Automotive Electronics

Distance Sensors - Optical

Basic Description

LIDAR (for Light Detection and Ranging) sensors work by transmitting a pulse of light (usually red or infrared) and waiting for the reflected signal. The delay associated with reception of the reflected signal can be correlated to the distance of the reflecting object. LIDAR sensors are used on autonomous driving vehicles. They can detect objects with much greater resolution than radar or acoustic sensors due to the small wavelengths employed. However, the optical signals are more easily scattered by small particles in the air such as rain, smoke or dense fog. Since LIDAR signals are very directional, coverage of a wide area generally requires the beam to be scanned using mechanical movement. Because of this, LIDAR is generally more expensive than other types of distance sensors.

Another type of optical distance sensor is the proximity sensor. These sensors utilize an LED or laser as an emitter and a photodiode as a receiver. The emitter's beam is directed onto the surface it is detecting where it diffusely reflects. Some of the reflected beam will be directed towards the photodiode if the object is within the measurement range.

Acuity, Avago, Balluff, Continental, Denso, Dimetix, Keyence, Leuze, Moduloc, Omron, NFM, Velodyne, Vishay
For More Information
[1] Distance sensors (range finders) comparison, Jean-Christophe Zufferey, Oct. 9, 2007.
[2] Fundamentals of Photoelectric Sensors, Gary Frigyes et al.,
[3] Laser Rangefinder, Wikipedia.
[4] Photodiode, Wikipedia.
[5] Volvo City Safety - Laser Radar Auto Brake Safety System, YouTube, June 2, 2011.
[6] Velodyne Lidar Vision Sensor System for the Google Self-Driving Car, YouTube, Jan 21, 2013.
[7] LIDAR, Lasers and Logic: Anatomy of an Autonomous Vehicle, Amir Iliaifar, Digital Trends, Feb. 6, 2013.