Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness

Bronchiectasis in India:results from the European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) and Respiratory Research Network of India Registry

BACKGROUND: Bronchiectasis is a common but neglected chronic lung disease. Most epidemiological data are limited to cohorts from Europe and the USA, with few data from low-income and middle-income countries. We therefore aimed to describe the characteristics, severity of disease, microbiology, and treatment of patients with bronchiectasis in India. METHODS: The Indian bronchiectasis registry is a multicentre, prospective, observational cohort study. Adult patients ( 6518 years) with CT-confirmed bronchiectasis were enrolled from 31 centres across India. Patients with bronchiectasis due to cystic fibrosis or traction bronchiectasis associated with another respiratory disorder were excluded. Data were collected at baseline (recruitment) with follow-up visits taking place once per year. Comprehensive clinical data were collected through the European Multicentre Bronchiectasis Audit and Research Collaboration registry platform. Underlying aetiology of bronchiectasis, as well as treatment and risk factors for bronchiectasis were analysed in the Indian bronchiectasis registry. Comparisons of demographics were made with published European and US registries, and quality of care was benchmarked against the 2017 European Respiratory Society guidelines. FINDINGS: From June 1, 2015, to Sept 1, 2017, 2195 patients were enrolled. Marked differences were observed between India, Europe, and the USA. Patients in India were younger (median age 56 years [IQR 41-66] vs the European and US registries; p<0\ub70001]) and more likely to be men (1249 [56\ub79%] of 2195). Previous tuberculosis (780 [35\ub75%] of 2195) was the most frequent underlying cause of bronchiectasis and Pseudomonas aeruginosa was the most common organism in sputum culture (301 [13\ub77%]) in India. Risk factors for exacerbations included being of the male sex (adjusted incidence rate ratio 1\ub717, 95% CI 1\ub703-1\ub732; p=0\ub7015), P aeruginosa infection (1\ub729, 1\ub710-1\ub750; p=0\ub7001), a history of pulmonary tuberculosis (1\ub720, 1\ub707-1\ub734; p=0\ub7002), modified Medical Research Council Dyspnoea score (1\ub732, 1\ub725-1\ub739; p<0\ub70001), daily sputum production (1\ub716, 1\ub703-1\ub730; p=0\ub7013), and radiological severity of disease (1\ub703, 1\ub701-1\ub704; p<0\ub70001). Low adherence to guideline-recommended care was observed; only 388 patients were tested for allergic bronchopulmonary aspergillosis and 82 patients had been tested for immunoglobulins. INTERPRETATION: Patients with bronchiectasis in India have more severe disease and have distinct characteristics from those reported in other countries. This study provides a benchmark to improve quality of care for patients with bronchiectasis in India. FUNDING: EU/European Federation of Pharmaceutical Industries and Associations Innovative Medicines Initiative inhaled Antibiotics in Bronchiectasis and Cystic Fibrosis Consortium, European Respiratory Society, and the British Lung Foundation

Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms.

Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings

Direct time-of-flight SPAD image sensors for light detection and ranging

Depth sensing is an increasingly important feature in many applications of consumer, automotive, augmented/virtual reality (AR-VR), space and bio-medical imaging. Long range, high depth resolution, high spatial resolution, and high frame rates are often conflicting requirements and difficult to be simultaneously achieved due to extreme operating conditions. Direct time-of-flight (DTOF) has evolved to becoming a powerful technique to perform light detection and ranging (LiDAR). Thanks to advances in low-jitter optical detectors, such as single-photon avalanche diodes (SPADs), and accurate chronometers like time-to-digital converters (TDCs), picosecond timing resolution is possible, thus enabling millimetric depth resolutions. High ambient light is an inevitable challenge in LiDAR applications, whose levels may exceed up to 100 klux on a bright sunny day, making it particularly challenging to detect a target submerged within an overwhelming noise floor. High ambient light operation can be accommodated by means of optical filtering, a higher laser power or temporal filtering techniques. Optical filtering is often restricted to a narrow, 10-50 nm bandwidth, insufficient at high ambient light levels. Higher laser power is not always possible, due to eye safety regulations and power constraints. Temporal filtering such as time gating and coincidence detection can thus be powerful tools to cope with high ambient light. This thesis focuses on the design of DTOF sensors for LiDAR. To that end, two SPAD-based DTOF sensors are designed. The first sensor is designed in a 3D-stacked 45/65 nm CMOS technology, thus, enabling a modular architecture where the module itself comprises of 8x16 pixels. With a 60 ps-resolution TDC at its core, the sensor provides centimetric accuracy up to 300 m range in free space. The second sensor, named Jatayu, advances the previous design by hosting 256x128 pixels, thereby, significantly improving on its spatial resolution. While retaining its modularity, Jatayu also enables multi-level coincidence detection and progressive time-gating to suppress background light. To the best of the authorâs knowledge, progressive gating has been implemented in a LiDAR for the first time in this thesis. Designed in a 3D-stacked 45/22 nm CMOS technology, the sensor achieves under 7 cm accuracy over 100 m ranging and 10 klux background light. With its capability of acquiring 128£128, 3D depth maps of high dynamic range scenes, Jatayu is highly suitable for a variety of imaging applications in many different scenarios

Modeling and Analysis of a Direct Time-of-Flight Sensor Architecture for LiDAR Applications

Direct time-of-flight (DTOF) is a prominent depth sensing method in light detection and ranging (LiDAR) applications. Single-photon avalanche diode (SPAD) arrays integrated in DTOF sensors have demonstrated excellent ranging and 3D imaging capabilities, making them promising candidates for LiDARs. However, high background noise due to solar exposure limits their performance and degrades the signal-to-background noise ratio (SBR). Noise-filtering techniques based on coincidence detection and time-gating have been implemented to mitigate this challenge but 3D imaging of a wide dynamic range scene is an ongoing issue. In this paper, we propose a coincidence-based DTOF sensor architecture to address the aforementioned challenges. The architecture is analyzed using a probabilistic model and simulation. A flash LiDAR setup is simulated with typical operating conditions of a wide angle field-of-view (FOV = 40 ° ) in a 50 klux ambient light assumption. Single-point ranging simulations are obtained for distances up to 150 m using the DTOF model. An activity-dependent coincidence is proposed as a way to improve imaging of wide dynamic range targets. An example scene with targets ranging between 8–60% reflectivity is used to simulate the proposed method. The model predicts that a single threshold cannot yield an accurate reconstruction and a higher (lower) reflective target requires a higher (lower) coincidence threshold. Further, a pixel-clustering scheme is introduced, capable of providing multiple simultaneous timing information as a means to enhance throughput and reduce timing uncertainty. Example scenes are reconstructed to distinguish up to 4 distinct target peaks simulated with a resolution of 500 ps. Alternatively, a time-gating mode is simulated where in the DTOF sensor performs target-selective ranging. Simulation results show reconstruction of a 10% reflective target at 20 m in the presence of a retro-reflective equivalent with a 60% reflectivity at 5 m within the same FOV

Direct time-of-flight depth sensor architecture and method for operating of such a sensor

The present invention relates to a direct time-of-flight depth imaging sensor comprising: an array of photodetectors (43) arranged in one or more subgroups (41), wherein each subgroup (41) is divided into a plurality of minigroups (42) of photodetectors (43); digital processing and communication units (63) each associated to one of the minigroups (42), each comprising: a minigroup pixel address register (69) to store an address of the photodetector (43) in the respective minigroup (42) which has detected the last photon detection event within a coincidence window, wherein the coincidence window corresponds to detection window of a fixed duration starting with the first photon detection event within the respective subgroup (41); and a minigroup timestamp unit (68) configured to store minigroup timestamp data of the last photon detection event received in the coincidence window; a time to digital converter (61) configured to generate a subgroup timestamp data about the first photon detection event in the subgroup (41) during the coincidence window

Photon detecting 3d imaging sensor device

The invention relates to a photon detecting 3D imaging sensor device for detecting a distance information for pixels in an image, comprising: - an array of detector units, wherein each detector unit is configured to receive a light signal pulse and to provide a detection signal pulse on receipt of a light signal pulse; - a pulse selection unit including a decision tree with one or more stages, wherein each of the stages has one or more decision makers which are cascaded to propagate the earliest detection signal pulse of one of a respective detector unit as a timing signal; - a time-to-digital converter configured to receive the timing signal and to provide a time stamp depending on the timing signal wherein the time stamp indicates the distance information for a pixel of the image

Oscillator arrangement for time-to-digital converter for large array of time-of-flight image sensor devices

An oscillator arrangement for time-to-digital converters for a 3D image sensor device includes a plurality of oscillators arranged as an array each oscillator being associated to one time-to-digital converter, and at least one coupling unit respectively arranged between at least two of the oscillators, so that oscillation in the at least two oscillators at a fundamental frequency is synchronized between the at least two coupled oscillators