An auto lidar design will start with a corner case such as a small child stepping out from between parked cars at a range. The size, and range, of the object to be detected determine required angular resolution. The range depends on the speed of the auto, which determines stopping distance. An auto lidar should be designed to have a range longer than the required stopping distance by some distance margin. A lidar designer concerned about urban driving will not require as long a range as a designer concerned about the autobahn. Some auto lidars will scan in elevation, but others will use an array of detectors to cover the full elevation, and just scan in azimuth. A long range lidar is more likely to only cover a frontal azimuth region, such as 120 degrees, whereas a shorter range lidar is likely to cover 360 degrees in elevation. It is more likely longer range lidars will be at eye safer wavelengths, such as 1550 nm. To keep cost down many designers prefer diode lasers instead of fibers, but diode lasers cannot be Q switched, so have low peak power. Most auto lidars today are pulsed, so if the designer uses diode lasers there will usually be one laser per detector, whereas with a fiber laser there may only be a single laser illuminating a line that is viewed by a detector array.
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