Apparatus for determining mutual positional relationship of plural patterns in a single viewing field

An apparatus for detecting mutual positional relationship between a first pattern and a second pattern in a first viewing field and mutual positional relationship between a third pattern and a fourth pattern in a second viewing field, comprising:

• a first objective lens covering a first viewing field containing the first and second patterns of which mutual positional relationship is to be determined;
• a first beam splitting member provided between said first objective lens and a first image focusing plane for splitting a light beam containing information of the first and second patterns into a first light beam and a second light beam respectively advancing along first and second optical paths;
• a first beam recombiner for reuniting the first and second light beams and thus forming on the first image focusing plane a first image of the first and second patterns by the first light beam passing along the first optical path and a second image of the first and second patterns by the second light beam passing along the second optical path;
• first image displacing means provided at least in one of the first and second optical paths for mutually displacing the second image of the first and second patterns formed by the second light beam passing through the second optical path with respect to the first image of the first and second patterns formed by the first light beam passing through the first optical path so as to bring the second image to a position predetermined with respect to the first image;
• first detecting means for detecting the amount of displacement performed by said first image displacing means, whereby the mutual positional relationship between the first and second patterns is determinable from the amount of the displacement;
• a second objective lens covering a second viewing field containing the third and fourth patterns of which mutual positional relationship is to be determined;
• a second beam splitting member provided between said second objective lens and a second image focusing plane for splitting a light beam containing information of the third and fourth patterns into a third light beam and a fourth light beam respectively advancing along third and fourth optical paths;
• a second beam recombiner for reuniting the third and fourth light beams and thus forming on the second image focusing plane a third image of the third and fourth patterns by the third light beam passing along the third optical path and a fourth image of the third and fourth patterns by the fourth light beam passing along the fourth optical path;
• second image displacing means provided at least in one of the third and fourth optical paths for mutually displacing the fourth image of the third and fourth patterns formed by the fourth light beam passing through the fourth optical path with respect to the third image of the third and fourth patterns formed by the third light beam passing through the third optical path so as to bring the fourth image to a position predetermined with respect to the third image;
• and
• second detecting means for detecting the amount of displacement performed by said second image displacing means, whereby the mutual positional relationship between the third and fourth patterns is determinable from the amount of the displacement.