Abstract: The hot dip galvannealed steel sheet of the present disclosure has a base steel sheet and a plating layer. The base steel sheet has a predetermined chemical composition by mass %. An existence ratio ER of internal oxides identified under predetermined conditions by observation of the cross-section of the base steel sheet is 40% or less and an interval I of internal oxides is 300 ?m or more. The hot dip galvannealed steel sheet of the present disclosure is excellent in appearance etc.

Abstract: The hot dip galvannealed steel sheet of the present disclosure has a base steel sheet and a plating layer. The base steel sheet has a predetermined chemical composition by mass %. A standard deviation SD of Mn intensities found utilizing EPMA under a predetermined Condition 1 is 0.40 or less while an interval I of concentrated Mn parts found utilizing EPMA under a predetermined Condition 2 is 50 ?m or less. The hot dip galvannealed steel sheet of the present disclosure is excellent in appearance etc.

Abstract: A microscope optical system comprises an objective lens and an intermediate magnification varying part disposed just after the image side of the objective lens. A microscope objective lens according to another aspect of the invention comprises a first lens group and a second lens group in the mentioned order from the object side. The first lens group includes a positive meniscus lens with the concave surface facing the object side and one or more cemented lenses, the first lens group having a positive refractive power as a whole, at least one of the cemented lenses includes a lens made of a material having an Abbe's number equal to or larger than 80, and conditions 0.3?wd/f?0.45 and 0.6?NA are satisfied, where f represents the focal length of the microscope objective lens as a whole, wd represents the working distance of the microscope objective lens, and NA represents the numerical aperture of the microscope objective lens.

Abstract: A catadioptric optical system comprising a first imaging optical system for forming an intermediate image of a first plane surface, a second imaging optical system for forming a final image of the first plane surface onto a second plane surface which is substantially parallel to the first plane surface, and a catadioptric type optical system disposed in the optical path from the first plane surface to the second plane surface and including a first reflecting surface which reflects light coming from through the first plane surface and a second reflecting surface for directing the light reflected by the first reflecting surface toward the second plane surface. At least one of the first and second reflecting surfaces is a concave reflecting surface. All of the optical elements of the catadioptric optical system are disposed on a single linear optical axis.

Abstract: A microscopic illumination apparatus to be applied to a microscope selectively using plural types of objective lenses having different magnifications comprises a light source, a collector lens for making a light flux emitted from the light source a substantially parallel light flux, and at least two fly-eye lenses disposed side by side along the optical axis at the back of the collector lens. A space between the two fly-eye lenses is variable in accordance with an objective lens to be used in the microscope.

Abstract: A microscope optical system comprises an objective lens and an intermediate magnification varying part disposed just after the image side of the objective lens. A microscope objective lens according to another aspect of the invention comprises a first lens group and a second lens group in the mentioned order from the object side. The first lens group includes a positive meniscus lens with the concave surface facing the object side and one or more cemented lenses, the first lens group having a positive refractive power as a whole, at least one of the cemented lenses includes a lens made of a material having an Abbe's number equal to or larger than 80, and conditions 0.3≦wd/f≦0.45 and 0.6≦NA are satisfied, where f represents the focal length of the microscope objective lens as a whole, wd represents the working distance of the microscope objective lens, and NA represents the numerical aperture of the microscope objective lens.

Abstract: A microscopic illumination apparatus to be applied to a microscope selectively using plural types of objective lenses having different magnifications comprises a light source, a collector lens for making a light flux emitted from the light source a substantially parallel light flux, and at least two fly-eye lenses disposed side by side along the optical axis at the back of the collector lens. A space between the two fly-eye lenses is variable in accordance with an objective lens to be used in the microscope.

Abstract: An illumination apparatus, having a light source that supplies illumination light, a collector lens that converts a divergent light flux emitted from the light source into a plurality of substantially parallel light fluxes, a fly-eye lens, comprised of a plurality of small lens elements and an exit surface, disposed at a rear focal position of the collector lens and a relay optical system that relays a pseudo plane light source which is formed on the exit surface of the fly-eye lens to an aperture stop or a surface conjugate to the aperture stop, where a focal length of at least one of the plurality of small lens elements is 8≦focal length ≦24, a radius of at least one of the plurality of small lens elements is 1≦radius ≦3 and a consistent unit of length is used for the focal length and radius.

Abstract: A microscopic illumination apparatus, comprises a light source for supplying illumination light, a collector lens for converting a divergent light flux emitted from the light source into substantially parallel light fluxes, a fly-eye lens disposed at a rear focal position of said collector lens, and a relay optical system for relaying a pseudo plane light source which is formed on an exit end surface of the fly-eye lens to an aperture stop or a surface conjugate to the aperture stop.

Abstract: Disclosed is a dark field illumination apparatus which is capable of performing a dark field illumination which exhibits a sufficient brightness and a sufficiently suppressed unevenness in brightness. The apparatus comprises a shaping system for shaping a light beam from a light source into approximately parallel beam having a ring- shaped section; a fly-eye optical device for forming a plurality of light source images in the vicinity of its exit plane based on the approximately parallel beam, the light source images being arranged circularly; and a light collection optical system for collecting light beams from the light source images and superposing them on an object plane.