Patent ID: 7076021

Claim:
Apparatus for measurement of the thickness of thin layers by means of X-rays using an X-ray tube ( 12 ) which emits X-rays which are directed at a layer to be measured, comprising having at least one aperture apparatus ( 17 ) arranged between the X-ray tube ( 12 ) and the layer to be measured, wherein the at least one aperture apparatus comprises an area ( 26 ) absorbing X-rays and has at least one aperture opening ( 28 ), wherein said at least one aperture opening ( 28 ) wherein the absorbent area ( 26 ) surrounds said at least one aperture opening ( 28 ), and in the at least one aperture apparatus ( 17 ) has a geometric shape which, seen in the beam direction, projects an area which at least in places is matched to the geometry of the layer to be measured, and wherein at least one inner absorbent area ( 29 ) is provided within said at least one aperture opening ( 28 ) or is at least partially adjacent to said at least one aperture opening ( 28 ), by means of which at least one through-opening ( 33 ) is formed in said at least one aperture opening ( 28 ).