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I'm working on a project that utilizes an array of IR sensors and recievers to map objects directly in front of it. This is similar to the various interactive coffee table setups that light an LED when something is close to it (via reflection of the IR light).

Now, I'm creating this array and putting it directly underneath a sheet of acrylic (or some other opaque material), so that when something is directly on top of the sheet it will pick it up. This makes the design easier, because my working range for the sensors is small and short (like 1 cm).

With that being said, I'm trying to figure out which IR emitters and sensors to use that will efficiently achieve this. I've been looking at SMDs because size is a factor, and I was hoping to use this emitter and this sensor, but I have some concerns.

This emitter is small and considerably weaker than those used in other emitters used in sensors (like the TCRT5000), and I don't even know how to compare the phototransistors, but given the very small range and somewhat controlled conditions, I was hoping it would work well to not only save space but to limit the noise of everything not directly on top of the acrylic.

I just need to know if this setup could work so that I can order them and start testing them, but if I'm not even close I'd rather try something else. If anyone has any tips for choosing these emitters and sensors, that would be great.

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  • \$\begingroup\$ First, your emitter and sensor links both connect to the emitter data sheet. Second, since the emitter data sheet makes no mention of actual intensity levels produced, there is no way to determine whether or not the combination would work. \$\endgroup\$ – WhatRoughBeast Sep 4 '15 at 14:03
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I would not use an IR LED/transistor because:

1) You need to take care of modulation and detection of the signal yourself

2) If you do not do the above correctly you will have problems with false detections from sunlight or even just indoor lighting

3) Even if you get everything above right you still have to set up a mechanical barrier between IR LED and transistor to prevent crosstalk, and you have to do all the crosstalk compensation yourself, taking into account reflection of the cover glass

If this is a somewhat serious project I would use an integrated IR detection module such as the Vishay VCNL4010 which will take care of all of the above for you. It can be controlled via I2C. If it's just a hobby project then by all means do it with an IR LED/transistor pair - it will be a good learning experience.

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  • \$\begingroup\$ Very good recommendation, thank you. This is an ideal module that I didn't even know existed (despite how much time I went into trying to find it). Would you happen to know of any other devices that I might be able to consider? I will most definitely be testing this one, but I would like to try different, possibly less expensive, devices as well. \$\endgroup\$ – Nathan Margaglio Sep 4 '15 at 12:45
  • \$\begingroup\$ This was the only one I could find for my project that had an integrated IR LED. I believe I found other options but they all required an external IR LED which in turn requires you to set up your own mechanical barrier for crosstalk prevention. With the VCNL4010 you can even control the IR current yourself and there are very convenient breakout boards from e.g. Sparkfun that work with Arduino for easy testing of the chip. \$\endgroup\$ – David Högberg Sep 4 '15 at 12:56
  • \$\begingroup\$ @NathanMargaglio well recommendations are off topic, and I'm not 100% sure I understood what you are trying to do, but ST VL6180X is a proximity detector as well. \$\endgroup\$ – Arsenal Sep 4 '15 at 13:49

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