Position determination method and element

A position determination method for determining a position of a point on a flat surface by observing the position of the point and a position of a fiducial portion on the flat surface in an image of a measuring system provided with an imaging optical system using coaxial episcopic illumination, the fiducial portion being in the shape of a pillar at least in the basal portion and being provided with an inclined surface surrounding the foot of the pillar, the position determination method comprising the steps of:

• determining a position of the outer boundary of the foot from the boundary between the inclined surface surrounding the foot and the flat surface in the image of the measuring system;
• determining the position of the fiducial portion from the position of the outer boundary of the foot;
• and
• determining the position of the point with respect to the position of the fiducial portion.