Homemade anemometer

This parts are used to build a homemade anemometer with an Arduino and an optical sensor.
The complete project (in french) can be found here : http://thegoodwire.fr/article.php?articleId=17

A short explanation of the principle of the anemometer:

It's a cup anemometer that use three buckets to convert linear wind speed to rotational speed. Cups are attach on an axis (a 8mm threaded rod) so we will like to know the speed of this axis. In the box a wheel with five spokes is maintained on axis by two nuts. In front of the wheel's spokes it was a optical sensor. A cheap sensor use to measure distances, it send an electrical tension between 0V (long distance) and 5V (very short distance). I have connected the sensor on an Arduino, when a spoke enter in the field of the sensor the micro-controller detect a variation of the distance measured by the sensor. Same when the spoke exit the field we detect an another variation of the sensor information. The Arduino count this variations duri