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13 pages, 8269 KB

Open AccessArticle

Design and Characterization of a Prototype Pixel Readout Chip for Synchrotron Single Photon-Counting Detectors with 50 µm Pitch and 20 e⁻rms ENC Noise

by Shijie Lu, Yifan Jiang, Tao Sun, Fuwan Gan, Tianyang Wang and Zhen Sheng

Sensors 2026, 26(10), 2992; https://doi.org/10.3390/s26102992 - 9 May 2026

Viewed by 1265

Abstract

As synchrotron radiation sources (SRSs) expand to cover a broader energy range, the demand for hybrid detectors with improved spatial and energy resolution is increasing. This paper presents the design and characterization of a prototype pixel readout ASIC featuring a small pixel size and low noise, developed for low energy soft X-ray applications. This chip adopts the single photon-counting (SPC) approach and each pixel consists of a front-end amplifier, a discriminator, a charge injection circuitry and a pair of 15-bit counters with associated logic. Fabricated in a 130 nm CMOS process, the chip integrates a 2 × 16 pixel matrix with a 50 µm ×50 µm pixel size. Measurement results indicate the maximum pixel equivalent noise charge (ENC) across the matrix is 20 e⁻rms without sensor attached. The results validate that the chip design has the potential to deliver a low-energy resolution for soft X-ray applications. Full article

(This article belongs to the Section Electronic Sensors)

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28 pages, 5568 KB

Open AccessArticle

Research on Low-Altitude Aircraft Point Cloud Generation Method Using Single Photon Counting Lidar

by Zhigang Su, Shaorui Liang, Jingtang Hao and Bing Han

Photonics 2025, 12(3), 205; https://doi.org/10.3390/photonics12030205 - 27 Feb 2025

Cited by 1 | Viewed by 1138

Abstract

To address the deficiency of aircraft point cloud training data for low-altitude environment perception systems, a method termed APCG (aircraft point cloud generation) is proposed. APCG can generate aircraft point cloud data in the single photon counting Lidar (SPC-Lidar) system based on information such as aircraft type, position, and attitude. The core of APCG is the aircraft depth image generator, which is obtained through adversarial training of an improved conditional generative adversarial network (cGAN). The training data of the improved cGAN are composed of aircraft depth images formed by spatial sampling and transformation of fine point clouds of 76 types of aircraft and 4 types of drone. The experimental results demonstrate that APCG is capable of efficiently generating diverse aircraft point clouds that reflect the acquisition characteristics of the SPC-Lidar system. The generated point clouds exhibit high similarity to the standard point clouds. Furthermore, APCG shows robust adaptability and stability in response to the variation in aircraft slant range. Full article

(This article belongs to the Special Issue Recent Progress in Single-Photon Generation and Detection)

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31 pages, 7519 KB

Open AccessReview

Modeling for Single-Photon Avalanche Diodes: State-of-the-Art and Research Challenges

by Xuanyu Qian, Wei Jiang, Ahmed Elsharabasy and M. Jamal Deen

Sensors 2023, 23(7), 3412; https://doi.org/10.3390/s23073412 - 24 Mar 2023

Cited by 24 | Viewed by 15445

Abstract

With the growing importance of single-photon-counting (SPC) techniques, researchers are now designing high-performance systems based on single-photon avalanche diodes (SPADs). SPADs with high performances and low cost allow the popularity of SPC-based systems for medical and industrial applications. However, few efforts were put into the design optimization of SPADs due to limited calibrated models of the SPAD itself and its related circuits. This paper provides a perspective on improving SPAD-based system design by reviewing the development of SPAD models. First, important SPAD principles such as photon detection probability (PDP), dark count rate (DCR), afterpulsing probability (AP), and timing jitter (TJ) are discussed. Then a comprehensive discussion of various SPAD models focusing on each of the parameters is provided. Finally, important research challenges regarding the development of more advanced SPAD models are summarized, followed by the outlook for the future development of SPAD models and emerging SPAD modeling methods. Full article

(This article belongs to the Special Issue Recent Advances in CMOS Image Sensor)

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22 pages, 5522 KB

Open AccessReview

Single Photon Avalanche Diode Arrays for Time-Resolved Raman Spectroscopy

by Francesca Madonini and Federica Villa

Sensors 2021, 21(13), 4287; https://doi.org/10.3390/s21134287 - 23 Jun 2021

Cited by 37 | Viewed by 10502

Abstract

The detection of peaks shifts in Raman spectroscopy enables a fingerprint reconstruction to discriminate among molecules with neither labelling nor sample preparation. Time-resolved Raman spectroscopy is an effective technique to reject the strong fluorescence background that profits from the time scale difference in the two responses: Raman photons are scattered almost instantaneously while fluorescence shows a nanoseconds time constant decay. The combination of short laser pulses with time-gated detectors enables the collection of only those photons synchronous with the pulse, thus rejecting fluorescent ones. This review addresses time-gating issues from the sensor standpoint and identifies single photon avalanche diode (SPAD) arrays as the most suitable single-photon detectors to be rapidly and precisely time-gated without bulky, complex, or expensive setups. At first, we discuss the requirements for ideal Raman SPAD arrays, particularly focusing on the design guidelines for optimized on-chip processing electronics. Then we present some existing SPAD-based architectures, featuring specific operation modes which can be usefully exploited for Raman spectroscopy. Finally, we highlight key aspects for future ultrafast Raman platforms and highly integrated sensors capable of undistorted identification of Raman peaks across many pixels. Full article

(This article belongs to the Special Issue Women in Sensors)

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15 pages, 1319 KB

Open AccessArticle

Unusual Fluorescence Behavior of Pyrene-Amine Containing Dendrimers

by Andrea Ruiu, Mireille Vonlanthen, Sandra M. Rojas-Montoya, Israel González-Méndez and Ernesto Rivera

Molecules 2019, 24(22), 4083; https://doi.org/10.3390/molecules24224083 - 12 Nov 2019

Cited by 11 | Viewed by 3500

Abstract

A new class of pyrene-based dendrimers, characterized by the presence of a 1,4,7,10-Tetraazacyclododecane (cyclen) unit as the core, was studied by SSF (steady-state fluorescence) and SPC (single-photon counting fluorescence). The photophysical behavior of these dendrimers was studied in THF, DMF and DMSO solution. The typical signals for pyrene-labeled molecules were recorded in each solvent, showing the representative fluorescence spectra: the corresponding emissions of monomer and excimer of the pyrene chromophore are observed. Unexpectedly, the typical quenching of tertiary amine on the pyrene emission was not observed in these dendrimers. Quenching studies were performed by adding up to 3 equivalents of trifluoroacetic acid (TFA). To our knowledge, this is the first report of pyrene’s unquenching behavior by a tertiary amine. Full article

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16 pages, 26646 KB

Open AccessArticle

High Dynamic Range Imaging at the Quantum Limit with Single Photon Avalanche Diode-Based Image Sensors

by Neale A.W. Dutton, Tarek Al Abbas, Istvan Gyongy, Francescopaolo Mattioli Della Rocca and Robert K. Henderson

Sensors 2018, 18(4), 1166; https://doi.org/10.3390/s18041166 - 11 Apr 2018

Cited by 42 | Viewed by 11513

Abstract

This paper examines methods to best exploit the High Dynamic Range (HDR) of the single photon avalanche diode (SPAD) in a high fill-factor HDR photon counting pixel that is scalable to megapixel arrays. The proposed method combines multi-exposure HDR with temporal oversampling in-pixel. We present a silicon demonstration IC with 96 × 40 array of 8.25 µm pitch 66% fill-factor SPAD-based pixels achieving >100 dB dynamic range with 3 back-to-back exposures (short, mid, long). Each pixel sums 15 bit-planes or binary field images internally to constitute one frame providing 3.75× data compression, hence the 1k frames per second (FPS) output off-chip represents 45,000 individual field images per second on chip. Two future projections of this work are described: scaling SPAD-based image sensors to HDR 1 MPixel formats and shrinking the pixel pitch to 1–3 µm. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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17 pages, 3125 KB

Open AccessArticle

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

by Neale A. W. Dutton, Istvan Gyongy, Luca Parmesan and Robert K. Henderson

Sensors 2016, 16(7), 1122; https://doi.org/10.3390/s16071122 - 20 Jul 2016

Cited by 34 | Viewed by 17720

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. Full article

(This article belongs to the Special Issue Photon-Counting Image Sensors)

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