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摘要:
激光雷达可以高精度、高准确度地获取目标的距离、速度等信息或者实现目标成像,在测绘、导航等领域具有重要作用。本文首先介绍了从机械式向全固态过渡的微机械系统激光雷达解决方案;其次针对激光雷达全固态的发展需求,介绍了面阵闪光、相控阵激光雷达的基本原理和典型实现方法,从液晶、光波导材料等研究方向阐述相控阵激光雷达研究现状;最后总结了目前激光雷达存在的问题及不同的解决方案,并对未来发展趋势进行了展望。
Abstract:Light detection and ranging (LiDAR) system can be used to capture the distances and speeds of the targets with high resolution and high accuracy, and can also form imaging. It is important for the applications such as mapping, and navigation, et al. This paper introduces the LiDAR solution based on micro-electromechanical system (MEMS) is a transitional scheme from mechanical one to solid-state. Meanwhile, in terms of the requirement of solid-state, the principles of Flash and optical phased array LiDAR are introduced in this paper. At the same time, the miniaturization trend of LiDAR is presented with optical phased array based on liquid crystal (LC) and integrated optical waveguides. At last, the performances and open issues of the solutions for LiDAR are concluded and the development trends of LiDAR are summarized with outlook.
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Key words:
- LiDAR /
- MEMS /
- Flash /
- optical phased array
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Overview: Radar is utilized as the eyes to have the sense of the world for human, which has the ability to detect the target in dead zone and long distance. It plays a significant role in the military and civilian domains. Light detection and ranging (LiDAR) system has the shorter wavelength than that of the traditional radar. Thus, LiDAR systems have higher resolutions of distance, angle, and speed compared with the radar system. Due to the high direction and high coherence of laser, LiDAR systems can realize detection and ranging of the remote targets without external interference. The information of distance and speed can be obtained with coherent detection of LiDAR, which can be used in the fields such as missile guidance, mapping, driverless technology and so on.
LiDAR can be classified as three types: mechanical, mixed solid-state, and solid-state. The mechanical LiDAR systems utilize the mechanically rotating parts to realize beam steering, of which the field of view is large but the assembly is complexed and the scanning speed is low. The solid-state LiDAR systems are without mechanical scanners and can be realized by the micro-electromechanical system (MEMS), Flash and optical phased array (OPA) technologies. MEMS based LiDAR realizes the beam scanning with micro mirror. The MEMS mirrors can be actuated by electrostatic method, electromagnetic method, piezoelectric method, and electrothermal method. The integration of the MEMS system is relatively high but the field of view is limited by the displacement of the micro mirror. Flash based solid-state LiDAR is proposed in 1990s, the techniques of which are relatively mature and have commercial applications. However, the detection range and field of view are limited. OPA emerged in 1970s is a novel optical beam scanning technology, which is based on principles and techniques of the microwave phased array. The OPAs realize beam steering based on the principle of changing the optical phase in the array unit, which will modulate the wavefronts of the emission beam. The OPA beam scanners are non-inertia, precision, accurate and have the potential to be utilized in the LiDAR field. The technique is emerging with liquid crystal (LC) and integrated optical waveguides and so on. The OPAs with high integration can satisfy the requirements of the miniaturization trends in some driverless fields. In the future, the LiDAR will develop on the way to the solid state and miniaturization trend.
In this paper, we review the recent research of OPA LiDAR systems in Section 2, the basic working principle of LiDAR system is introduced. In Section 3, the technique researches of MEMS based LiDAR are introduced. In Section 4, the principle and research of Flash LiDAR are introduced. The LC OPA and integrated waveguide OPAs for LiDAR, including the electro-optic materials, silicon-on-insulator (SOI) platform and so on, are introduced in Section 5. The performances of the techniques are compared and the open issues and outlook are given in the Section 6.
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