PURPOSE: To compensate aberrations 'while ensuring a wide exposure region and a large numerical aperture and making both sides telecentric by specifying the refractive powers, focal distances and a composite focal distance of plural lens groups.
CONSTITUTION: The refractive powers of a first to a sixth lens groups G1-G6 arranged in order from the object side are made positive, negative, positive, negative, positive and positive, the second lens group G2 includes a front lens L2F whose concave surface confronts the object side having a negative refractive power, a rear lens L2R whose concave surface confronts the object side having a negative refractive power and an intermediate lens group G2M arranged between these lenses. The conditions: 0.1<f1/<f3<17, 0.1<f2/f4<14, 0.01<f5/L<0.9, 0.02<6/L<1.6, 0.01<fn/f2<2.0 are satisfied, where f1-f6: focal distances of the first to the sixth lens groups G1-G6, fn:the composite focal distance of the second lens to the fourth lens having negative refractive powers in the second lens group G2 and L: a distance from an object R as a projecting objective to an object to be projected W such as a substrate.
ISHII MIKIHIKO
TANAKA KAZUMASA
Next Patent: CATADIOPTRIC SYSTEM AND OPTICAL DEVICE USING THE SAME