Abstract: An objective includes a first lens group that has a positive refractive power and a second lens group that has a negative refractive power. The objective satisfies conditional expressions below. 0.2?NAob?1??(1) 2.9 mm?D0×NAob?30 mm??(2) 30 mm?L?70 mm??(3) 0.0001?RMSh/?h?0.035??(4) NAob is a numerical aperture on an object side of the objective. D0 is a distance on an optical axis between an object plane and a lens surface of the objective that is situated closest to the object side. L is a distance on the optical axis between the object plane and a lens surface of the objective that is situated closest to the image side. RMSh is an axial RMS wave aberration with respect to the h line. ?h is a wavelength of the h line.

Abstract: When the half rings are opened, the position of the opened half rings is not stable and therefore it was difficult to insert or remove the loose leaf or leaves.

Abstract: An area-light source outputs uniform area light on a sample. A wedge diaphragm is placed between the area-light source and the sample. The wedge diaphragm has a notch. The wedge diaphragm is moved in a direction perpendicular to the optical axis of the area light so as to adjust an amount of the area light passing through the sample.

Abstract: An area-light source outputs uniform area light on a sample. A wedge diaphragm is placed between the area-light source and the sample. The wedge diaphragm has a notch. The wedge diaphragm is moved in a direction perpendicular to the optical axis of the area light so as to adjust an amount of the area light passing through the sample.