optical air vane modification

[FreshMar at aol.com]

Hello.
I have a Bosch vane- type air flow sensor that's got a bad resistor pad. 
I am thinking of changing this position- metering system to an optical 
with varied- opaqueness moving disc. So instead of the air vane moving an 
arm across the resistor pad , a physically wearing part(and a damn noisy 
input) , it will rotate a round disc with either a dot-system or a grey- 
scale variable opaqueness in between an emitter and sensor pair. My 
questions include : will this type of system afford enough range and 
resolution for this application, has anyone tried this, and am I out of 
my mind?
 ...Thousands of questions...
Mario T.