Abstract: A microscope objective that is achromatic, so that deviations in focus do not arise with visible light and ultraviolet light (particularly light in the vicinity of wavelength=266 nm), and which can satisfactorily observe a specimen. The microscope objective is made of at least three types of glass materials, of which one type is barium fluoride.

Abstract: This invention relates to a microscope objective lens system a part of which is immersed in a liquid to observe a sample present in the liquid. Particularly, this invention provides an apochromat-grade microscope objective lens system which can be machined cheaply and easily by the conventional technology, which is well corrected for chromatic aberration, and which is excellent in flatness of the image plane. This objective lens system has a plane-parallel plate on the most sample side, is constructed without using an embedded lens as used in the conventional objectives, and can take a variety of lens layouts.

Abstract: A plan apochromatic microscope objective lens is disclosed having few constituent lens elements, a large numerical aperture, excellent flatness across the entire field of view of the objective lens, and a relatively long working distance. The objective lens comprises, in order from the object side, first, second, and third lens groups. The first lens group comprises a meniscus lens having a concave surface oriented toward the object side, and a positive meniscus lens having a concave surface oriented toward the object side. The second lens group comprises a simple lens, a cemented lens including a negative lens and a positive lens, and a cemented lens including a positive lens and two negative lenses. The third lens group comprises a cemented lens with overall weak refractive power and including a positive lens and a negative lens. The objective lens satisfies a number of conditional expressions.

Abstract: This invention relates to a microscope objective lens system a part of which is immersed in a liquid to observe a sample present in the liquid. Particularly, this invention provides an apochromat-grade microscope objective lens system which can be machined cheaply and easily by the conventional technology, which is well corrected for chromatic aberration, and which is excellent in flatness of the image plane. This objective lens system has a plane-parallel plate on the most sample side, is constructed without using an embedded lens as used in the conventional objectives, and can take a variety of lens layouts.