The first step in designing a 3D LiDAR (light detection and ranging) sensor is to pick a laser source for generating photons to illuminate the scene. Each LiDAR has a receiver which collects and processes the light reflected back from the targets to provide real-time 3D depth information without ambiguity.
The laser is a critical piece of the puzzle for any LiDAR sensor’s architecture and most manufacturers today are using legacy components. Sense comes out with a new digital light source, the Sense Illuminator which features low costs and uniform illumination without scanning either mechanically or electronically.
In existing LiDAR solutions, companies source off-the-shelf laser components which shine IR light at a tiny spot, much like a laser pointer you might use to play with a cat. Their products use multiple lasers to illuminate a ‘column’ or ‘row’ of spots and then mechanically scan the scene to cover the full desired field-of-view (FOV). Since they don’t capture full-frame data, these companies have to keep track of the timestamp for each pixel that is returned per frame. Then, they use that information to correct for motion blur if a target, such as a high-speed vehicle, has moved within that frame.
But why do these companies scan their laser to begin with? The answer is in the laser source; their innate need to scan only exists because their laser can only illuminate that tiny spot rather than the desired FOV so they have to move the laser spot across the FOV for full coverage. This causes inherent trade-offs between range, resolution, frame rate, and FOV.
It also increases system complexity, adds expensive optical components, and introduces tedious calibration and alignment procedures during assembly. As a result, it burdens customers with high-cost sensors with many potential points of failure that struggle with reliability and durability in real world use cases.
Most end customers that actually use these mechanical sensors in automotive or industrial markets are well-versed with these failures—especially in spinning LiDARs where the internal bearings can fail frequently and the sensors have to be refurbished or replaced. In addition, mechanical sensors—whether spinning, MEMS-based, or utilizing galvanometers—have trouble maintaining depth accuracy during high amplitude vibration pulses, such as those experienced on the road throughout the life of a vehicle.
For details, click Photons…Flood the Scene – Sense Photonics
Hordon Kim
International Editor, hordon@powerelectronics.co.kr
