Reviews Online

In a recent preprint ( https://arxiv.org/pdf/2209.11772.pdf ) Gyongy et al. describe a new 64x32 SPAD-based direct time-of-flight sensor with in-pixel histogramming and processing capability. Abstract 3D flash LIDAR is an alternative to the traditional scanning LIDAR systems, promising precise depth imaging in a compact form factor, and free of moving parts, for applications such as self-driving cars, robotics and augmented reality (AR). Typically implemented using single-photon, direct time-of-flight (dToF) receivers in image sensor format, the operation of the devices can be hindered by the large number of photon events needing to be processed and compressed in outdoor scenarios, limiting frame rates and scalability to larger arrays. We here present a 64 × 32 pixel (256 × 128 SPAD) dToF imager that overcomes these limitations by using pixels with embedded histogramming, which lock onto and track the return signal. This reduces the size of output data frames considerably, enabling max

The June 2022 issue of IEEE Trans. Electron. Devices has an invited paper titled Direct Time-of-Flight Single-Photon Imaging by Istvan Gyongy et al. from University of Edinburgh and STMicroelectronics.  This is a comprehensive tutorial-style article on single-photon 3D imaging which includes a description of the image formation model starting from first principles and practical system design considerations such as photon budget and power requirements. Abstract: This article provides a tutorial introduction to the direct Time-of-Flight (dToF) signal chain and typical artifacts introduced due to detector and processing electronic limitations. We outline the memory requirements of embedded histograms related to desired precision and detectability, which are often the limiting factor in the array resolution. A survey of integrated CMOS dToF arrays is provided highlighting future prospects to further scaling through process optimization or smart embedded processing. Full paper:  https://doi

C. Bamji et al. from Microsoft published a paper titled "A Review of Indirect Time-of-Flight Technologies" in IEEE Trans. Electron Devices (June 2022). Abstract: Indirect time-of-flight (iToF) cameras operate by illuminating a scene with modulated light and inferring depth at each pixel by combining the back-reflected light with different gating signals. This article focuses on amplitude-modulated continuous-wave (AMCW) time-of-flight (ToF), which, because of its robustness and stability properties, is the most common form of iToF. The figures of merit that drive iToF performance are explained and plotted, and system parameters that drive a camera’s final performance are summarized. Different iToF pixel and chip architectures are compared and the basic phasor methods for extracting depth from the pixel output values are explained. The evolution of pixel size is discussed, showing performance improvement over time. Depth pipelines, which play a key role in filtering and enhanc

Analog Devices has released an industrial-grade megapixel ToF module ADTF3175 and a VGA resolution sensor the ADSD3030 that seeks to bring the highest accuracy ToF technology in the most compact VGA footprint. ADTF3175 Features The ADTF3175 is a complete Time-of-Flight (ToF) module for high resolution 3D depth sensing and vision systems. Based on the ADSD3100, a 1 Megapixel CMOS indirect Time-of-Flight (iToF) imager, the ADTF3175 also integrates the lens and optical bandpass filter for the imager, an infrared illumination source containing optics, laser diode, laser diode driver and photodetector, a flash memory, and power regulators to generate local supply voltages. The module is fully calibrated at multiple range and resolution modes. To complete the depth sensing system, the raw image data from the ADTF3175 is processed externally by the host system processor or depth ISP. The ADTF3175 image data output interfaces electrically to the host system over a 4-lane mobile industry proce

In a blog post titled "Comparing Depth Cameras: iToF Versus Active Stereo" Refael Whyte of Chronoptics compares depth reconstructions from their indirect time-of-flight (iToF) "KEA" camera with active stereo using an Intel RealSense D435 sensor. Specs Setup used for comparisons Bin picking Pallet picking Depth data can also be overlaid on RGB to get colored point cloud visualizations. KEA provides much cleaner-looking results:   KEA D435 They show some limitations too. In this scene the floor has very low reflectivity in IR so the KEA camera struggles to collect enough photons there:   [PS: I wish all companies showed "failure cases" as part of their promotional materials!] Full article here: https://medium.com/chronoptics-time-of-flight/comparing-depth-cameras-itof-versus-active-stereo-e163811f3ac8

ams OSRAM VCSEL illuminator brings benefits of integrated eye safety to Melexis automotive in-cabin monitoring solution Premstaetten, Austria (11 May, 2022) – ams OSRAM (SIX: AMS), a global leader in optical solutions, announces that it is supplying a high-performance infrared laser flood illuminator for the latest automotive indirect Time-of-Flight (iToF) demonstrator from Melexis. The ams OSRAM vertical-cavity surface-emitting laser (VCSEL) flood illuminator from the TARA2000-AUT family has been chosen for the new, improved version of the EVK75027 iToF sensing kit because it features an integrated eye safety interlock. This provides for a more compact, more reliable and faster system implementation than other VCSEL flood illuminators that require an external photodiode and processing circuitry. The Melexis evaluation kit demonstrates the combined capabilities of the new ams OSRAM 940nm VCSEL flood illuminator in combination with an interface board and a processor board and the MLX750