Mineki Soga

A 100-m Range 10-Frame/s 340

This paper introduces a single-photon detection technique for time-of-flight distance ranging based on the temporal and spatial correlation of photons. A proof-of-concept prototype achieving depth imaging up to 100 meters with a resolution of 340 × 96 pixels at 10 frames/s was implemented. At the core of the system, a sensor chip comprising 32 macro-pixels based on an array of single-photon avalanche diodes featuring an optical fill factor of 70% was fabricated in a 0.18-μm CMOS. The chip also comprises an array of 32 circuits capable of generating precise triggers upon correlation events as well as of sampling the number of photons involved in each correlation event, and an array of 32 12-b time-to-digital converters. Characterization of the TDC array led to -0.52 LSB and 0.73 LSB of differential and integral nonlinearities, respectively. Quantitative evaluation of the TOF sensor under strong solar background light, i.e., 80 klux, revealed a repeatability error better than 10 cm throughout the distance range of 100 m, thus leading to a relative precision of 0.1%. In the same condition, the relative nonlinearity error was 0.37%. In order to show the suitability of our approach in a real-world situation, experimental results in which the depth sensor was operated in a typical traffic scenario are also reported.

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We introduce an optical time-of-flight image sensor taking advantage of a MEMS-based laser scanning device. Unlike previous approaches, our concept benefits from the high timing resolution and the digital signal flexibility of single-photon pixels in CMOS to allow for a nearly ideal cooperation between the image sensor and the scanning device. This technique enables a high signal-to-background light ratio to be obtained, while simultaneously relaxing the constraint on size of the MEMS mirror. These conditions are critical for devising practical and low-cost depth sensors intended to operate in uncontrolled environments, such as outdoors. A proof-of-concept prototype capable of operating in real-time was implemented. This paper focuses on the design and characterization of a 256 x 64-pixel image sensor, which also comprises an event-driven readout circuit, an array of 64 row-level high-throughput time-to-digital converters, and a 16 Gbit/s global readout circuit. Quantitative evaluation of the sensor under 2 klux of background light revealed a repeatability error of 13.5 cm throughout the distance range of 20 meters.

96-Pixel Time-of-Flight Depth Sensor in 0.18-

With the emerging need for high-resolution light detection and ranging (LIDAR) technologies in advanced driver assistance systems (ADAS), we introduce a system-on-a-chip (SoC) that performs time-correlated single-photon counting and complete digital signal processing for a time-of-flight (TOF) sensor. At the core of the 0.18-μm CMOS SoC, we utilize linear arrays of 16 TOF and 32 intensity-only macro-pixels based on single-photon avalanche diodes in an original look-ahead concept, thus acquiring active TOF and passive intensity images simultaneously. The SoC also comprises an array of circuits capable of generating precise triggers upon spatiotemporal correlation events, an array of 64 12-b time-to-digital converters, and 768 kb of SRAM memory. The SoC provides the system-level electronics with a serial and low-bit-rate digital interface for: 1) multi-echo distance; 2) distance reliability; 3) intensity; and 4) passive-only intensity, thus mitigating system-level complexity and cost. A proof-of-concept prototype that achieves depth imaging up to 100 m with a resolution of 202 × 96 pixels at 10 frames/s has been implemented. Quantitative evaluation of the TOF sensor under strong solar background illuminance, i.e., 70 klux, revealed a repeatability error of 14.2 cm throughout the distance range of 100 m, thus leading to a relative precision of 0.14%. Under the same conditions, the relative nonlinearity error was 0.11%. In order to show the suitability of our approach for ADAS-related applications, experimental results in which the depth sensor was operated in typical traffic situations have also been reported.

\mu\hbox{m}

We have developed a prototype of a compact integrated visual sensor which detects direction and velocity of motion on a focal plane in a wide brightness range in real time with a newly devised motion measurement method. The sensor is composed of a lens and a single-chip very large scale integration whose die size is 2 mm /spl times/ 2 mm that was fabricated with a 1.5-/spl mu/ standard CMOS process. The spatial resolution is 10 /spl times/ 2. As a result of performance evaluation of the prototype sensor, it was confirmed that the sensor can detect motion direction and velocity up to an on-chip image velocity of 100 mm/s in a response time of 10 /spl mu/s under an illuminance range between 100 and 100,000 lux. Furthermore, we have demonstrated effectiveness of the visual sensor by applying the sensor to running vehicle detection on a road and blind-corner monitoring at a road junction.

CMOS

This paper considers pedestrian detection, specialized for a near infrared imaging system at night. The main objective is the detection of a distant pedestrian, beyond an illuminated area in a low-beam mode, using a monocular on-board camera. In this method, the region of interest (ROI) is first selected by extracting bright regions, and shape information from a whole human body, is later used for verification. Motion information is not used, due to difficulties in cancellation of ego-motion. The ROI selector is implemented by a modified boosted cascade, in combination with dynamic perspective constraints. After filtering out typical non-pedestrian objects, the remaining ROIs are verified using a support vector machine (SVM). The verified ROIs are tracked with a simple alpha-beta tracker, in combination with final validation, based on a classification score from the SVM. The effectiveness of the proposed modules has been confirmed using several typical night time scenarios.

Design and characterization of a 256x64-pixel single-photon imager in CMOS for a MEMS-based laser scanning time-of-flight sensor

This paper reports on a light detection and ranging (LIDAR) system that incorporates a microelectromechanical-system (MEMS) mirror scanner and a single-photon imager. The proposed architecture enables a high signal-to-background ratio due to pixel-level synchronization of the single-photon imager and the MEMS mirror. It also allows the receiving optics to feature a large aperture, yet utilizing a small MEMS device. The MEMS actuator achieves a mechanical scanning amplitude of ±4° horizontally and ±3° vertically, while the field of view of the overall sensor is 45 by 110. Distance images were acquired outdoors in order to qualitatively evaluate our sensor imaging capabilities. Quantitative ranging performance characterization carried out under 10 klx of ambient light revealed a precision of 14.5 cm throughout the distance range to 25 m, thus leading to a relative precision of 0.58%.

A 0.18-

This paper presents a method of pedestrian detection for automobile applications, based on stereo vision. Vision based pedestrian detection presents a difficulty due to the diversity of appearances. The proposed method overcomes the difficulty mainly through the following two contributions. Firstly, employing four directional features with the classifier increases the robustness against small affine deformation of objects. Secondly, by merging classification and tracking, robustness against temporal change of appearance is improved when considering temporal continuity of classification score. The experiments, performed on approximately 16 minutes of video sequences, confirmed that the method can detect pedestrians with low false detection.

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This paper introduces a low-noise single-photon sensor in a 0.18μm CMOS technology for scanning-based coaxial optical rangefinders. At the core of the sensor, macro pixels consisting of 10×10 single-photon detectors enable time-of-flight measurements by taking advantage of temporal and spatial correlations. Unlike conventional silicon photo-multipliers, or multi-pixel photon counters, our sensor features a pulse-shaping and summing stage that accurately resolves the number of quasi-simultaneous photon detections. Sensor characterization data are reported. When mounted on a practical rangefinder setup, the sensor enables distance measurements up to 50 meters with 1σ repeatability error lower than 26cm throughout the range, using 10 laser pulses.

m CMOS SoC for a 100-m-Range 10-Frame/s 200

A CMOS single-photon detector, including a highly miniaturized active recharge circuit, achieving the highest counting rate yet reported for an afterpulsing-free Geiger-mode photodiode is introduced. Thanks to its low-noise and 6-ns dead time figure, a dynamic-range of 116dB for steady-state photon counting in a single acquisition time of 20ms was achieved.

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A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm.