From my understanding of distance sensors, most of them typically rely on an emitted beam being reflected back to the sensor, which would work if the surface is perpendicular to the beam. However, if the target surface is at an angle, I imagine that emitted beams would simply reflect away from the sensor, and the sensor would not be able to measure any distance. I was wondering if some types of distance sensors are able to overcome this, and what makes them work for angled surfaces.
(For example, I see LiDAR being used to measure distances to many differently oriented surfaces, like entire forests, but I’m not sure how the emitted lasers are being reflected back and detected).
Thanks!
In: Physics
An angled surface still diffracts the light that is bouncing off of it, meaning it spreads in *all* directions, not just a perfect angle-in-angle-out bounce. This means that some of it is going to get back to the sensor.
Very rarely will you actually have a LiDAR sensor work on something that is perfectly perpendicular.
Additionally, if you’re bouncing off of something like a mirror, which will have perfect angle-in-angle-out bouncing of the light, there are some strategies that LiDAR systems can use to detect that they’re bouncing off a mirror, which includes using multiple distinguishable measurements that are calibrated at slightly different angles to detect the flip of the mirror.
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