| CPC G01J 3/0224 (2013.01) [G01J 3/0262 (2013.01); G01J 3/42 (2013.01); G01J 3/46 (2013.01); G01J 3/0229 (2013.01); G01J 3/10 (2013.01); G01J 3/28 (2013.01); G01N 21/255 (2013.01); G01N 21/474 (2013.01)] | 19 Claims |

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1. Apparatus for determining a colour of a translucent material, the apparatus comprising:
a first light source configured to illuminate a translucent material at a first surface location;
a second light source configured to illuminate the translucent material at a second surface location spaced apart from said first surface location; and
a light spectral sensor configured to detect both first light originating from said first light source and second light originating from said second light source, wherein the first light and second light are both detected at said first surface location,
the apparatus being configured to operate the first and second light sources alternately, wherein the first light detected at said first surface location by the light spectral sensor and originating from said first light source is principally light diffusely reflected from said first surface location, whilst the second light detected by said light spectral sensor at said first surface location and originating from said second light source is principally light scattered by scattering centres in an interior of the translucent material,
the apparatus further comprising:
a processor for combining light spectra detected by the light spectral sensor at said first surface location whilst operating each of the first and second light sources, to provide a combined light spectrum indicative of the colour of the translucent material.
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