A detection mark comprising a pattern formed from a thin phosphor layer which emits a light having a different wavelength from that of an excitation light irradiated on a surface side of the phosphor layer, and an undercoat layer which is formed on a rear surface side of the phosphor layer and reflects...http://www.google.se/patents/US5210411?utm_source=gb-gplus-sharePatent US5210411 - Detection mark and method and apparatus for detecting mark
