Break Beam sensor inconsistent in sunlight

We are using these adafruit break beam sensors and have noticed the they are very inconsistent in sunlight . Our practice field has big windows that let in a lot of direct Sun at certain times of the day. At 5:00 practice we were getting a lot of direct Sun on the field and the sensors were giving random readings. When driving into shadows or at different times of day they work great .

Has anyone has that issue before ? I know we won’t get direct sun at our regional, but it throws off our practice. Are there sensors available that are less sensitive to sunlight.

IR sensors in general are unreliable around sunlight due to the sun giving off IR waves and there not being a way for a sensor to distinguish between IR waves from the sun and other sources. You could always try shrouding the sensor with something like tape so it only picks up IR waves coming from the emitter

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We absolutely had that issue in 2020. We learned not to practice when the sun was setting, unless it was overcast

In fact the sensors do not work if the robot is outside, learned that one too.

It’s worth mentioning that the sun isn’t the only problem. ANY infrared source could be problematic, including stage lighting which might be used above the field (depending on event). Any light source that also generates palpable heat (at a reasonable distance), would likely affect these (and any other IR) sensors


Thank you for the input . We will keep that in mind next time we are choosing sensors .

To echo what’s said above, our team has failed to use these sensors in past competitions. When we looked at the root cause, we found that certain stadium lightings emit a much wider spectrum than others. I would highly recommend either understanding if you’re competitions have this wide spectrum lighting or invest in a different solution.

We also found this issue with sunlight. Our sensors were mounted to the outside of polycarbonate with a hole to allow the beam to pass through clearly. Under the right conditions the polycarb will funnel the outside light and cause interference with the beam (think fiber optics). We were able to black out the edges of the hole with paint or nail polish to reduce this problem.

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We managed to overcome any interference with these sensors by creating little two-part 3DP mounts that have a small inset cone to reduce outside interference. If anyone is interested I could throw the files up on GrabCad after work.


Please do. We’re using these sensors and we’ll have to worry about sunlight even at our competition.

Sensors are very important, don’t use cheap ones.

Look for a sensor that has BGS (Background Suppression) technology. Use a quality industrial sensor like those from Banner Engineering Banner Engineering

You can also avoid some of the ambient light issue using a hood or visor on the sensor. A piece of PCV pipe will work. Line the inside with dark Gaff tape.


Here’s our mounts that we’ve been using with no problem. Let me know if they work for you!

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We have the same setup - not conducive to shrouds but we can definitely try the nail polish. Thanks !

We used those sensors in 2020. The robot worked great on our field but when we got to Miami Valley they acted up because of the lighting. We had small holes in each sides of our smoked polycarbonate snake that lined up the sensors. Once we figured out it was the lights, we took small plastic spacers (think small VEX axle spacers) and lined the holes to cut down the noise. Problem solved.

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