| 摘要 |
PURPOSE:To obtain a small-sized, lightweight condenser lens with high performance which has off-axis aberration compensated excellently by forming aspherical surfaces as surfaces of 1st and 2nd lenses on light source sides and satisfying specific conditions. CONSTITUTION:This condenser lens consists of the 1st lens 1 with positive refracting power and the 2nd lens 2 with positive refracting power in order from the light source side. Then the surfaces of the 1st lens 1 and 2nd lenses 2 on the light source sides are made aspherical and 0.5<R1/f<2 and 1.1<d1+d2+d3<2 are satisfied. Here, R1 is the radius of curvature of a 1st surface of the 1st lens 1 nearby the optical axis, (f) is the focal length of the whole system, and di (i=1-3) is an (i)th on-axis gap counted from the light source side and a value standardized with the focal length (f). Consequently, the high-performance condenser lens is obtained by using two relatively thin positive lenses.
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