I am trying to find a motion sensor that can detect a drop of water from a distance of about 10 feet or more without a reflector behind it. It is the big hurdle in a project I am working on. Does anyone have any ideas or places I could go for something like this? I am assuming a laser would be needed for something not only that small, but that far away. I have looked into ultrasonic with no good leads. I am open to any suggestions. I am by no means set on a laser.