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Pololu Digital Distance Sensor (new LiDAR version) - How do they work?

I have recently purchased a whole bunch of the 4050 Pololu Digital Distance Sensors as they seem to be the holy grail of object sensor that I have been looking for! I built some interactive games that detect balls being thrown through holes in a backboard and always had trouble finding a reliable sensor to detect the object.

Quick History:
I started with a 2-part “beam-break” sensor but the wiring was messy with the emitter on one side and the detector on the other.

Then I switched to a reflective IR sensor (same basic tech, but the emitter and detector are next to each other) but the cheap non-modulated sensors I was using were completely useless outdoors (Sunlight) or in certain indoor lighting situations (Fluorescents, etc).

Then I found the sharp sensors / carriers from Pololu which seemed great at first (Fixed the ambient IR problem as they were modulated) but I would get random “detections” when I had multiple sensors going at the same time - first they seemed “electrical” I was advised to add a parallel capacitor to the power lines for each sensor - it helped but I was still getting false triggers. (I think it was having many sensors in an enclosed space which was causing random triggers - I was never fully sure.)

But alas, the Pololu Digital Distance Sensor (using the 5cm version, #4050) seems to be working exactly as I need it to! Eureka and thank you!

My question is, how do these work?
What I mean is, how are these “LiDAR-based” sensors different than the standard “IR-based” sensors (such as the Sharp sensors). It is my understanding that these also emit some king of modulated IR light and detect it just the same, but they seem to work just fine exposed under direct Sunlight (I tested) and do not seem to be suffering from (that I think were) random IR reflections from inside my enclosure.

My understanding of LiDAR (which isn’t much) is that there is a rotating beam of laser light that is then picked up by a camera or other sensor and the distance of each point of light is measured (time of flight??) to determine how far away objects are. But clearly these sensors are much simpler than the LiDAR we used to see spinning on the top early-prototype self-driving cars, so I am also wondering what makes these “LiDar-based?”

Thanks in advance for the education!


Your understanding of lidar (light detection and ranging) is basically correct except for that the laser does not necessarily need to be rotating like the devices you have seen on self-driving cars (although that is probably the most well known example of lidar technology; rotation allows it to scan around one or more axes instead of looking in just a single direction). It is the fact that these sensors operate by measuring the time for reflected light from the laser to return to the receiver that make our Pololu Digital Distance Sensors lidar based.

This Wikipedia page might be a good place to learn more about lidar in general. If you want to learn more about the sensors on our digital distance sensors, then you could look at the other ST time-of-flight sensor carriers listed in our Lidar/Time-of-Flight Range Finders category page, along with their datasheets and other documentation, since those are less abstracted breakout boards for the same types of sensors as we use on our digital distance sensors. You could also look at ST’s website.

- Patrick