Tuesday, November 24, 2020

Draper Si-Ge-based Single-Photon Detector Gets Award

Draper reports that its Single Photon Detector (SPD) patent has been awarded by by the Boston Patent Law Association at its 10th Annual Invented Here! event.

Draper’s SPD is intended to be configured in an array of multiple SPDs capable of detecting a single photon with high timing resolution, speed and efficiency over an unparalleled wavelength range, from visible to infrared.

Draper’s SPD uses a silicon-germanium photodiode, which enables detection of the longer wavelengths of light and performance similar to a conventional silicon SPD. It can also function at room temperature. The performance of the new detector is intended to enable ultralow dark-counting rate and timing resolution of better than one nanosecond.

Steven Spector, principal member of Draper’s technical staff, developed the technology with a team at Draper. He said, “Draper’s SPD is so fast and efficient that it can absorb and detect a single particle of light and reset itself for the next one within a nanosecond.

The patent US10636918 "Single electron transistor triggered by photovoltaic diode" presents the idea using a single electron bipolar avalanche transistor (SEBAT) circuit:

"Embodiments of the present invention are directed to a single photon detection circuit that includes a germanium photodiode configured with zero voltage bias to avoid dark current output when no photon input is present and also configured to respond to a single photon input by generating a photovoltaic output voltage and current. A single electron bipolar avalanche transistor (SEBAT) has a base emitter junction connected in parallel with the germanium photodiode and is configured so that the photovoltaic output voltage triggers an avalanche collector current output.

The SEBAT may be formed of silicon material. The germanium photodiode may be formed using germanium material used as deposited plus any dopings and anneals needed to turn it into a photodiode.

Unlike SPADs, which are triggered by single photons, SEBATs are triggered by single electrons. For single electron detection operation, the collector voltage Vcc is set to a high voltage above the breakdown of the collector-base junction. If a negative voltage is applied to the emitter E, the base-emitter junction is forward biased and an emitter current IE appears."

ON Semi Presents its SPAD Products for LiDARs

ON Semi publishes a video on its SPAD products for laser rangefinders and LiDARs:

Curved Organic Heterojunction Neuromorphic Image Sensor

 Nature paper "Curved neuromorphic image sensor array using a MoS2-organic heterostructure inspired by the human visual recognition system" by Changsoon Choi, Juyoung Leem, Min Sung Kim, Amir Taqieddin, Chullhee Cho, Kyoung Won Cho, Gil Ju Lee, Hyojin Seung, Hyung Jong Bae, Young Min Song, Taeghwan Hyeon, Narayana R. Aluru, SungWoo Nam, & Dae-Hyeong Kim (Seoul Institute for Basic Science (IBS), Seoul National University, Gwangju Institute of Science and Technology, and University of Illinois at Urbana-Champaign) sets off a lot of Google News Alerts for me: neuromorphic, organic, curved, heterojunction.

"Conventional imaging and recognition systems require an extensive amount of data storage, pre-processing, and chip-to-chip communications as well as aberration-proof light focusing with multiple lenses for recognizing an object from massive optical inputs. This is because separate chips (i.e., flat image sensor array, memory device, and CPU) in conjunction with complicated optics should capture, store, and process massive image information independently. In contrast, human vision employs a highly efficient imaging and recognition process. Here, inspired by the human visual recognition system, we present a novel imaging device for efficient image acquisition and data pre-processing by conferring the neuromorphic data processing function on a curved image sensor array. The curved neuromorphic image sensor array is based on a heterostructure of MoS2 and poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane). The curved neuromorphic image sensor array features photon-triggered synaptic plasticity owing to its quasi-linear time-dependent photocurrent generation and prolonged photocurrent decay, originated from charge trapping in the MoS2-organic vertical stack. The curved neuromorphic image sensor array integrated with a plano-convex lens derives a pre-processed image from a set of noisy optical inputs without redundant data storage, processing, and communications as well as without complex optics. The proposed imaging device can substantially improve efficiency of the image acquisition and recognition process, a step forward to the next generation machine vision."

Sony Promotional Videos: SWIR, Polarization, ToF

Sony publishes 4 promotional videos about its image sensors: SWIR, polarization sensing, and ToF:

Monday, November 23, 2020

LiDAR News: Luminar, Mobileye, Voyant, Tesla, Broadcom, Sense Photonics

BusinessWire, Forbes: Luminar has struck a deal with Mobileye, an Intel company, to supply Luminar lidar for the company’s Autonomous Vehicle (AV) Series solution in its next phase of driverless car development and testing.

As part of the agreement, Mobileye will collaborate with Luminar to use its lidar for the first generation of its level 4 Mobility-as-a-Service (MaaS) pilot and driverless fleet in key markets around the world, including Tel Aviv, Israel; Dubai, UAE; Paris, France; and Daegu City, South Korea.

Financial terms of the deal aren’t being disclosed. They don’t include Mobileye taking an equity stake in Luminar.

The camera gets you the first 99%” of visual data for self-driving vehicles, says Austin Russell, Luminar CEO. “Lidar gets you that last 1%.” 

Voyant Photonics responds to Elon Mask statement "you need to focus on vision because the entire road system is based on passive optical.

So you have to sell passive optical to have a self-driving system that is generally a solution. And once you solve passive optical, you’ve solved self-driving. So, why bother with anything else?"

Voyant says "nobody drove to work with any electromagnetic radiation coming out their eyes. That is not what eyes do. Yet, anyone who drove in a Tesla was shooting 77 GHz radio waves out of their front bumper.

Teslas have 77 GHz radars from Continental pumping data into their Autopilot systems."

Broadcom presents its LiDAR approach at today's EPIC Online Technology Meeting on 3D Sensing:

Sense Photonics presents its flash LiDAR solution at today's EPIC Meeting:

Spying with Vacuum Cleaner LiDAR

National University of Singapore presents a paper "Spying with your robot vacuum cleaner: eavesdropping via lidar sensors" by Sriram Sami, Yimin Dai, Sean Rui Xiang Tan, Nirupam Roy, and Jun Han.

"This paper presents LidarPhone, a novel acoustic side-channel attack through the lidar sensors equipped in popular commodity robot vacuum cleaners. The core idea is to repurpose the lidar to a laser-based microphone that can sense sounds from subtle vibrations induced on nearby objects. LidarPhone carefully processes and extracts traces of sound signals from inherently noisy laser reflections to capture privacy sensitive information (such as speech emitted by a victim's computer speaker as the victim is engaged in a teleconferencing meeting; or known music clips from television shows emitted by a victim's TV set, potentially leaking the victim's political orientation or viewing preferences). We implement LidarPhone on a Xiaomi Roborock vacuum cleaning robot and evaluate the feasibility of the attack through comprehensive real-world experiments. We use the prototype to collect both spoken digits and music played by a computer speaker and a TV soundbar, of more than 30k utterances totaling over 19 hours of recorded audio. LidarPhone achieves approximately 91% and 90% average accuracies of digit and music classifications, respectively."

Sunday, November 22, 2020

SystemPlus Discovers Samsung ToF Sensor in Meizu Phone

 SystemPlus publishes a reverse engineering report "3D Time-of-Flight Module in Meizu 17 Pro."

"The 3D sensing module is packaged in one metal enclosure and includes a new Back-side Illumination (BSI) NIR CMOS Image Sensor (CIS) from Samsung. The sensor features 7 µm pixels and a resolution of 0.3 Mpixels. The ToF uses a vertical cavity surface emitting laser (VCSEL) coming from Lumentum.

A wafer level chip scale packaging (WLCSP) driver integrated circuit from PhotonIC generates the pulse and drives the VCSEL’s power and beam shape."

Saturday, November 21, 2020

Friday, November 20, 2020

Smartsens Enters Smartphone Market with 2MP-13MP Sensor Lineup

BusinessWire: Starting from security and surveillance sensors, Smartsens has recently expanded into automotive applications. Now, the company announces plans to penetrate smartphone image sensor market with the CS (Cellphone Sensor) Series products—including the SC200CS-mono, SC200CS-color, SC500CS, SC800CS, and SC1300CS/SC1301CS—covering a range of 2MP to 13MP resolutions to meet a diverse set of applications and customers.

SmartSens is leveraging its proprietary SFCPixel Technology and ultra-low noise reading circuit design in its new smartphone sensors, borrowing from its years of experience in developing superior night vision imaging technology for security devices. These technologies effectively improve performance in low-light environments, allowing smartphone cameras to capture rich and vibrant images under extremely challenging conditions.

The new CS series deliver excellent signal-to-noise ratio. For example, the SC500CS reduces reading noise by over 30% compared with products of the same specifications in the industry while the fixed noise of SC800CS is significantly reduced by 72% with the Max SNR increased by 3dB compared to similar products. Coupled with the signal-to-noise ratio, the noise reduction optimizes for a natural look and feel.

The other standout features of the CS series include the high dynamic range that enables better images in complex light and shadow environments. Compared with the current 60-70dB dynamic range of mainstream smartphone image sensors, the new CS series products can reach over 72dB with a total range more than 6K electrons and the random noise of less than 1.5 electrons. These capabilities allow associated cameras to process images taken in a wide range of lighting conditions, clearly distinguishing the light and dark details.

The sensors also crucially address the emergence of 5G mobile phones and their associated higher power consumption. This is where the CS series excels. The new range benefits from SmartSens’ unique high-end processing and ultra-low power consumption circuit design that reduces sensor power consumption and extends mobile phone standby time without sacrificing the performance.

Our new range of CMOS image sensors takes SmartSens’ expertise and innovation in mission critical camera applications and brings them to one of the most important devices in consumers’ digital lifestyles: the smartphone,” said Yaowu Mo, SmartSens CTO. “The new CS Series image sensors utilize stable technologies from our other lines—including night-vision imaging, excellent noise reduction, PDAF and ultra-low power consumption—to empower advanced smartphone imaging applications and give users an overall better photography experience.

The SC200CS-mono, SC200CS-color, and SC500CS products are now in production. Samples are available for the SC800CS, SC1300CS and SC1301CS.

Sony Re-Org

Sony Semiconductor Solutions announces a re-organization:

  • The platform technology division and the system development organization of each business division will be reorganized and reorganized into the Imaging & Sensing Edge Core Technology Division.
  • A sensor product design department will be newly established by consolidating some of the product design functions of the Imaging Systems Division, Mobile & Sensing Systems Division, and Sony LSI Design Inc.

DC Reduction Using Hydrocarbon-Molecular-Ion-Implanted Double Epitaxial Si Wafers

 MDPI paper "Reduction of Dark Current in CMOS Image Sensor Pixels Using Hydrocarbon-Molecular-Ion-Implanted Double Epitaxial Si Wafers" by Ayumi Onaka-Masada, Takeshi Kadono, Ryosuke Okuyama, Ryo Hirose, Koji Kobayashi, Akihiro Suzuki, Yoshihiro Koga, and Kazunari Kurita from SUMCO, Japan, promises 40% DC improvement, but needs dual layer epi wafers:

"The impact of hydrocarbon-molecular (C3H6)-ion implantation in an epitaxial layer, which has low oxygen concentration, on the dark characteristics of complementary metal-oxide-semiconductor (CMOS) image sensor pixels was investigated by dark current spectroscopy. It was demonstrated that white spot defects of CMOS image sensor pixels when using a double epitaxial silicon wafer with C3H6-ion implanted in the first epitaxial layer were 40% lower than that when using an epitaxial silicon wafer with C3H6-ion implanted in the Czochralski-grown silicon substrate. This considerable reduction in white spot defects on the C3H6-ion-implanted double epitaxial silicon wafer may be due to the high gettering capability for metallic contamination during the device fabrication process and the suppression effects of oxygen diffusion into the device active layer. In addition, the defects with low internal oxygen concentration were observed in the C3H6-ion-implanted region of the double epitaxial silicon wafer after the device fabrication process. We found that the formation of defects with low internal oxygen concentration is a phenomenon specific to the C3H6-ion-implanted double epitaxial wafer. This finding suggests that the oxygen concentration in the defects being low is a factor in the high gettering capability for metallic impurities, and those defects are considered to directly contribute to the reduction in white spot defects in CMOS image sensor pixels."

Thursday, November 19, 2020

Yole Webinar on Smartphone Camera Trends

 Yole Developpement webcast "Smartphone Camera Trends" consists of 3 parts:

  1. Yole Développement's Market and Technology brief, reviewing current trends for smartphone cameras.
  2. Beneq presents Atomic Layer Deposition as a uniquely qualified solution to meet advances in wafer level optics, advanced 3D integration, and the perennial need for improved sensor responsivity.
  3. System Plus Consulting presents a reverse costing brief, with the latest evolution of cameras in flagship smartphones and the main players’ technical choices.

Canon Licenses Xperi DBI Hybrid Bonding IP to Use in Stacked CMOS Sensors

BusinessWire: Xperi Holding announces Canon’s license of Invensas DBI hybrid bonding IP portfolio to enhance its image sensors.

Canon is recognized by customers around the world as a long-standing leader in optical and imaging products,” said Craig Mitchell, President of Invensas, a wholly owned subsidiary of Xperi. “We are proud to support Canon’s innovation efforts in the field of image sensors and look forward to expanding our relationship in the future.

Wednesday, November 18, 2020

Assorted News: Omnivision, Sony, ASE, MISIS, Caeleste

Yuanchuang: Omnivision reports that testing, packaging, and known good wafer reconstruction expenses constitute 9.74% of its image sensor cost.

Digitimes: Sony has added ASE to its backend for automotive CIS supply chain. ASE will set up a new business unit to handle Sony's CIS orders. ASE reportedly has become Sony's second backend partner for processing automotive image sensors, marking its return to the CIS packaging segment following years of hiatus.

PRNewswire: Russian scientists from NUST MISIS National Technological Initiative Center "Quantum Communications" are developing what they call the world's first prototype of an infrared single-photon video detector.

"The detector itself is located inside the cryostat at a temperature of only 2 K, which is close to absolute zero. When a photon is detected, it sends a signal to the processing circuit, and an image appears on the display", comments Grigory Goltsman, Chief Researcher at NUST MISIS NTI Center "Quantum Communications", founder of "Skontel" company.

Caeleste: Bart Dierickx (Co-Founder and CTO) and Ajit Kalgi (Senior Analog Designer) invented a method to increase the charge collection, thus image lag, of a very long narrow photodiode. The N-type pinned photodiode (PPD) itself is constant in width and homogenous in concentration. It is squeezed between two P+ regions, that are at variable distance from the photodiode (Figure 1).

The presence of the P+ region affects the potential in the photodiode, and the construction is so that the potential drops evenly and monotonically, so as to have an effective electric filed in the photodiode that collects the charges (Figure 2).

Tuesday, November 17, 2020

Holy Grail Claim: Perfect RGB‐IR Color Routers Instead of Color Filters

Wiley Journal of Advanced Photonics Research publishes a paper "Perfect RGB‐IR Color Routers for Sub‐Wavelength Size CMOS Image Sensor Pixels" by Nathan Zhao, Peter B. Catrysse, and Shanhui Fan from Stanford University.

"A critical capability of all image sensors is to separate light into its individual color components. In most technologies today, this is done via color filters. Filters, however, intrinsically waste a large fraction of the light by absorption or scattering. This affects image sensor performance since the amount of light incident on each image sensor pixels reduces quadratically with linear scaling of pixel size. This is particularly detrimental to the performance of (sub‐)wavelength size pixels. In this paper, we provide a conceptually novel approach for color functionality in image sensors, by designing a color router that achieves perfect RGB‐IR color routing for sub‐wavelength size pixels. In a color router, all incident light for each color channel is routed directly and without loss to the photodetector of the corresponding color channel pixel. We show that color routers can be designed to near‐perfectly match a prescribed spectral shape, which is important for color image processing. We further show that we can design these routers to achieve specific spectral bandwidth and to meet angular as well as fabrication constraints. This article is protected by copyright."

Airy3D Explains its Technology

LaserFocusWorld publishes an article "Diffraction mask design brings 3D imaging to standard CMOS image sensors" by Gil Summy (Director, Optics Group) and James Mihaychuk (Product Manager) from AIRY3D, Montreal, QC, Canada.

Airy3D's "DEPTHIQ technology places an optical encoding transmissive diffraction mask (TDM) on a standard CMOS image sensor to generate both high-quality 2D color images and near-field depth maps that are inherently correlated.

The addition of two thin layers of transmissive material, collectively making the TDM, over the top of most CMOS image sensors can provide 3D sensing capabilities with virtually no reduction in 2D image quality. These layers use the process of diffraction from a phase grating to realize compact, low-cost, low-compute solutions for 3D image capture.

The physics underlying the TDM is diffraction from a phase grating. Thus, the TDM is a transparent structure rather than a lossy mask and does not rely on opaque, lithographically patterned features. As such, a TDM can be added to any existing image-sensor design through a small number of postprocessing steps.

Because it is typically only a few microns thick, a TDM can normally be added to an image sensor without requiring changes to the lens or other camera-module components. However, as with any image sensor, it remains important to select a compatible lens in terms of numerical aperture (NA), chief-ray angle (CRA), and alignment tolerancing.

To date, these TDM design approaches have been successfully applied to implement single-sensor 3D imaging solutions based on a wide range of CMOS image sensors. The TDM approach has been adapted to both backside-illuminated mobile sensors for smartphones and frontside-illuminated, global-shutter machine-vision sensors. As such, TDM structures have been incorporated onto sensors having pixel pitches from about 1 to 3 µm and pixel counts from about 2 to 20 Mpixels."

Monday, November 16, 2020

SWIR Sensor for Driver Monitoring

 Trieye publishes an article "SWIR Keeping a Closer Eye on Driver Monitoring Systems."

"DMS do not function properly under a wide range of scenarios, such as when the sun is shining into a car and the ambient light blinds the camera or when a street is covered with trees or buildings and creates shadow patterns that confuse the DMS algorithms. Another example is when reflections on glasses from different objects and vehicle headlights make it difficult for the gaze detection algorithms to differentiate between pupils and other reflections.

SWIR can be leveraged to solve the low visibility challenge for the car interior with full robustness to ambient illumination. It delivers enhanced vision even under the most challenging scenarios, with significant efficacy at night, when most needed. This function is enabled by operation in the solar-blind region, which prevents glare and shade patterns, combined with the eye-safe powerful illumination (SWIR can be used with 3-5 orders of magnitude more power and still be eye-safe, even in pulsed mode). This allows for an increased Signal-to-Noise Ratio (SNR) and therefore more precise and reliable real-time monitoring."