I have a project involving the detection of the presence of water in a cylindrical transparent plastic container (diameter=25cm)
And I cannot put any device inside, so I was thinking of using and IR LED and IR sensor so do you think this is possible ?
How can I make the difference when the container is empty (contains air) and when it has water ?
How does infrared light behave in both cases?
Also will the plastic body of the container interfere ?
Basically, if we omit the plastic(as it'll have static value), will the intensity of ir light decrease when passing through water(compared to air) ? how much percent ?
Best Answer
In general, what you would need to know to completely calculate the situation through, is the wavelength-dependent absorption of your plastic and water and the characteristics of your LED (wavelength, spectral broadness, etc.). And yes, in general, most plastics have IR-absorption (which is why IR spectroscopy is used in plastic analytics). But depending on your plastic, there might still be enough coming through to detect a signal. According to an arbitrarily googled source (here), water has absorption in the IR-regime. Whether the signal difference is big enough will depend on your plastic wall thickness and the material, BUT in the end, if you can, try it - or try to obtain better data on your materials and apparatus.