Saturday, February 23, 2019

Actlight DPD Article

Laser Focus World publishes Lausanne, Switzerland-based Actlight article "Dynamic photodiodes reach single-photon sensitivity at low voltages, with minimal noise" by Maxim Gureev (Actlight CTO) and Denis Sallin (Director of Engineering). Few quotes:

"ActLight’s dynamic photodiode (DPD) uses a new operating mode that converts light intensity into time.1-3 The applied voltage is not constant, but is switched from reverse to forward bias. Applied forward bias induces a large forward current that doesn’t start immediately, but after a time delay (see Fig. 1). The forward current magnitude is controlled only by the applied voltage, and its value does not depend on the light intensity. In contrast, the delay time (triggering time) is a function of the absorbed light power."

"With CMOS compatibility, a high-amplitude output signal, low noise, and low voltage operation, the DPD can also be tuned to reach single-photon sensitivity. This could dramatically enhance the performance of wearable devices and smartphones."

"ActLight developed an iToF method using its DPD that can be manufactured with a standard CMOS or CMOS Image Sensor (CIS) process. The low-voltage iToF range meter demonstrator allows measurement at distances up to 5 m in a wide range of lighting conditions (see Fig. 3). Furthermore, it has demonstrated full sun (>100 klux) background light immunity."

Array Temperature Effects in Pixel and Sensor Performance

MDPI Special Issue "Advanced CMOS Image Sensors and Emerging Applications" publishes a paper "Compensation for Process and Temperature Dependency in a CMOS Image Sensor" by Shuang Xie and Albert Theuwissen from Delft University of Technology and Harvest Imaging.

"This paper analyzes and compensates for process and temperature dependency among a (Complementary Metal Oxide Semiconductor) CMOS image sensor (CIS) array. Both the analysis and compensation are supported with experimental results on the CIS’s dark current, dark signal non-uniformity (DSNU), and conversion gain (CG). To model and to compensate for process variations, process sensors based on pixel source follower (SF)’s transconductance gm,SF have been proposed to model and to be compared against the measurement results of SF gain ASF. In addition, ASF’s thermal dependency has been analyzed in detail. To provide thermal information required for temperature compensation, six scattered bipolar junction transistor (BJT)-based temperature sensors replace six image pixels inside the array. They are measured to have an untrimmed inaccuracy within ±0.5 ⁰C. Dark signal and CG’s thermal dependencies are compensated using the on-chip temperature sensors by at least 79% and 87%, respectively."

Friday, February 22, 2019

Non-Destructive Photon Sensing

Intechopen 2018 book "Photon Counting - Fundamentals and Applications" has a chapter "Quantum Non-Demolition Measurement of Photons" (QND) by Keyu Xia from Nanjing University, Nanjing, China. The chapter reviews the possible ways to detect photons without absorbing them that can open a number of interesting opportunities in photon sensing:

"QND measurement opens a door for precise measurement and versatile applications in photon-based quantum information processing. In principle, QND measurement enables repeated measurement of photon number, n, of a light beam. Because QND measurement does not disturb the photon number of light, it allows one to measure the photon number many times. This can surpass the standard quantum limit bounded by the “shot-noise” and allows to measure light with ultrahigh sensitivity. QND measurement down to the single photon level further enables potential application in quantum information processing. Remarkably, when a single signal photon can induce a π phase shift to another probe photon, the scheme for QND measurement essentially has the potential to implement a quantum controlled-phase gate between these two photonic modes. This kind of gate is a universal quantum gate for quantum computation. Another important application is to squeeze light via QND measurement. Although QND measurement has been well studied theoretically and has been realized in experiments, it is still questioned in its interpretation [31]. Monroe comments that photons can be independently generated once a signal photon is detected via absorption. He claims that the concept of QND measurement is confusing and should be demolished. However, his comments are also questionable. Squeezing light through QND measurement cannot be realized by simply generating photons according to the detection events. In summary, the concept of QND measurement applied to photons promises of great applications in quantum measurement. The progress approaching the single photon level may provide a simple router for implementing quantum information processing [32] or even quantum telescope [33]."

Royole Flexible Smartphone Omits Dedicated Selfie Camera

PRNewswire: Royole FlexPai foldable smartphone camera set-up is made up of a 20MP telephoto module, and a 16MP wide-angle module, that can be used for both normal photo shooting or taking a selfie, thanks to the dual view camera mode. There is no dedicated selfie camera in the phone:

Sony Hiring More Image Sensor Engineers in Japan, Expanding Polarization Sensors Lineup

Reuters: Sony Corp swill assign 40% of its new engineer hires in Japan over the next two years to the chip business which includes image sensors, as it looks for growth from new applications in everything from cars to phones. Sony plans to hire 320 new engineers annually in Japan this year and the next, up from 250 in 2018. The figures do not include those to be hired by overseas units.

The allocation is in line with the company’s plans to invest 600b yen ($5.4b) in image sensor business over the three years through March 2021, or half of the group’s planned capital expenditures.

The company cut its annual profit outlook for imaging sensors this month to 130b yen, accounting for just 15% of the Sony Corp.’s overall profit, due to weakening global demand for smartphones.

In another news, Sony adds a second polarization sensor to its portfolio - a 12MP, 1.1-inch IMX253MZR/MYR:

Thursday, February 21, 2019

Albert Theuwissen Reviews ISSCC 2019 - Part 3

Albert Theuwissen continues his ISSCC presentations review. The third part covers University of Toronto in cooperation with Synopsys and FBK presentation “Dual-tap pipelined-code-memory coded-exposure pixel CMOS image sensor for multi-exposure single-frame computational imaging” by Navid Sarhangnejad, Nikola Katic, Zhengfan Xia, Mian Wei, Nikita Gusev, Gairik Dutta, Rahul Gulve, Harel Haim, Manuel Moreno Garcia, David Stoppa, Kiriakos N. Kutulakos, and Roman Genov:

Panasonic presentation "A 400x400-Pixel 6μm-Pitch Vertical Avalanche Photodiodes (VAPD) CMOS Image Sensor Based on 150ps-fast Capacitive Relaxation Quenching (RQ) in Geiger Mode for Synthesis of Arbitrary Gain Images" by Yutaka Hirose, Shinzo Koyama, Toru Okino, Akito Inoue, Shigeru Saito, Yugo Nose, Motonori Ishii, Seiji Yamahira, Shigetaka Kasuga, Mitsuyoshi Mori, Tatsuya Kabe, Kentaro Nakanishi, Manabu Usuda, Akihiro Odagawa, and Tsuyoshi Tanaka:

University of Edinburgh, ST, and Heriot-Watt University present “A 246×256 40nm/90nm CMOS 3D-stacked 120dB dynamic range reconfigurable time resolved SPAD imager” by Robert K. Henderson, Nick Johnston, Sam W. Hutchings, Istvan Gyongy, Tarek Al Abbas, Neale Dutton, Max Tyler, Susan Chan, and Jonathan Leach:

Omnivision Announces 1/4-inch 8MP Sensor for Smartphones

PRNewswire: OmniVision announces the OV08B 8MP sensor featuring 1.12um pixel for the broad smartphone camera markets. This new image sensor supports mainstream selfie imaging, as well as multicamera configurations. The new sensor fits in 5.1 x 6.5mm fixed-focus modules for front-facing cameras. Placing pads on the top and bottom of the sensor also reduced its X dimension, enabling narrow-bezel designs and 4:3 aspect ratios. The OV08B offers Bayer imaging and a 4-cell binning capability for better low-light video performance.

"The 1/4 inch 8 MP sensor category continues to see tremendous volume opportunities in the mainstream mobile phone camera market. In addition to selfie cameras, we are also expecting to see these sensors being deployed in multiple-camera configurations, enabling features such as optical telephoto zoom and ultrawide-angle cameras. The multiple-camera configuration is fast becoming a standard requirement in everything from entry-level to high-end smartphones," said James Liu, product marketing manager at OmniVision. "The OV08B provides the best combination of performance, features, cost and power consumption in a 1/4 inch optical format, and is an ideal option for customers upgrading from 5 MP image sensors."

Samples are expected to be available in April 2019.

Light Co. Signs Agreement with Sony

Globenewswire: Light Co. announces the agreement with Sony Semiconductor to jointly work on development and marketing of multi-image sensor solutions. The agreement allows Light to use and recommend to its customers and partners, Sony’s image sensors built in Light’s computational imaging solutions and reference designs. These new reference designs combine Light’s multi-camera technology together with Sony’s image sensors to create new multi-camera applications and solutions beginning with the introduction of smartphones containing four or more cameras.

Sony is the recognized quality and market share leader in image sensors and we are thrilled to partner with them,” said Dave Grannan, CEO and co-founder, Light. “We are entering an entirely new era of intelligent imaging applications that will transform smartphones, autonomous vehicles, and security systems. With Sony’s world-class image sensors, we can introduce new innovations in the multi-camera imaging space.

We are excited to be working with Light and driving multi-sensor-based products and solutions into the market,” said Hank Ochi, president of Component Solutions Business Division, Sony Electronics Inc. “Light and its technology are transforming how devices see the world. This new partnership will allow us to work together to evolve and speed up the design of today’s multi-image sensor enabled connected devices. Starting today, our jointly developed reference designs will help our smartphone OEMs to quickly and easily enhance the imaging capability of multi-camera enabled smartphones.

Wednesday, February 20, 2019

Samsung Galaxy S10 5G Features 6 Cameras

Samsung announces S10 generation of its flagship Galaxy phones, including the top of the range 5G model with ToF rear camera. CNET put together a nice table summarizing the camera differences in the S10 family:

"The Galaxy S10 5G truly packs the power of a professional-grade camera into your phone by offering a total of six lenses – two on the front and four on the back. In addition to featuring all of the lenses included in the Galaxy S10+, the 5G model introduces Samsung’s next-generation 3D Depth Camera.

This innovative camera allows the device to accurately capture depth by measuring the length of time it takes for an infrared light signal to bounce off the photograph’s subject. The camera uses the resulting depth information to improve the quality of portrait-style images, and to power exciting new features like Video Live focus and Quick Measure. The former allows you to apply cinema-quality bokeh effects to recorded videos, while the latter enables you to use your phone to instantly measure distance, area or volume.

Albert Theuwissen Reviews ISSCC 2019 - Part 2

The second part of Albert Theuwissen's review of image sensor session at ISSCC 2019 talks about “A Data Compressive 1.5b/2.75b Log-Gradient QVGA Image Sensor with Multi-Scale Readout for Always-On Object Detection” by Christopher Young, Alex Omid-Zohoor, Pedram Lajevardi, and Boris Murmann from Stanford University and Robert Bosch:

“A 76mW 500fps VGA CMOS Image Sensor with Time-Stretched Single-Slope ADCs Achieving 1.95 e– Random Noise” by Injun Park, Chanmin Park, Jimin Cheon, and Youngcheol Chae form Yonsei University and Kumoh National Institute of Technology, Korea: