I have one of Pololu 38 kHz IR Proximity Sensors (Fixed Gain, High Brightness). I am able to detect 15-30 cm distances with it by changing potentiometer on it. But it cant detect beyond that. I suspect that maybe the sensor i have is not actually High Brightness model but Low one.
I supply my sensor with 5V and analog output is directly connected to my controller’s ADC pin without any component in-between connected to drive. I have tested mostly with my hand and paper (where i realise that paper detection is bit better).
I also wonder what is the best conditions for IR sensor to detect highest distance with best performance, with what kind of reflection surface and what kind of ambience?
I am sorry you are not getting the range you expect for that proximity sensor. It is difficult to determine which version of that sensor you might have without specialized electronics instrumentation or knowing your salesorder information. However, if you have the 60cm version, you should be able to detect up to 60cm if the frequency of the IR emitter LED is tuned to 38kHz. Turning the trimmer potentiometer adjusts the frequency of the IR emitter LED, which effectively adjusts the maximum sensing distance of the sensor. So, it might be that you inadvertently adjusted the pot to lower the sensing distance. Can you remove the IR sensor from your setup, supply power to it, and try turning the potentiometer again to increase the range at which the sensor detects as far as it can go? Like we mention on the product page for those sensors, they can be triggered by ambient IR (e.g. from fluorescent lights), so some optical shielding, such as by having the sensor mounted receiver-side-down when fluorescent lights are above, might mitigate this. You could also turn off the lights in a room while performing that test. Also, you should use a large, flat, object with high reflectivity to IR light as your object to detect. For example, a white-painted wall or sheet of 8.5" by 11" paper (stiffened by cardboard would help) would work fine.
