Abstract: An eccentrically oscillating type reduction gear includes an internal gear, an external gear which meshes with the internal gear, and an eccentric body which oscillates the external gear. The external gear is formed of a resin, and the internal gear has an internal gear main body which is formed of a resin, and an outer pin which is rotatably disposed in a pin groove provided in the internal gear main body and is formed of a material having a thermal conductivity higher than that of the resin constituting the internal gear main body.

Abstract: An eccentric oscillation type speed reducer includes: an internal gear; an external gear which meshes with the internal gear; an eccentric body shaft which oscillates the external gear; and a carrier disposed at a side portion of the external gear in an axial direction, in which the carrier includes a first carrier which is disposed on one side in the axial direction of the external gear, and a second carrier which is disposed on the other side in the axial direction of the external gear, a driven member is connected to the first carrier, the first carrier is made of metal, and the second carrier is made of resin.

Abstract: A double-focus detector utilizing a lens system having axial chromatic aberration vertically illuminates a mask and a wafer disposed at a minute interval in the direction of the optical axis of the lens system. The mask is illuminated with a single ray of wavelength 500 nm or more and the wafer is illuminated with a given band flux or a plurality of rays of wavelength larger than that selected for the mask and one of focus planes of the lens system is an image forming plane of the single ray and the other focus plane of the lens system is the same image forming plane of the given band ray or the plurality of rays so that the relative position between the mask and the wafer can be detected.

Abstract: A double-focus detector utilizing chromatic aberration has a lens system having axial chromatic aberration in which a first object such as a mask is illuminated with a ray of wavelength below 500 nm and a second object such as a wafer is illuminated with plural wavelength rays or a wavelength-band ray above 500 nm, by employing an image forming plane of the first object with respect to the single wavelength ray as one focal plane of the lens system and the same image forming plane of the second object with respect to the plural wavelength rays or the wavelength-band ray as the other focal plane of the lens system.

Abstract: A position detector for use with an X ray exposure apparatus and the like includes sector Fresnel zone plates (SFZP) which are provided on a mask and a wafer minutely spaced in position in the direction of the optical axis of an exposure X ray, as alignment marks. A laser ray of at least one of wavelength is applied to the surfaces of the SFZPs at an angle with respect to the surfaces. The SFZPs are designed such that the principal focal planes of Fesnel diffraction images of the SFZPs to a single wavelenth laser ray agree with each other. In the case of illumination rays of a plurality of wavelengths, an objective lens is provided in a detection optical system which objective has such an axial chromatic aberration that focal planes of the objective lens to the plural wavelength rays agree with respective Fresnel diffraction focal planes of the SFZPs to the rays.

Abstract: A double-focus detector utilizing chromatic aberration vertically illumates a mask and a wafer which are disposed at a minute interval in the direction of illumination rays, in the direction normal to the mask and the wafer through a band-pass filter or band-pass filters which transmit a single wavelength ray and a wavelength-band ray, both or respectively and an objective to produce axial chromatic aberration corresponding to the minute interval with respect to the single wavelength ray and the wavelength-band ray, and observes images of the mask and the wafer which are formed by the single wavelength and the wavelength-band ray reflected by the mask and the wafer, thereby detecting a relative position between the mask and the wafer in a direction perpendicular to the optical axis of the illumination rays.