Pulse Counter with optic sensor

[gohvan]

Hello,

I'm searching for a circuit which has an optic reflective sensor which creates a pulse when senses a change of color, and then is connected to a pulse counter.
The main idea is trying to obtain the counting of a water meter which is totally mechanic. So, the sensor would be pointed to one of those pointers that rotates when the water is passing through the water meter, and every time the pointer with pass through the sensor's beam, the circuit would create a pulse and the counter would register it.

Is there something like that available on the market?

[Pauldf]

I'm wondering if you'd get away with bouncing an IR beam off the back of the dial so the pointer breaks this reflected beam. The beam can be counted by a receiver and pulse counter circuit.