Abstract: A vacuum optical system has a vacuum chamber for housing an optical system used In a vacuum. The vacuum chamber is equipped with a member, on which the optical system is at least mounted, supported by such parts that when a pressure in the vacuum chamber changes to deform the vacuum chamber, the amount of displacement transmitted to the optical system is smaller than a predetermined tolerance depending on an accuracy necessary for the optical system. Thus, the vacuum optical system can be obtained which does away with the need for readjustment of optical alignment and is compact.

Abstract: A sample vessel for X-ray microscopes comprising a first silicon base plate having an entrance window covered with a thin film of silicon nitride, and a second silicon base plate which has an exit window covered with a thin film of silicon nitride and matched with the entrance window. The second silicon base plate being connected the first base plate by way of a spacer so as to form a sealed space capable of accommodating samples to be observed. Disposed in the space is a mesh member made of a wire material having an angle of contact with water smaller than 90.degree. at a location adjacent to the thin film of silicon nitride covering the entrance window or a thin film of aluminium is evaporation-coated over the thin film of silicon nitride.

Abstract: In a soft X-ray microscope including a soft X-ray source for emitting soft X-rays, a condenser lens for focusing the soft X-rays onto a specimen under inspection, an objective lens for focusing soft X-rays emanating from the specimen, a soft X-ray detector for receiving the soft X-rays focused by the objective lens, and a visually observing optical system for forming a visible image of the specimen by converting an optical property of the specimen other than contrast and color into a contrast in brightness or color. The visually observing optical system may be formed as phase contrast microscope, dark field microscope, polarizing microscope, differential interference microscope, or fluorescent microscope. Then, alignment and focus adjustment can be performed by observing the visible image of the specimen without irradiating the specimen with the soft X-rays even if the specimen has substantially no contrast and color.

Abstract: A vacuum optical system has a vacuum chamber for housing an optical system used in a vacuum. The vacuum chamber is equipped with a member, on which the optical system is at least mounted, supported by such parts that when a pressure in the vacuum chamber changes to deform the vacuum chamber, the amount of displacement transmitted to the optical system is smaller than a predetermined tolerance depending on an accuracy necessary for the optical system. Thus, the vacuum optical system can be obtained which does away with the need for readjustment of optical alignment and is compact.