Abstract: An objective lens system with protection glass for a microscope and having a numerical aperture of 1.25 and using an immersion oil, having a first, second, third and fourth lens groups, the first lens group being a plano-parallel plate cemented to a hemispherical lens, the second lens group being one aplanatic meniscus, the third lens group being three cemented doublets, and the fourth lens group being two lens components including a positive and a negative meniscus component which are arranged with their concave surface opposite each other. The objective lens system has a relatively small number of lens components, and the aberration, especially chromatic, spherical, coma, astigmatic difference and curvature of field, are corrected favorably.

Abstract: An objective lens system having a first and a second lens group that are separated by a gap where a ray bundle between the first and second lens is substantially telecentric and the second lens group has two lens elements that are also separated by a gap. The first lens element in the second lens group is a positive optical power lens and the second lens element in the second lens group is a negative optical power lens. The objective lens system has a relatively small number of lens elements and the aberration, including chromatic, spherical, coma, astigmatic difference, and distortion, are favorably corrected. In one embodiment, the objective lens system is used in a plan-achromatic microscope objective lens having a numerical aperture of 1.25 to 1.30 with a Petzval sum of 0.1. In a second embodiment, the objective lens system with is used in an achromat microscope objective lens with improved resolution and a greater than 50% transmittance of light at a wavelength of 340 nanometers.

Abstract: An objective lens system for a microscope having a power of .times.16 to .times.24 and including first, second and third lens groups, the first lens group being a comparatively thick meniscus lens component, the second lens group being a biconvex positive cemented triplet consisting of a biconvex first lens component, a biconcave second lens component and a biconvex third lens component, and a third lens group being a two lens system including a biconvex positive singlet and a negative thin meniscus lens component, or a negative and a positive thin meniscus lens components, or a positive cemented doublet, and having a relatively small number of lens elements, with its aberration (especially spherical, astigmatic difference, curvature of field and chromatic aberrations) being favorably corrected.