2,474 research outputs found
A 16×17-SPAD Sensor with Peak Detection for Single-Shot Pulsed-LiDAR
No full textOutdoor LiDAR gets more and more challenging in high background light environments. We propose a novel SPAD chip architecture and an effective background rejection technique enabling single-shot Time-of-Flight LiDAR acquisitions.</jats:p
Towards low timing jitter photon number-resolved Digital Silicon Photomultiplier
No full textWe discuss the design of an innovative general-purpose Digital Silicon Photomultiplier (d-SiPM) with 32 × 32 SPADs, aiming at improving dynamic range and readout timing jitter, by means of a mixed-signal architecture
Linear SPAD array single- and multiple-photon coincidence- based Quantum Random Number Generator
No full textWe presents a 32 × 1 linear Single Photon Avalanche Diode array for quantum communication applications. The array provides the position of the single photon detected, and can identify multiple photon coincidences
Single-Shot Pulsed-LiDAR SPAD Sensor with on-chip Peak Detection for Background Rejection
No full textIn recent years, direct Time-of-Flight techniques have been exploited with single-photon detectors to provide long distance ranges and high-frame rates measurements. Detectors based on Silicon Photon Multipliers commonly collect repetitive laser shots to reconstruct a histogram of the TOF of returning pulsed-laser photons, so to discriminate between signal, background light, and detector noise. Instead of performing multi-shot measurements, we propose a single-shot technique capable to provide just one useful TOF per laser pulse, corresponding to the returning peak signal with the highest number of concurrent photons. In this way, ambient background photons and dark counts are rejected, being mostly randomly distributed over time compared to the laser pulse photons. Therefore, there is no need for repetitive laser shots, neither to acquire and store multiple TOFs, nor to post-process any TOF histogram, since each laser shot can provide the useful distance information. We present a sensor chip based on a pixel with 272 SPADs, which concurrently provide an analog signal to a peak detector triggering a multi-hit TDC each time the number of concurrent photons exceeds the previous peak. We report preliminary tests up to 25 m, rejecting 60 klux solar background, with > 95% single-shot success ratio. copy 1995-2012 IEEE
The chronicle of Alfonson lll and its significance for the historiography of the Asturian kingdom 718-910 AD
No full textThe Asturian kingdom provided the earliest organised
resistance in the Iberian peninsula to the Muslim invaders who overthrew the Visigothic state at the start of the 8th century. Information on the origins of the Asturian kingdom is regrettably sparse. Historians of the kingdom are totally reliant on a late 9th-century cycle of Asturian chronicles associated with the royal court, the most substantial of which is the Chronicle of Alfonso III. This work has survived in two fundamental recensions from the 10th century. Historians' gratitude for its existence is tinged with frustration at its readily apparent weaknesses, such as a chronological imprecision on events and an enigmatic brevity in the commentary.
This thesis considers the 9th-century Asturian chronicles in
the context of their own time. In particular, it examines the Chronicle of Alfonso III not as a disappointing source which fails to yield to modern scholars the information they crave on this obscure period of early Spanish history, but, rather, as an expression of the aims of a medieval author and his copyists. The Chronicle was the product of scarce and valuable resources. Its author, within the limits of his literary ability and source of information, transmitted a message which interacted with the individual understanding of its intended audience. This shift of
emphasis in analysing the Chronicle of Alfonso III rests on the assumption that its original text may be recognised in the later recensions which used it, by addition or omission, as a vehicle for their own interests
Design of a 24×24 SPAD imager for multi-photon coincidence-detection in super resolution microscopy
No full textMicroscopy resolution below the diffraction limit can be achieved by exploiting quantum light properties. NitrogenVacancy (NV) color centers in diamond, dye molecules and quantum dots are examples of single-photon emitters, whose antibunching property allows super-resolution imaging through the measurement of high-order autocorrelation functions. In this work, we present a novel Single Photon Avalanche Diode (SPAD) array architecture optimized for n-fold photon coincidence counting, in each point across the whole sensitive area. It is implemented in a 160 nm Bipolar-CMOS-DMOS (BCD) technology, and it includes 24 × 24 SPAD pixels with 50-μm pixel pitch and 10-μm SPAD diameter. Multi-photon coincidences (within time windows ranging from 2 ns to 500 ns) are identified by post-processing of the in-pixel timing data. Given the expected low photon rate on the detector in quantum imaging applications, on-chip logic discards unwanted information to limit readout throughput and data storage. In fact, reading the whole array would take 3 μs, while skipping rows detecting no photon reduces the readout time to 240 ns in case of no photon detected over the entire array. Moreover, we implemented a multi-gate approach, which avoids halting the array during readout, thus enabling multiple data acquisitions. Thanks to these power-saving expedients and efficient readout, the architecture is scalable towards multiple modules, such as 48 × 48 or 96 × 96-pixel arrays. Finally, it features the possibility of being coupled with a micro-lens array to reach a 78% equivalent fill-factor
Linear SPAD array for quantum communication
No full textQuantum communication is a fast-growing field that takes advantage of the quantum physics laws to protect and secure sensitive data. This work takes part of the European project UNIQORN (Affordable Quantum Communication for Everyone: Revolutionizing the Ecosystem from Fabrication to Application) whose aim is to develop a Quantum System-on-Chip (QSoC) for telecom application. One components of the overall developed systems is an integrated circuit with photodetectors to enable the Quantum Random Number Generator (QRNG) block of the system, tailored to communicate with a non-linear optics circuit to be assembled onto it.
The integrated circuit, fabricated in a BCD 160 nm technology, consists of a 32x1 linear array based on Single-Photon Avalanche-Diode (SPAD) detectors for the generation of a raw random number, by revealing the position on the array of the single photon impinging on it. The linear array architecture consists of 32 pixels, with 125 mu m pitch, each made by 4 SPADs with different diameter (5 mu m, 10 mu m, 20 mu m, and 50 mu m). Two operation modes are implemented: Single-Hit Mode (able to reveal the 5-bit position of the pixel triggered by a single photon, representing a pseudo-random number, in a time window synchronous with the laser emission) and Multi-Hit Mode (used to identify a coincidence of a given number of photons detected within a specified time window)
dTOF SPAD array with Region-Of-Interest selection and dynamic TDC routing
No full textWe present a Single Photon Avalanche Diode (SPAD) array with Region-Of-Interest selection and smart TDC routing, optimized for a direct Time-Of-Flight (dTOF) single-point rangefinder system to be employed on automated assembly lines
Towards low-timing jitter photon number-resolved digital silicon photomultipliers
No full textAn innovative general-purpose Digital Silicon-PhotoMultiplier (dSiPM) with 32 x 32 SPADs, designed in 160 nm BCD technology, is presented. The main goals of this device are to enhance the dynamic range, still keeping the single-photon resolution, and minimize the timing jitter. Both an analog and a digital approach are used to distinguish between 1 to similar to 300 incoming photons. A voltage-controlled current generator converts the pixel's digital output pulse in a current pulse, tunable in amplitude (10 mu A divided by 350 mu A) and duration (from 1 ns to the SPAD holdoff time). The digital option is useful in low photon flux applications. Instead, in high photon flux applications, the digital output misses information, due to an overlap among the photon pulses, so the analog option is to be preferred. Moreover, a double threshold algorithm is implemented in order to reduce the timing jitter of the output. Basically, the concept behind this procedure is to refer the timing measurement to the crossing of the lower threshold, while the higher threshold is only used as a validation for the measurement. Finally, a Time-to-Digital Converter (TDC), with a resolution of 75 ps, is integrated to provide the timing information. The SPAD frontend design works in a free running photon detection modality, and there is the possibility to enable or disable the pixels individually. Thanks to its programmable number of photon resolution and the improved timing performance, the detector can be exploited in many different scientific applications
Alfonso Garcia Valdecasas Garcia Valdecasas - vita e opera
No full textLa presente tesis doctoral tiene por objetivo analizar la obra y el pensamiento de Alfonso Garcia Valdecasas y Garcia Valdecasas. El estudio se encuadra en el área del derecho romano puesto que él comenzó su carrera como iusromanista, doctorándose en Bolonia como colegial del Real Colegio de España con una tesis dirigida por Emilio Costa. Aquel trabajo recibió el premio Vittorio Emanuele Secondo y, tal y como se demostrará, fue el primer trabajo estrictamente científico de la romanística hispana moderna. Otras publicaciones del autor que se incluyen en el presente trabajo permitirán trazar las líneas del pensamiento jurídico, filosófico y –en parte- político de Alfonso Garcia Valdecasas y Garcia Valdecasas.This PhD thesis aims at analyzing both the work and the thought of Alfonso Garcia-Valdecasas Garcia-Valdecasas. The study is in the field of roman law due to the fact that he started his career as a iusromanist, receiving his PhD in Bologna as a collegiate of the Royal Spanish College with a thesis under the supervision of Professor Emilio Costa. That piece received the Vittorio Emanuele II price and, as it will be demonstrated, it represents the first purely scientific work in the modern hispanic roman law science. Other publications by the author included in this very work will allow to outline the traits of the legal, philosophical and -partly- political thought of Alfonso Garcia-Valdecasas Garcia-Valdecasas.Questa tesi di dottorato ha per obbiettivo analizzare l’opera e il pensiero di Alfonso Garcia-Valdecasas y Garcia-Valdecasas. Lo studio si presenta nell’area del diritto romano poiché egli inizió la sua traiettoria come iusromanista, dottorandosi a Bologna come collegiale del Collegio di Spagna, con una tesi diretta da Emilio Costa. Quel lavoro ricevette il Premio Vittorio Emanuele II e, come si mostrerá, rappresenta il primo lavoro prettamente scientifico della romanistica ispanica moderna. Altre pubblicazioni dell’autore incluse nel presente lavoro permetteranno di delineare i tratti del pensiero giuridico, filosofico e –in parte- político di Alfonso Garcia Valdecasas y Garcia Valdecasas
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