Alignment systems

Apparatus for aligning two objects each having at least one reference mark on a surface thereof, whereby alignment of the objects is indicated by alignment of corresponding reference marks on the surfaces of the objects, the apparatus comprising:

• support means for supporting the objects in use with the said surfaces facing one another;
• imaging means, mounted for movement between the said surfaces in use, for acquiring, on a single imaging surface thereof, simultaneous images of respective areas of the surfaces of the objects, which areas contain corresponding reference marks;
• control means for determining the locations of the reference marks in the images and determining therefrom the extent of misalignment of the objects, the control means being arranged for controlling movement of the imaging means such that, in use, the imaging means moves along a path along which the imaging means views the or each pair of corresponding reference marks, the or each pair of simultaneous images being acquired as the imaging means moves along the path;
• stroboscopic lighting means, responsive to the control means, for instantaneously illuminating the surfaces of the objects to enable the imaging means to acquire the or each pair of simultaneous images as the imaging means moves along the path;
• and
• means, responsive to the control means, for adjusting the relative positions of the objects to bring the objects into alignment.