LiDAR is regarded as a key sensing technology across industries, playing an essential role in robotics, autonomous driving, and smart cities. In recent years, solid-state LiDAR has been viewed as a promising technology and has become a hot topic in the industry.
What is Solid-State LiDAR?
In theory, solid-state LiDAR contains no moving parts. Two typical technical routes—Optical Phased Array (OPA) and Flash LiDAR—are considered true solid-state LiDAR solutions.
However, in recent years, certain LiDARs with small non-rotating moving components have also been classified as “solid-state.” These devices share many of the performance traits of solid-state LiDAR—such as higher resolution and a limited horizontal FOV (forward-facing rather than 360°)—but strictly speaking, they cannot be considered pure solid-state LiDAR.
How Solid-State LiDAR Works
Solid-state LiDAR detects targets primarily by analyzing reflected or received light waves. Much of its design is derived from research into 3D image sensors and infrared focal plane imaging. In a focal plane detector, an array of photosensitive elements is arranged across the focal plane. Infrared light from infinity is focused onto these elements through an optical system. The detector converts the received light signals into electrical signals, amplifies and samples them, and outputs them via buffering and multiplexing systems to form images in the monitoring system.
Three Main Technical Routes of Solid-State LiDAR
After years of development, three main approaches have emerged:
1.MEMS (Micro-Electro-Mechanical Systems)
MEMS technology miniaturizes and integrates mechanical components into silicon chips through microelectronic processes, enabling large-scale production. In LiDAR, MEMS micromirrors perform vertical scanning, while horizontal scanning is achieved by rotating the entire system. The light source often uses fiber lasers, as 905nm laser diodes struggle with high repetition rates that could shorten their lifespan.
Strictly speaking, MEMS is not fully solid-state since mechanical elements remain, albeit miniaturized.
2.OPA (Optical Phased Array)
OPA presents an ideal chip-level LiDAR solution. It uses an array of light sources, controlling the phase differences of emissions to form a directed main beam. By steering the beam electronically, scanning across multiple directions is achieved.
OPA offers millimeter-level accuracy and supports miniaturization, solid-state reliability, and cost reduction. However, challenges remain in increasing point cloud density and overcoming high production costs.
3.Flash LiDAR
Flash LiDAR does not scan like MEMS or OPA. Instead, it emits a wide laser pulse that illuminates the entire field of view at once. A highly sensitive receiver then captures the reflected signals to reconstruct the surrounding environment.
Advantages of Solid-State LiDAR
Solid-state LiDAR, particularly those using OPA, provides several notable advantages:
1.Simple structure, compact size – No rotating parts, leading to smaller form factor, longer lifespan, and reduced costs.
2.High scanning precision – Scanning accuracy depends on electronic signal control, reaching up to 0.001° precision.
3.Excellent controllability – Allows selective high-density scanning in targeted areas.
4.High scanning speed – Scanning speed depends on material electronic properties, often reaching MHz levels.
Disadvantages of Solid-State LiDAR
However, solid-state LiDAR also faces challenges:
1.Limited field of view – Cannot achieve full 360° scanning; multiple sensors (at least front and rear) are required for complete coverage.
2.Sidelobe issues – Optical diffraction causes secondary beams outside the main lobe, dispersing energy.
3.High manufacturing difficulty – OPA requires unit sizes ≤ half the wavelength (≈500 nm for 1 μm lasers), demanding extremely high fabrication precision.
4.Large receiving area, poor signal-to-noise ratio – Unlike mechanical LiDAR with small receivers, solid-state LiDAR requires a large receiving surface, making it more sensitive to ambient noise and harder to process.
Conclusion
Currently, no commercial solid-state LiDAR product simultaneously meets the expectations of high reliability, low cost, and long-range detection. This reality has delayed mass production schedules for many solid-state LiDAR companies.
Although the industry predicts that solid-state, miniaturized, and low-cost LiDAR will dominate in the future, for now, mechanical LiDAR remains the mainstream technology.
Disclaimer: The views in this article are solely those of the author and do not represent SLAMTEC’s official position.
Principles, Advantages, and Disadvantages of Solid-State LiDAR
