Abstract: An infinity-corrected microscope objective lens has, arranged in order from the object side along an optical axis, a first lens group having a positive refractive power, and a second lens group having a positive refractive power, an intermediate image forming plane in which light from an object forms an image being positioned between the first lens group and the second lens group, and the microscope objective lens satisfying the condition below. ?0.2<f×NA/TL <0.05, where f is the focal length of the microscope objective lens, NA is the object-side numerical aperture of the microscope objective lens, and TL is the distance on the optical axis from the lens surface of the microscope objective lens on the side thereof closest to the object to the lens surface of the microscope objective lens on the side thereof closest to the image.

Abstract: A particularly constructed objective lens unit is provided for reflective fluorescence that transmits excitation light well, generates little self-fluorescence, and can correct for various aberrations. The objective lens unit has a front lens group closer to a specimen side than a rear lens group. Among the lens components forming the front lens group, at least the lens components arranged on the specimen side are formed from a prescribed optical material. This optical material has a higher transmissivity for excitation light and generates less fluorescence due to the excitation light than the other lens components forming the objective lens unit. The excitation light, fed into a position path between the front lens group and the rear lens group, is guided through the front lens group to the specimen. An image of the specimen is formed, based on the fluorescence from the specimen, through the front lens group and the rear lens group.

Abstract: A microscope for observing a specimen immersed in an immersion liquid within a specimen container includes an objective lens and utilizes a sealed container containing a second liquid that has substantially the same refractive index as the immersion liquid. The sealed container is positioned between the objective lens and the specimen. Alternatively, the microscope for observing the specimen immersed in the immersion liquid can utilize a container opening toward the objective lens. A method of observing the specimen includes the steps of positioning a container containing a liquid, with substantially the same refractive index as an immersion liquid within a specimen container, between a microscope objective lens and the specimen and observing the specimen through the objective lens.

Abstract: Fluid-immersion microscope objective lenses are disclosed having simple construction, good image-plane flatness and ease of manufacturability. The most objectwise lens surface intended to contact the immersion fluid during use has a negative refractive power, and is preferably concave. The objective lens satisfies certain quantitative criteria.