Patent ID: 7486394

Claim:
A measuring head ( 4 ) for the optical measurement of a workpiece ( 2 ), comprising, a light source ( 8 ) for generating light having different spectral components, a light receiver ( 9 ) for receiving light reflected from the workpiece ( 2 ) and for analyzing the light concerning its spectral composition, at least one object lens ( 27 ) for receiving generated light from said light source( 8 ) and for directing the generated light onto the workpiece ( 2 ) and for receiving light reflected from the workpiece ( 2 ) and for re-directing the reflected light from the workpiece ( 2 ) for reception by the light receiver ( 9 ), at least one optical wave guide ( 6 ) for optically connecting said light source ( 8 ) and said light receiver ( 9 ) with said at least one object lens ( 27 ), said at least one object lens ( 27 ) having a diameter less than 5 mm, said at least at one object lens ( 27 ) comprises: a. a mirror ( 24 , 34 ) for deflecting the light delivered by the optical wave guide ( 6 ) in a direction transverse to the optical wave guide ( 6 ); b. at least one first focusing element ( 23 , 33 ) disposed before said mirror ( 24 , 34 ) as viewed from the light source ( 8 ); c. a second element ( 26 , 36 ) having a chromatic aberration and arranged in the light path of the object lens ( 27 ) in series with the first focusing element ( 23 , 33 ) and behind the mirror ( 24 , 34 ) or which is integrated with the mirror ( 24 , 34 ), wherein the object lens ( 27 ) has a total numeric aperture (NA) equal to or greater than 0.1.