摘要 |
A projection optical system, which is telecentric with respect to an object side and an image side, projects a pattern onto an image plane, which is substantially parallel with the pattern, at a substantial equi-magnification. The projecting optical system is provided with first and second condenser lenses having a common (first) optical axis which is perpendicular to the pattern and the image plane. The projection optical system further includes an imaging lens having a second optical axis that intersects with the first optical axis at an intermediate position between the first and second condenser lenses. A first mirror reflects a beam from the pattern and passed through the first condenser lens toward the imaging lens. A second mirror reflects the beam passed through the imaging lens to the imaging lens, and a third mirror reflects the beam passed through the imaging lens toward the second condenser lens.
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