulate at high speed, thus offering a prospect of illumination and communications simultaneously. Various modulation techniques have been employed such as OOK and OFDM, where the latter has shown ability to transmit into Gb/s region. However, OFDM requires high linearity response from the driver's optical power output. In this paper, we present a drive circuit for GaN μLED which employs on-chip optical feedback technique to suppress non-linearity of the optical power output from the μLED for Visible Light Communication (VLC) with OFDM modulation.

Observation of Laser Pulse Propagation in Optical Fibers with a SPAD Camera

Abstract: We use a single-photon avalanche detector array camera with pico-second timing accuracy to rapidly characterise and film the propagation of various laser pulses in optical fiber. We present results of supercontinuum generation and the tracking of a GHz pulse train.

100 Mb/s wavelength division multiplexing visible light communications link using a triple-junction photo-diode

Abstract: We report the experimental realization of a 100 Mb/s wavelength division multiplexing link using commercial visible LED sources and a triple-junction photo-diode receiver. This is the first demonstration where multiple-junction technology is used for Visible Light Communication, showing its potential as a compact wavelength-selective transceiver.

Time-resolved non-sequential ray-tracing modelling of non-line-of-sight picosecond pulse LIDAR

Abstract: The ability to detect motion and to track a moving object that is hidden around a corner or behind a wall provides a crucial advantage when physically going around the obstacle is impossible or dangerous. One recently demonstrated approach to achieving this goal makes use of non-line-of-sight picosecond pulse laser ranging. This approach has recently become interesting due to the availability of single-photon avalanche diode (SPAD) receivers with picosecond time resolution. We present a time-resolved non-sequential ray-tracing model and its application to indirect line-of-sight detection of moving targets. The model makes use of the Zemax optical design programme's capabilities in stray light analysis where it traces large numbers of rays through multiple random scattering events in a 3D non-sequential environment. Our model then reconstructs the generated multi-segment ray paths and adds temporal analysis. Validation of this model against experimental results is shown. We then exercise the model to explore the limits placed on system design by available laser sources and detectors. In particular we detail the requirements on the laser's pulse energy, duration and repetition rate, and on the receiver's temporal response and sensitivity. These are discussed in terms of the resulting implications for achievable range, resolution and measurement time while retaining eye-safety with this technique. Finally, the model is used to examine potential extensions to the experimental system that may allow for increased localisation of the position of the detected moving object, such as the inclusion of multiple detectors and/or multiple emitters.

Imaging quantum correlations with a single-photon detector array

Abstract: We image quantum correlations arising from parametric downconversion with a single-photon sensitive detector array. This opens up a number of possibilities in quantum science, including demonstrations of the EPR paradox without background subtraction.

TACImager: a high frame rate 320 x 256 SPAD time to amplitude converter array with adjustable time zoom

Abstract: Single-photon avalanche diodes (SPADs) in the form of high-resolution imaging pixel arrays are used in 3D cameras, motion-tracking, biomedical and time-correlated single photon counting (TCSPC) applications. Rapid spatial and temporal zoom onto objects of interest is an attractive feature. We present here novel high-speed time-zoom functionality achieved with the digital readout mode of the TACImager, a 256 x 256 TCSPC image sensor array based on sample and hold Time to Amplitude Converter (TAC) pixels. A column-parallel flash Analogue to Digital Converter (ADC) is implemented in the TACImager to support fast digital readout, allowing per-pixel, 3-bin TCSPC histogramming at frame rates of 4 kfps. New results related to this high-speed mode of operation are presented. The TACImager utilises a global ramp voltage as a timing reference, allowing time-zoom to be achieved through dynamic adjustment of comparator voltages, ramp offset voltages and ramp waveforms. We demonstrate the influence of fixed pattern noise in the pixels and column parallel ADCs on the results.

Picosecond time-resolved imaging using SPAD cameras

Abstract: The recent development of 2D arrays of single-photon avalanche diodes (SPAD) has driven the development of applications based on the ability to capture light in motion. Such arrays are composed typically of 32x32 SPAD detectors, each having the ability to detect single photons and measure their time of arrival with a resolution of about 100 ps. Thanks to the single-photon sensitivity and the high temporal resolution of these detectors, it is now possible to image light as it is travelling on a centimetre scale. This opens the door for the direct observation and study of dynamics evolving over picoseconds and nanoseconds timescales such as laser propagation in air, laser-induced plasma and laser propagation in optical fibres. Another interesting application enabled by the ability to image light in motion is the detection of objects hidden from view, based on the recording of scattered waves originating from objects hidden by an obstacle. Similarly to LIDAR systems, the temporal information acquired at every pixel of a SPAD array, combined with the spatial information it provides, allows to pinpoint the position of an object located outside the line-of-sight of the detector. A non-line-of-sight tracking can be a valuable asset in many scenarios, including for search and rescue mission and safer autonomous driving.

The Pan-STARRS1 Surveys

Abstract: Author(s): Chambers, KC; Magnier, EA; Metcalfe, N; Flewelling, HA; Huber, ME; Waters, CZ; Denneau, L; Draper, PW; Farrow, D; Finkbeiner, DP; Holmberg, C; Koppenhoefer, J; Price, PA; Rest, A; Saglia, RP; Schlafly, EF; Smartt, SJ; Sweeney, W; Wainscoat, RJ; Burgett, WS; Chastel, S; Grav, T; Heasley, JN; Hodapp, KW; Jedicke, R; Kaiser, N; Kudritzki, R-P; Luppino, GA; Lupton, RH; Monet, DG; Morgan, JS; Onaka, PM; Shiao, B; Stubbs, CW; Tonry, JL; White, R; Banados, E; Bell, EF; Bender, R; Bernard, EJ; Boegner, M; Boffi, F; Botticella, MT; Calamida, A; Casertano, S; Chen, W-P; Chen, X; Cole, S; Deacon, N; Frenk, C; Fitzsimmons, A; Gezari, S; Gibbs, V; Goessl, C; Goggia, T; Gourgue, R; Goldman, B; Grant, P; Grebel, EK; Hambly, NC; Hasinger, G; Heavens, AF; Heckman, TM; Henderson, R; Henning, T; Holman, M; Hopp, U; Ip, W-H; Isani, S; Jackson, M; Keyes, CD; Koekemoer, AM; Kotak, R; Le, D; Liska, D; Long, KS; Lucey, JR; Liu, M; Martin, NF; Masci, G; McLean, B; Mindel, E; Misra, P; Morganson, E; Murphy, DNA | Abstract: Pan-STARRS1 has carried out a set of distinct synoptic imaging sky surveys including the $3\pi$ Steradian Survey and the Medium Deep Survey in 5 bands ($grizy_{P1}$). The mean 5$\sigma$ point source limiting sensitivities in the stacked 3$\pi$ Steradian Survey in $grizy_{P1}$ are (23.3, 23.2, 23.1, 22.3, 21.4) respectively. The upper bound on the systematic uncertainty in the photometric calibration across the sky is 7-12 millimag depending on the bandpass. The systematic uncertainty of the astrometric calibration using the Gaia frame comes from a comparison of the results with Gaia: the standard deviation of the mean and median residuals ($ \Delta ra, \Delta dec $) are (2.3, 1.7) milliarcsec, and (3.1, 4.8) milliarcsec respectively. The Pan-STARRS system and the design of the PS1 surveys are described and an overview of the resulting image and catalog data products and their basic characteristics are described together with a summary of important results. The images, reduced data products, and derived data products from the Pan-STARRS1 surveys are available to the community from the Mikulski Archive for Space Telescopes (MAST) at STScI.

Analysis of CMOS SPAD-based Image Sensors 3

Abstract: SPAD-based solid state CMOS image sensors utilising analogue integrators have attained 11 deep sub electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new 12 method is proposed to determine the read noise in DSERN image sensors by evaluating the peak 13 separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The 14 technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based 15 pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold 16 quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal 17 oversampling techniques are reviewed. 18

Spatially Superposed Pulse Amplitude Modulation Using a Chip-Scale CMOS-Integrated GaN LED Array

Abstract: We present a highly compact system capable of generating discrete optical wireless data signals from logic inputs, suitable for pulse amplitude modulation (PAM) transmission, in visible light communication (VLC).