| 摘要 |
An objective lens system ( 2 ), particularly for a fingerprint reader apparatus, said lens system ( 2 ) comprising a first lens ( 8 ) formed as a condensing lens guiding light beams arriving from an object generally telecentrically, an aperture stop ( 9 ) having a centre (P) and being located in the vicinity of a focal point of the first lens ( 8 ), a correcting second lens ( 10 ) arranged between the first lens ( 8 ) and the aperture stop ( 9 ) and juxtaposed with the aperture stop ( 9 ), and a correcting third lens ( 11 ) formed as a condensing lens and arranged beside the aperture stop ( 9 ) opposite the second lens ( 10 ). According to the invention, the second lens ( 10 ) is a condensing lens with a spherical surface (S<SUB>3</SUB>) facing the first lens ( 8 ), wherein the curvature centre of the surface (S<SUB>3</SUB>) is at a distance shorter than 15% of the curvature radius of the surface (S<SUB>3</SUB>) from the centre (P) of the aperture stop ( 9 ), and the aperture stop ( 9 ) is arranged at a distance shorter than 25% of the focal length of the first lens ( 8 ) from the focal point of the first lens ( 8 ). |
