Abstract: A wide range within a subject eye is observed while a burden on a subject of whom the subject eye is part is moderated. In an optical system that deals with light reflected from the fundus of the subject eye, a first optical system that pertains to a field of view of a fundus central portion centered on an optical axis is used as a standard optical system. The optical system can be switched by a replacement mechanism from the first optical system to a second optical system that pertains to a field of view of a fundus surroundings portion surrounding the fundus central portion.

Abstract: Both observation of a wide range within a subject eye may be enabled and a burden on a subject of whom the subject eye is part may be moderated. In order of incidence of light from a side at which a pupil of the subject eye is disposed, spreading of the luminous flux is suppressed by a first refracting face, the light is reflected by a first reflection surface with a central aperture, directing the luminous flux in convergent directions in a direction toward the subject eye, the light is reflected in the direction opposite to the direction toward the subject eye by a second reflection surface, and the light is transmitted through the central aperture of the first reflection surface and forms a pupil conjugate image that is conjugate with a position of the pupil of the subject eye.

Abstract: A wide range within a subject eye is observed while a burden on a subject of whom the subject eye is part is moderated. In an optical system that deals with light reflected from the fundus of the subject eye, a first optical system that pertains to a field of view of a fundus central portion centered on an optical axis is used as a standard optical system. The optical system can be switched by a replacement mechanism from the first optical system to a second optical system that pertains to a field of view of a fundus surroundings portion surrounding the fundus central portion.

Abstract: Both observation of a wide range within a subject eye may be enabled and a burden on a subject of whom the subject eye is part may be moderated. In order of incidence of light from a side at which a pupil of the subject eye is disposed, spreading of the luminous flux is suppressed by a first refracting face, the light is reflected by a first reflection surface with a central aperture, directing the luminous flux in convergent directions in a direction toward the subject eye, the light is reflected in the direction opposite to the direction toward the subject eye by a second reflection surface, and the light is transmitted through the central aperture of the first reflection surface and forms a pupil conjugate image that is conjugate with a position of the pupil of the subject eye.

Abstract: According to one embodiment relates to an optical system radially downsized and corrected well for aberration and is applicable, for example, to an aberration measuring apparatus for measuring wavefront aberration of a liquid immersion projection optical system. A catadioptric system of a coaxial type is provided with a first optical system which forms a point optically conjugate with an intersecting point with the optical axis on a first plane intersecting with the optical axis, on a second plane, and a second optical system which guides light from the first optical system to a third plane. The first optical system has a first reflecting surface arranged at or near the first plane, a second reflecting surface having a form of an ellipsoid of revolution the two focuses of which are aligned along the optical axis in a state in which one focus is located at or near a first light transmissive portion, and a medium filling an optical path between the first reflecting surface and the second reflecting surface.

Abstract: An object is to provide a projection optical system, for example, capable of improving the throughput of scanning exposure in application to scanning exposure apparatus. A projection optical system for forming an image of a first surface and an image of a second surface on a third surface comprises a first imaging optical system, a second imaging optical system, a third imaging optical system, a fourth imaging optical system, a fifth imaging optical system, a sixth imaging optical system, a seventh imaging optical system, a first folding member disposed between the third imaging optical system and the seventh imaging optical system, and a second folding member disposed between the sixth imaging optical system and the seventh imaging optical system.

Abstract: A refractive projection optical system in which a large image side numerical aperture can be ensured by interposing liquid in the optical path to the image plane, and an image having good planarity can be formed while suppressing radial upsizing. The projection optical system comprising a first image forming system arranged in the optical path between a first plane (R) and a point optically conjugate to a point on the optical axis of the first plane, and a second image forming system arranged in the optical path between the conjugate point and a second plane. In the projection optical system, all optical elements having power are refractive optical elements. The optical path between the projection optical system and the second plane is fillable with liquid having a refractive index larger than 1.3.

Abstract: Flame-retardant polyester resin compositions are disclosed which have improved mechanical properties, particularly improved impact properties. The compositions comprise a halogen-containing copolymeric polyester resin derived from terephthalic acid or its derivative, an alkylene glycol or its derivative and a halogen-containing aromatic diol, said copolymeric polyester resin being blended with a minor amount of a modified ethylene copolymer derived by graft polymerization of an .alpha.,.beta.-unsaturated carboxylic acid or its derivative on the backbone of ethylene/.alpha.-olefin copolymer, and/or a minor amount of an acrylic rubber.

Abstract: A polyester resin composition comprising:(a) 100 parts by weight of a copolymerized polyester resina with a halogen content of 3 to 15% by weight prepared by copolymerizing terephthalic acid or an ester-forming derivative thereof; an alkylene glycol having 2 to 10 carbon atoms or an ester-forming derivative thereof; and a halogen-containing aromatic diol represented by the general formula: ##STR1## wherein R represents an alkylene of 2 to 4 carbon atoms, X represents a halogen atom, 1 and m each represents an integer of 1 to 4 and p and q each represents an integer of 1 to 10, and(b) 0.1 to 10 parts by weight of an acrylic resin b with a halogen content of not less than 10% by weight prepared by polymerizing a benzyl acrylate or benzyl methacrylate represented by the general formula: ##STR2## wherein Y represents a halogen atom, n represents, an integer of 1 to 5 and Z represents hydrogen or methyl.

Abstract: A polyamide based resin composition is prepared mixing a resin composition with a urea compound of the formula: R.sup.2 --NHCONH--R.sup.1 --NHCONH--R.sup.3 wherein R.sup.1 is an aromatic hydrocarbon group and R.sup.2 and R.sup.3 are both aliphatic groups of 8 to 32 carbon atoms, said resin composition being prepared by melt mixing 99 to 40 parts by weight of a polyamide resin and 1 to 60 parts by weight of a modified ethylene copolymer prepared by graft copolymerizing a copolymer of ethylene and an .alpha.-olefin of at least three carbon atoms with an .alpha.,.beta.-unsaturated carboxylic acid or derivative thereof.

Abstract: A polyamide resin composition comprises melamine cyanurate with or without a copper compound, an alkali metal halide, a tin compound, a bisamide compound or a bisureido compound.