sensing a part

Hi all,

I feed a part and then want to detect the end of the part so as to
zero to the end of the part.

I am only trying to find one side, not both X and Y or X/Y/Z axisies.

The part is 1 inch round. I was thinking of putting some type of
sensor to detect the edge and need to be within a few thou, (no more
than 5 thou off)

I was hoping I could use a proximity or capatance or even a photo
detector of some sort.

The part passes thru so I cannot use an end switch.

any suggestion ?

Dave