A method and apparatus for detecting fiducial marking on a material are disclosed.
The fiducial marking is characterized by the ability to absorb light in a first
wavelength range and to fluoresce in a second wavelength range that is outside
the first wavelength range. An excitation source is configured to direct light
at the material in the first wavelength range, to cause the fiducial marking material
absorb the light in the first wavelength range and to fluoresce in the second wavelength
range. A detection device is located at a predetermined site and is configured
to optically examine the material at the predetermined detection site, to determine
whether fluorescence from the fiducial marking which is in the second wavelength
range is detected at the predetermined detection site.
