Reflection issue of Pololu IR beacon

we are playing around the Pololu IR beacons, and found such a bit abnormal issue during inital test:
when the IR receiver unit is put in corner or near to certain barrier, walls etc., the red led on this unit located farthest away from the emmiter unit will get lighted, although theorecically only the nearest red LED should get lighted … we tried a lot of times, yet this phenomenon is sticky and frequently observed.

The only reason I can guess is the reflection from the barrier, yet this is still tricky since in this case the IR beam travels a longer way to arrive at the farther receiver than directly to the nearer one, and the signal strength thus should be weaker…

Have a feeling that adding certain shielding for IR receiver could make it more reliable.


The beacons were designed for a generally open environment. The sensors can detect IR from all sides, and apparently, the signal from the back side of the detector plus the reflected signal from the front is stronger than just the direct signal to the front. In this case, the only thing I can recommend is some shielding so that the sensors can only see IR from their front sides.

- Jan