Hi,
I’m looking for a high-power/narrow band infrared led to use as a transmitter for a beam-break detector using an arduino-like microcontroller.
My understanding is that the transmitter is the main limiter for distance. The best options I’ve seen so far are 38kHz leds for this type of job.
I’m hoping to get 10m+ range on the beam with a reflector in the middle so the transmitter and receiver can be in the same unit. I know it is pushing the limits of such a device and it may not be possible, but the more range I can get the better.
You’re definitely on the money in that it needs to be modulated to avoid interference from ambient light. We’ve got receivers in our range for that, but no LEDs that modulate directly (An Arduino should be up to the task of that though):
Though I’m not sure we have any LEDs in our range that are bright enough (though you can certainly try a bunch of them in an array and see how you go), and would suggest a cleaner solution would be a LIDAR sensor and a button to “zero” the code on an Arduino, and any distance you get back well under the zero value counts as a “broken beam”
The only catch is that their quoted 12m range is usually reduced depending on the reflectivity of the material the light is reflected off.
You can brute force it with more money and lasers if you need crazy range, though:
The thing to keep in mind is most of these sensors communicate over serial, and at 3.3V, so if you want to use an Arduino, pick a 3.3V one, or get a logic level converter, and try to pick an Arduino with a spare serial port (one with native USB like on based on the 32u4).
Let us know what you think of that as an idea, or whether you end up experimenting with pulsed LEDs!
Those reflectors should do ok as they are ‘corner reflectors’ - i.e. the internal ‘facets’ are actually each comprised of three mirrors that are mutually perpendicular to each other - such that any inbound ray, will reflect directly back to the original direction, due to the nature of the possible ‘bounces’ between the surfaces.
Similar arrangements are also used in the RF field as reflectors for radar targets etc. (sometimes called retro-reflectors)
