A universal read head for a tank-level float gauge is adapted for use with any of certain different types of gauge rods which may be connected to a float element in the tank, including rods having an optical code thereon including a plurality of alternating reflecting and non-reflecting stripes arranged...http://www.google.com/patents/US5874899?utm_source=gb-gplus-sharePatent US5874899 - Tank level gauge and sensor head therefor
