Abstract: A projection reflection optical system has two mirrors in a coaxial, four reflection configuration to reproduce the image of an object. The mirrors have spherical reflection surfaces to provide a very high resolution of object feature wavelengths less than 200 .mu.m, and preferably less than 100 .mu.m. An image resolution of features less than 0.05-0.1 .mu.m, is obtained over a large area field; i.e., 25.4 mm .times.25.4 mm, with a distortion less than 0.1 of the resolution over the image field.

Abstract: A lens system having discrete variations of focal length at discrete distances of radius outward from the optic axis for focussing light of plural wavelengths. The lens system which directs a laser beam onto a target for ablation or exposure applications includes one set of lens elements to handle short wavelength light used for ablation or exposure applications, and another set of lens elements to handle long wavelength light used for alignment applications. The lens system which provides for the ablation or exposure functions at short wavelength and for through-the-lens alignment at a longer wavelength and higher numerical aperture consists of three elements. Two outer lens elements are made entirely of fused quartz. An inner element disposed between the two outer lens is composed of any material such as optical glass. The inner lens element has a hole ground through its center.

Abstract: An optical coupling fluid which is transmissive to light, is a polymerized (cured) gel prepared from a mixture of two silicon components, one a silicon oil and one a silicon gel. The miscible substances can be combined to provide a composition suitable for preparation of a thin film between the optical components which then polymerizes to form the gel without danger of leakage. The transmissive characteristics are excellent, and coupling material does not become opaque to short wavelengths under use conditions.

Abstract: An improved welding mask glass to prevent orange flare is provided by utilizing as the glass in the lens a narrow bandpass green glass sold under Model S-8008N from Schott Glass Technologies, Inc., of Duryea, Pennsylvania. The transmission characteristic of the glass is a sharp cutoff from a peak of 544 nanometers toward the infrared which rejects objectionable "orange flares.

Abstract: A high-efficiency, diffractive optical element having at least one surface including multilevel steps, the steps determined by calculating equiphase boundaries utilizing a disclosed equation and algorithm. The optical element can be adapted to correct for chromatic and/or spherical aberration, and can be used in UV lithographic apparatus.

Abstract: An objective lens system for use within a microscope includes a first to a fourth lenses which are spaced apart from an object side. The first lens is made of either quartz or fluorite, the second and the third lenses are made of quartz, while the fourth lens is made of fluorite. The system transmits ultraviolet and/or far ultraviolet light and correct chromatic aberration. The system is uncomplicated.

Abstract: The present invention relates to an improved collimator assembly that includes two separate optical paths. Each optical path passes through a corrector lens arrangement substantially centered and aligned with one of two eyepiece lens assemblies. Each corrector lens arrangement is constructed so as to selectively refract light passing through it, in such a manner so as to counteract and reduce the axial chromatic aberrations that occur in the eyepiece lens assemblies.

Abstract: An objective lens system for use within a microscope includes six lenses which are spaced apart from an object side. The first, the third and the fifth lenses are made of quartz, the fourth and the sixth lenses are made of fluorite, while the second lens is made of either quartz or fluorite. The system transmits ultraviolet and/or far ultraviolet light is simply constructed and corrects chromatic aberration.

Abstract: An objective lens system for the rays within the ultraviolet region comprising, in the order from the object side, a first lens unit which has a positive refractive power, and comprises a meniscus lens component having a strongly concave surface on the object side and at least two cemented lens components, and a second lens unit which has a positive refractive power and comprises at least two cemented lens components, all the lens elements composing said objective lens system being made of optical materials having, when they are 5 mm thick, internal transmittance of at least 50% for a ray having a wavelength of 300 nm.

Abstract: An objective lens system for a microscope. The objective lens system includes a first lens group which includes a lens in the form of meniscus made of quartz or fluorite having a positive power; and a second lens group including a biconcave lens made of quartz and a biconvex lens made of fluorite. The first lens group and the biconcave and biconvex lenses are successively spaced apart from the object side of the system. The system transmits ultraviolet and/or far ultraviolet rays and can correct chromatic aberration. The system is uncomplicated.

Abstract: The present invention is directed to a medium incorporating melanin for radiation protection.

Abstract: A cemented lens comprising a first component having a polished first surface, a second component whose refractive index is different from that of the first component and having a second surface smoothed to a finish roughness of mesh #1400 or more but not polished, and an adhesive agent layer intervening between the first and second components to cement them at the first and second surfaces and having a refractive index which does not differ from that of the second component by more than 0.1.

Abstract: An optical system having a substantially flat image field is disclosed. The optical system is formed from optical subsystems wherein an input optical subsystem forms an intermediate image has a curvature which compensates that from the remaining optical components of the system to result in a substantially flat image for the optical system. Preferably the optical elements preceding the intermediate image and the optical elements succeeding the intermediate image are separately corrected for odd aberrations. The optical elements preceding the intermediate image and the optical elements succeeding the intermediate image compensate for each other and result in a substantially aberration free flat image for the optical system. The optical system preferably contains an input optical subsystem and an output optical subsystem wherein the input optical subsystem is a catadioptric system and wherein the output optical system is a dioptric system.