In an early version of the cam Control device (before the drop Controller) I used an interrupter/ opt isolator to detect the water drops. The plan was to detect the water drop, wait a little bit and then activate the shutter.

CNA1015 series is a transmissive photosensor series in which a high efficiency GaAs infrared light emitting diode is used as the light emitting element, and a high sensitivity phototransistor is used as the light detecting element. The two elements are arranged so as to face each other, and objects passing between them are detected.

Features:

Position detection accuracy : 0.3 mm , Gap width : 5 mm & The type directly attached to PCB.