This is the high resolution wind speed sensor based on an optical reflective interrupt sensor. The little black chip on the round sensor board is an IR transmitter and receiver. The white face of the interrupter wheel reflects the beam back and a pulse is created. Eight pulses per revolution provide enough resolution to resolve wind speeds at 0.1 MPH with a 1 second measure interval.
The mechanical parts consist of a housing and axle that runs in a bronce shaft. The axle has a steel bearing at the bottom end which runs on a sapphire plate that’s mounted on the PCB. This provides a near friction less arrangement since only the very tip of the ball makes contact with the sapphire plate, while maintaining the correct distance for the interrupter wheel at all times.
See the download section for specs.