Abstract: Provided is a projection optical system for forming an image of a pattern of a first object (R) on a second object (W). The projection optical system is made of an optical material having a refractive index of not more than 1.6 and is substantially telecentric both on the first object side and on the second object side. The projection optical system satisfies the condition of (?×L)/(NA×Y02)<1.5×10?3, where ? is a wavelength of light, L a distance between the first object and the second object, MA a numerical aperture on the second object side, and Y0 a maximum image height on the second object.

Abstract: Provided is a projection optical system for forming an image of a pattern of a first object (R) on a second object (W). The projection optical system is made of an optical material having a refractive index of not more than 1.6 and is substantially telecentric both on the first object side and on the second object side. The projection optical system satisfies the condition of (&lgr;×L)/(NA×Y02)<1.5×10−3, where &lgr; is a wavelength of light, L a distance between the first object and the second object, MA a numerical aperture on the second object side, and Y0 a maximum image height on the second object.

Abstract: Catadioptric systems are disclosed for projecting images of an object such as a mask onto a substrate. The catadioptric systems have high numerical apertures and large working distances. The catadioptric systems are useful with short-wavelength illumination and permit the object and substrate to be in parallel planes. Conditional expressions are provided for the catadioptric systems.

Abstract: A catadioptric reduction projection optical system having a structure capable of increasing a numerical aperture without increasing the size of a beam splitter and achieves excellent performance of a semiconductor manufacturing apparatus. The catadioptric reduction projection optical system comprises a first partial optical system having a first lens group, the beam splitter, a lens element, and a concave reflecting mirror to form an intermediate image of a first object, a second partial optical system for forming a reduced image of the intermediate image on a second object, the second partial optical system having a second lens group of a positive refracting power and arranged in an optical path between a second object surface and a surface on which the intermediate image is formed, and a third lens group arranged in an optical path between the beam splitter and the third lens group. The first lens group is arranged in an optical path between the first object and the beam splitter.

Abstract: A first partial optical system including a first group of lenses having a positive refractive power, a first concave reflection mirror and a second group of lenses having a positive refractive power, for forming a primary reduced image of an object, a second partial optical system including a second concave reelection mirror and a third group of lenses having a positive refractive power, for further reducing the primary reduced image and refocusing it, and a reflection mirror arranged between the first partial optical system and the second partial optical system, for deflecting a light path are arranged in a sequence as viewed from the object. A good image-forming ability as a projection optical system for fabricating a semiconductor device is attained with a simple construction.

Abstract: A catadioptric optical system includes, in succession from the object side, a first partial optical system having positive refractive power and for forming the primary image of an object, and a second partial optical system having positive refractive power and for forming a secondary image by light from the primary image, and at least one aperture stop may be provided in the optical path of the first partial optical system and at least one aperture stop may be provided in the optical path of the second partial optical system.

Abstract: An inverse telescopic wide angle lens comprises a diaphragm; a front lens group of an integral positive or negative refractive power, positioned in the object side in front of the diaphragm and having a first lens group of a negative refractive power including a negative lens of which an image-side air-contacting surface is formed as an aspherical surface concave to the image side, and a second lens group of a positive refractive power positioned between the first lens group and the diaphragm; and a rear lens group of an integral positive refractive power, positioned behind the diaphragm and having plural lenses.

Abstract: An optical position detecting apparatus detects a position level and inclination of a surface of an object to be detected without the need to increase the working distance of an objective optical system. The apparatus includes an objective optical system having a lens arranged to face the surface, an illuminating optical system for supplying a position detecting light beam from the periphery of the objective optical system, a photodetector for generating an electric output corresponding to a light beam received, a condenser optical system for converging a reflected light beam from the surface illumunated with the incident light beam from the illuminating optical system onto a photosensing surface of the photodetector, and a beam directing optical element for directing at least one of the incident light beam and the reflected light beam into an optical path passing through the lens.

Abstract: An inverse telescopic wide angle lens comprising:a diaphragm;a front lens group of an integral positive or negative refractive power, positioned in the object side in front of the diaphragm and having a first lens group of a negative refractive power including a negative lens of which an image-side air-contacting surface is formed as an aspherical surface concave to the image side, and a second lens group of a positive refractive power positioned between the first lens group and the diaphragm; anda rear lens group of an integral positive refractive power, positioned behind the diaphragm and having plural lenses;wherein the rear lens group includes a movable lens group consisting of plural lenses which are integrally moved for focusing, wherein the front lens group is fixed, and the focusing is conducted by the movement of the movable lens group alone in such a manner as to vary the rear focal length between the movable lens group and the image plane.

Abstract: In a zoom lens having a lens unit of negative refractive power most adjacent to the object side, distortion can be corrected better and an excellent imaging performance is maintained. In a zoom lens having a lens unit of negative refractive power most adjacent to the object side, a negative lens whose image side surface in contact with air is formed by a concave surface is provided in the lens unit of negative refractive power, and the shape of the concave surface of the negative lens is made into an aspherical surface which satisfies the condition that -5<.kappa.<0.75 with regard to a cone constant .kappa. and of which the curvature monotonically decreases away from the optical axis.