- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Compact Real-Time Inter-Frame Histogram Builder for 15Bits High-Speed ToF-Imagers based on Single-Photon Detection
摘要： Time-of-flight image sensors based on single-photon detection, i.e. SPADs, require some filtering of pixel readings. Accurate depth measurements are only possible if the jitter of the detector is mitigated. Moreover, the time stamp needs to be effectively separated from uncorrelated noise such as dark counts and background illumination. A powerful tool for this is building a histogram of a number of pixel readings. Future generation of ToF imagers are seeking to increase spatial and temporal resolution along with the dynamic range and frame rate. Under these circumstances, storing the complete histogram for every pixel becomes practically impossible. Considering that most of the information contained by the histogram represents noise, we propose a highly efficient method to store just the relevant data required for ToF computation. This method makes use of the shifted inter-frame histogram (SifH). It requires a memory as low as 128 times smaller than storing the complete histogram if the pixel values are coded on up to 15 bits. Moreover, a fixed 28 words memory is enough to process histograms containing up to 215 bins. In exchange, the overall frame rate only decreases to one half. The hardware implementation of this algorithm is presented. Its remarkable robustness for a low SNR of the ToF estimation is demonstrated by Matlab simulations and FPGA implementation using input data from a SPAD camera prototype.
关键词： shifted inter-frame histogram (SifH),single-photon avalanche-diode (SPAD),real-time time-of-flight (ToF) estimation,ToF image sensor
更新于2025-09-23 15:22:29
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Background Light Rejection in SPAD-Based LiDAR Sensors by Adaptive Photon Coincidence Detection
摘要： Light detection and ranging (LiDAR) systems based on silicon single-photon avalanche diodes (SPAD) offer several advantages, like the fabrication of system-on-chips with a co-integrated detector and dedicated electronics, as well as low cost and high durability due to well-established CMOS technology. On the other hand, silicon-based detectors suffer from high background light in outdoor applications, like advanced driver assistance systems or autonomous driving, due to the limited wavelength range in the infrared spectrum. In this paper we present a novel method based on the adaptive adjustment of photon coincidence detection to suppress the background light and simultaneously improve the dynamic range. A major disadvantage of fixed parameter coincidence detection is the increased dynamic range of the resulting event rate, allowing good measurement performance only at a specific target reflectance. To overcome this limitation we have implemented adaptive photon coincidence detection. In this technique the parameters of the photon coincidence detection are adjusted to the actual measured background light intensity, giving a reduction of the event rate dynamic range and allowing the perception of high dynamic scenes. We present a 192 × 2 pixel CMOS SPAD-based LiDAR sensor utilizing this technique and accompanying outdoor measurements showing the capability of it. In this sensor adaptive photon coincidence detection improves the dynamic range of the measureable target reflectance by over 40 dB.
关键词： system-on-chip (SoC),single-photon avalanche diode (SPAD),CMOS,light detection and ranging (LiDAR),time-of-flight (TOF),background light rejection
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Nantes, France (2018.9.24-2018.9.27)] 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Bluetooth-Based Indoor Positioning Through ToF and RSSI Data Fusion
摘要： After several decades of both market and scientific interest, indoor positioning is still a hot and not completely solved topic, fostered by the advancement of technology, pervasive market penetration of mobile devices and novel communication standards. In this work, we propose a two-step model-based indoor positioning algorithm based on Bluetooth Low-Energy, a pervasive and energy efficient standard protocol. In the first (i.e. ranging) step a Kalman Filter (KF) performs the fusion of both RSSI and Time-of-Flight measurement data. Thus, we demonstrate the benefit of not relying only on RSSI, comparing ranging performed with or without the help of ToF. In the second (i.e. positioning) step, the distance estimates from multiple anchors are combined into a quadratic cost function, which is minimized to determine the coordinates of the target node in a planar reference frame. The proposed solution is tailored to reduce the computational effort and target real-time execution on an embedded platform, demonstrating a limited loss of performance. The paper presents an experimental setup and discusses meaningful results, demonstrating a robust BLE-based indoor positioning solution for embedded systems.
关键词： Time-of-Flight (ToF),Bluetooth Low Energy,Indoor positioning,data fusion,Kalman filter
更新于2025-09-23 15:21:21
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[IEEE ESSCIRC 2019 - IEEE 45th European Solid State Circuits Conference (ESSCIRC) - Cracow, Poland (2019.9.23-2019.9.26)] ESSCIRC 2019 - IEEE 45th European Solid State Circuits Conference (ESSCIRC) - A 19-GHz Pulsed-Coherent ToF Receiver With 40-??m Precision for Laser Ranging Systems
摘要： This letter presents a pulsed-coherent time-of-flight (ToF) receiver for a laser ranging system implemented in 28-nm CMOS process. The prototype is designed at 19-GHz carrier frequency with 6.8-ns pulsed modulation. A segmented coarse-fine ToF measurement is adopted to achieve high resolution and fast acquisition. The coarse ToF is recorded by detecting the pulse’s edge whereas the fine measurement is measured by coherent detection. The proposed post-edge detection with automatic gain control loop provides better suppression of walk error from 600 to 26 ps as compared to the rising-edge detection. Also, phase-invariant variable-gain amplifiers provide a low phase error of < ±1? across gain settings with 60-dB dynamic range. This letter can, based on the timing accuracy, achieve 40-μm precision with 1-MHz sampling rate.
关键词： Lidar,time-of-flight (ToF),pulsed coherent,phase-invariant amplifier,walk error
更新于2025-09-23 15:19:57
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An 80 x 25 Pixel CMOS Single-Photon Sensor With Flexible On-Chip Time Gating of 40 Subarrays for Solid-State 3-D Range Imaging
摘要： A CMOS solid-state 3-D range imager that uses short (～110 ps) laser pulses and a novel flexible time gating scheme for a single-photon avalanche diode (SPAD) array is presented. The array is divided into 40 subarrays for which a narrow (<0.8 ns) time gating position can be set and scanned independently. The imager can be set to measure multiple regions of interest by means of the flexible time gating of the subarrays. The time gating for each of the subarrays is selected separately with an on-chip delay-locked loop (DLL) block that has 240 outputs and a delay grid of ～100 ps. The prototype has 80 × 25 pixels overall with 10 × 5 pixel subarrays. The fill factor of the sensor area is 32%. A 3-D range image is demonstrated at ～10 frames/s with centimeter-level precision in the case of passive targets within a range of ～4 m and a field of view of 18° × 28°, requiring an average active illumination power of only 0.1 mW.
关键词： time gating,3-D imager,SPAD array,single-photon avalanche diode (SPAD),time-of-flight (TOF)
更新于2025-09-19 17:15:36
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Recoil-ion momentum spectroscopy for cold rubidium in a strong femtosecond laser field
摘要： In this study, a new magneto-optical trap (MOT) recoil ion momentum spectrometer is built for investigating the interactions between cold rubidium (Rb) atoms and strong laser fields. This compact device can provide cold Rb in three different modes: 2D MOT mode, in which the beam generated by a two-dimensional MOT is pushed directly to the interaction regime; molasses mode, in which cooling lasers are applied at the interaction regime; and 3D MOT mode, in which a quadrupole magnetic field is applied to form a three-dimensional MOT. The typical densities of the three target modes are estimated to be 107, 108, and 109 atoms/cm3, respectively. Switching between the target modes is expected to provide a broad range of laser intensities with reasonable count rates while avoiding space charge effects. A single photoionization experiment serves as a benchmark test of the recoil ion momentum resolution. The best resolution is estimated as an unprecedented 0.12 a.u. in the time-of-flight direction, demonstrating significant potential for strong field ionization dynamics using this technique.
关键词： Ionization and excitation processes,Instrumentation and methods for time-of-flight (TOF) spectroscopy
更新于2025-09-11 14:15:04
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A 19-GHz Pulsed-Coherent ToF Receiver With 40-$\mu$ m Precision for Laser Ranging Systems
摘要： This letter presents a pulsed-coherent time-of-flight (ToF) receiver for a laser ranging system implemented in 28-nm CMOS process. The prototype is designed at 19-GHz carrier frequency with 6.8-ns pulsed modulation. A segmented coarse-fine ToF measurement is adopted to achieve high resolution and fast acquisition. The coarse ToF is recorded by detecting the pulse’s edge whereas the fine measurement is measured by coherent detection. The proposed post-edge detection with automatic gain control loop provides better suppression of walk error from 600 to 26 ps as compared to the rising-edge detection. Also, phase-invariant variable-gain amplifiers provide a low phase error of < ±1° across gain settings with 60-dB dynamic range. This letter can, based on the timing accuracy, achieve 40-μm precision with 1-MHz sampling rate.
关键词： Lidar,time-of-flight (ToF),phase-invariant amplifier,walk error,pulsed coherent
更新于2025-09-11 14:15:04
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A New Analytical Charge Transfer Model for Time-of-Flight Image Sensors
摘要： A powerful tool for analyzing the performances of an image sensor designed for time-of-flight measurement purposes, the impulse response measurement (IRM), is presented. A way to measure the charges diffusion time (time for the photogenerated charges to be collected by the photodiode) using the analysis of an IRM is given. An unexpected phenomenon that occurs when performing a specific IRM is then showcased: performing two successive transfers, a short duration one followed by a long duration one is actually less efficient than performing a single transfer of long duration (same duration as the second transfer in the first case). Accordingly, a mathematical sufficient condition on the charge transfer efficiency function (CTEF) is enounced. A physical modeling based on thermionic emission theory and the influence of the potential barrier’s width on its effective height is presented. The model leads to a new CTEF expression that fulfills the mathematical requirement. Finally, a numerical simulation with the new CTEF fitting the experimental IRM data is performed.
关键词： time-of-flight (TOF),thermionic emission theory,Dirac-light pulse (DLP),diffusion time,impulse response measurement (IRM),Charge transfer efficiency function (CTEF),CMOS image sensor (CIS),light image detection and ranging (LIDAR),sense node (SN)
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Nantes (2018.9.24-2018.9.27)] 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - An Analytical Study of Time of Flight Error Estimation in Two-Way Ranging Methods
摘要： In absence of clock synchronization, Two-Way Ranging (TWR) is the most commonly used technique for measuring the distance between two wireless transceivers. The existing time-of-flight (TOF) error estimation model, the IEEE 802.15.4-2011 standard, is specifically based on clock drift error. However, it is insufficient when an in-depth comparative analysis of different TWR methods is required. In this paper, we propose an extended TOF error estimation model for TWR methods, based on the IEEE 802.15.4 standard. Using the proposed model, we perform an analytical study of TOF error estimation among different TWR methods. The model is validated with numerical simulation results. Moreover, we demonstrate the pitfalls of the symmetric double-sided TWR (SDS-TWR) method, which is commonly used to reduce the TOF error due to clock drifts.
关键词： two way ranging (TWR),time of flight (TOF),time of arrival (TOA),TOF error model,analytical model,indoor positioning,time based ranging techniques
更新于2025-09-04 15:30:14
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SPAD-Based LiDAR Sensor in 0.35 μm Automotive CMOS with Variable Background Light Rejection
摘要： We present a SPAD-based LiDAR sensor fabricated in an automotive certified 0.35 μm CMOS process. Since reliable sensor operation in high ambient light environment is a crucial factor in automotive applications, four SPADs are implemented in each pixel to suppress ambient light by the detection of photon coincidences. By pixel individual adjustment of the coincidence parameters to the present ambient light condition, an almost constant measurement performance is achieved for a wide range of different target reflectance and ambient illumination levels. This technique allows the acquisition of high dynamic range scenes in a single laser shot. For measurement and demonstration purpose a LiDAR camera with the developed sensor has been built.
关键词： time-of-flight (TOF),background rejection,single-photon avalanche diode (SPAD),range imaging,light detection and ranging (LiDAR),photon coincidence
更新于2025-09-04 15:30:14