MICROSCOPIC OBJECTIVE LENS WITH LOW MAGNIFICATION

摘要

PURPOSE: To provide a microscopic objective lens with a low magnification having a magnification of about 1.5×, a numerical aperture of about 0.045, excellent on-axis performance and off-axis performance and well compensated pupil aberration and the chromatic aberration of the pupil. ;CONSTITUTION: This lens is constituted of a first group G1 having a convex positive lens on the object, side, a second group G2 having a concave negative lens on the object side, a third group G3 having a joined lens of a negative and a positive lenses and a fourth group G4 having a convex positive lens on the image side. It is preferable that a composite distance D₂ from the surface of the object to the surface of the negative lens of the second group G2 on the object side and a composite distance D from the surface of the object to the final surface of the objective lens satisfy the condition: 0.15D₂/D0.45 and the third group comprises the joined lens of three negative, positive and negative lenses. The Abbe number νI of the positive lens having a convex surface on the object side in the first group G1 and the Abbe number νII of the negative lens having a concave surface on the object side in the second group G2 preferably satisfy the conditions: νI35, νII55.;COPYRIGHT: (C)1995,JPO