Multi-echo

When a laser hits a transparent object such as glass, rain, or fog, or a translucent object, two types of lasers will be returned to the sensor. One is a laser that reflects off the transparent object and another is a laser which transmits through the transparent object and reflects off an object in the back.
The multi-echo is a function which acquires the distance data returning two or more laser beams at the same step angle only.

When using a reflective sensor, it is very difficult to use it in an environment with rain or fog because it causes false detection. If you use multi-echo function, you can reduce troubles because it is possible to distinguish between objects with a close distance value such as rain and fog and objects with a long distance that you actually want to detect.