This paper describes the overview of the special issue on the development of 3D image measurement devices and their application technology. This special issue covers the light receiving elements, scanning devices, and software used in 3D image measurement, as well as the applications that 3D measurement can realize.

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High-speed 3D sensing technologies such as 1000 fps structured light methods are rising. The sensing speed is significant not only for accurate measurement of moving targets but also for real-time feedback. In particular, high-speed devices and high-speed image processing algorithms are required for feedback control of moving targets. This review explains the basic strategy of a triangulation method and introduces high-speed vision devices and state-of-the-art 3D sensing methods based on structured light. High-speed 3D sensing will be one of the critical technologies for real-time response in various fields, including robotics, mobility, security, interface, and augmented reality.

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We propose and develop a new type of non-mechanical three-dimensional (3D) light detection and ranging (LiDAR) system, which integrates a beam-scanning-type laser source and a flash-type laser source. Employing on-chip dually modulated photonic crystal lasers (DM-PCSELs) for both flash and beam-scanning sources, we develop a LiDAR system that is small enough to fit in the palm of the hand. This system is capable of measuring poorly reflective objects in the field of view (FoV) by selectively illuminating these objects with sufficient power by the beam-scanning laser, thereby overcoming the intrinsic issue affecting conventional flash-type 3D LiDAR systems. In addition, we develop and implement a program to have the LiDAR system automatically recognize poorly reflective objects in the FoV and measure their distances by selective illumination. Furthermore, we perform long- distance ranging by using the LiDAR system, including poorly reflective object in the FoV.

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To ensure the reliability of AI systems, it is crucial to consider the reliability of the sensors they use. In this paper, we will focus on the reliability of LiDAR, a key 3D sensor used in autonomous driving and robotics. We will address two key aspects: the importance of high-resolution LiDAR for autonomous vehicles, and the potential for LiDAR to be compromised through “spoofing” attacks. First, we will explore the importance of high-resolution LiDAR for autonomous vehicles, and how it allows cars to fully utilize surrounding 3D information. We will also discuss recent developments in “next-generation” LiDARs from a circuit system perspective. Next, we will turn to the issue of LiDAR security, specifically the threat of spoofing attacks. We will introduce research on this topic and discuss methods for defending against such attacks. By examining these two key aspects of LiDAR reliability, we aim to shed light on the challenges and solutions for achieving trustworthy AI.

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This paper summaries recent indirect time-of-Flight (TOF) range imagers especially for high near-infrared sensitivity and high-range precision.

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Photon counting-based image sensors have attracted attention for a broad range of scientific and industrial applications. In particular, SPAD-based image sensors have a different operating principle from conventional CCD and CMOS image sensors, and have a potential to break the limit of existing imaging and sensing systems. In this paper, we present 1 Megapixel SPAD image sensor for time-resolved applications, and 3.2 Megapixel 3D-stacked backside-illuminated charge focusing SPAD image sensor for low-light imaging applications.

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A terahertz wave is one promising candidate as a carrier for future 6th generation wireless communication (6G). Among several modulation methods of terahertz waves, pulse amplitude modulation (PAM) is expected to be installed in cost effective 6G systems. The PAM system needs a terahertz pulse wave, and a conventional terahertz pulse-wave generation system requires an optical comb generator and a synchronized optical modulator, increasing the system’s complexity and power consumption. In this research, we devised a system for generating and modulating terahertz pulse waves using a fast wavelength- tunable laser and demonstrated it by generating 300-GHz-band terahertz pulses with an arbitrary pulse width.

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