X-ray photon correlation spectroscopy (XPCS) provides an opportunity to study the dynamics of systems by measuring the temporal fluctuations in a far-field diffraction pattern. A two-dimensional detector system has been developed to investigate fluctuations in the frequency range of several Hz to kHz. The X-ray detector system consists of a thin 100 microm scintillation crystal coupled to a Geiger-mode avalanche photodiode array. In this article the elements of the system are detailed and the detector for XPCS measurements is demonstrated.
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http://dx.doi.org/10.1107/S0909049508034365 | DOI Listing |
We present experimental results of Ge-on-Si single-photon avalanche diodes based on a novel, to our knowledge, double mesa structure. Using this structure, the electric field at the mesa edges is suppressed compared to a traditional single mesa, leading to significant performance improvements. The dark current in linear mode shows a smaller increase for larger reverse voltages, resulting in a reduction by more than 260 times at low temperatures.
View Article and Find Full Text PDFWe consider avalanche photodiodes (APDs) functioning under near Geiger-mode operation for extremely weak light (single or several photons) detection, such as in LiDAR receivers. To meet such demands, APDs which simultaneously have a large active window size, moderate bandwidth (∼GHz), and high internal gain (responsivity), are highly desired. However, it is difficult to design APDs capable of meeting the afore-mentioned performance requirements due to the intrinsic limitations of the gain-bandwidth product (GBP).
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October 2024
Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore, 117543, Singapore.
Sensors (Basel)
September 2024
National Key Laboratory of Laser Spatial Information, Institute of Opto-Electronic, Harbin Institute of Technology, Harbin 150001, China.
The photon-counting light laser detection and ranging (LiDAR), especially the Geiger mode avalanche photon diode (Gm-APD) LiDAR, can obtain three-dimensional images of the scene, with the characteristics of single-photon sensitivity, but the background noise limits the imaging quality of the laser radar. In order to solve this problem, a depth image estimation method based on a two-dimensional (2D) Kaniadakis entropy thresholding method is proposed which transforms a weak signal extraction problem into a denoising problem for point cloud data. The characteristics of signal peak aggregation in the data and the spatio-temporal correlation features between target image elements in the point cloud-intensity data are exploited.
View Article and Find Full Text PDFSensors (Basel)
August 2024
Department of Health Sciences, "Magna Graecia" University, 88100 Catanzaro, Italy.
Single-photon avalanche diodes (SPADs) belong to a family of avalanche photodiodes (APDs) with single-photon detection capability that operate above the breakdown voltage (i.e., Geiger mode).
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