| 摘要 |
<P>PROBLEM TO BE SOLVED: To favorably correct axial chromatic aberration in a wide range, favorably correct field curvature, have brightness and high aperture efficiency, favorably correct various aberrations, acquire a high contrast in a high spatial frequency area, and acquire favorable performances. <P>SOLUTION: The readout lens has a five-group and eight-element configuration by sequentially disposing from an object side: a first-group lens system G1 comprising a positive first lens system E1; a second-group lens system G2 formed by joining a positive second lens system E2 and a negative third lens E3 and having a negative refractive power as a whole; a third-group lens system G3 formed by joining a positive fourth lens E4 and a negative fifth lens E5 and having a positive refractive power as a whole; a fourth-group lens system G4 formed by joining a negative sixth lens E6 and a positive seventh lens E7 and having a negative refractive power as a whole; and a fifth-group lens system G5 comprising a positive eighth lens E8. An aperture is provided between the third-group lens system G3 and the fourth-group lens system G4. <P>COPYRIGHT: (C)2012,JPO&INPIT |
