A refractive projection lens for imaging a pattern in an object plane of the projection lens into an image plane of the projection lens via electromagnetic radiation of a mercury vapor lamp includes a multiplicity of lens elements are arranged along an optical axis between the object and image planes. The lens elements image a pattern in the object plane into the image plane with a reducing imaging scale. The lens elements include first lens elements made of a first material with a relatively low Abbe number and a second lens elements made of a second material with a higher Abbe number relative to the first material.

An imaging optical unit for projection lithography has a plurality of mirrors for imaging an object field into an image field with imaging light guided along a path from the object field to the image field. The penultimate mirror in the path has no passage opening to pass the imaging light. The imaging optical unit has a stop to predefine an outer marginal contour of a pupil of the imaging optical unit. The stop is between the penultimate and last mirrors in the path. The imaging optical unit can have exactly one stop for predefining at least one section of the outer pupil marginal contour. An entrance pupil of the imaging optical unit can be upstream of the object field. The imaging optical unit can be well defined regarding its pupil and exhibit desirable properties for projection lithography.

In a method for designing a mirror when any point on a reflecting surface is represented by M, coordinates of an intersection point between a sagittal light source ray and an incoming light ray to the M point and an intersection point between a meridional light source ray and the incoming light ray to the M point are expressed by using L.sub.1s and L.sub.1m, and coordinates of an intersection point between an outgoing light ray from the M point and a sagittal collected light ray and an intersection point between the outgoing light ray from the M point and a meridional collected light ray are expressed by using L.sub.2s and L.sub.2m. A mirror is designed using design formulas of a reflecting surface derived based on the coordinates and a condition that an optical path length from a light source position to a light collection position is constant with respect to any point on the reflecting surface for both the light collection in the sagittal direction and the light collection in the meridional direction.

An optical lens system includes, in order from a magnified side to a minified side, a first lens group of positive refractive power and a second lens group of positive refractive power. The first lens group includes a first lens and a second lens, and the second lens group includes a third lens and a fourth lens. One of the third lens and the fourth lens includes one aspheric surface, and each of the lenses in the optical lens system is a singlet lens. The optical lens satisfies a condition of TE.sub.(=400)>94%, where TE.sub.(=400) denotes an overall transmittance of all of the lenses in the optical lens system measured at a wavelength of 400 nm.

An optical assembly and a method for making the optical assembly. The optical assembly includes an optical element; a blocking coating; a capping layer on the blocking coating; a holder; and an adhesive configured to adhere the optical element to the holder. The blocking coating includes a light absorber that does not transmit light with wavelengths from greater than or equal to about 250 nm to less than or equal to about 400 nm; The light absorber is positioned such that light having a wavelength from greater than or equal to about 190 nm to less than or equal to about 500 nm is not incident to the adhesive. The capping layer is made from a material having high transmission in the UV and enables use of aggressive cleaning treatments on the optical element significant impairment of the UV transmission of the optical element.

A method for loading a blank composed of fused silica with hydrogen, including loading the blank at a first temperature (T.sub.1) and a first hydrogen partial pressure (p.sub.1), and further loading the blank at a second temperature (T.sub.2) which is different from the first temperature and at a second hydrogen partial pressure (p.sub.2) which is different from the first hydrogen partial pressure. The first and second temperatures (T.sub.1, T.sub.2) are lower than a limit temperature (T.sub.L) at which a thermal formation of silane in the fused silica of the blank commences. Also disclosed are a lens element produced from such a blank and a projection lens that includes at least one such lens element.

A multilayer mirror for reflecting Extreme Ultraviolet (EUV) radiation and a method for producing the same are disclosed. In an embodiment a multilayer mirror includes a layer sequence having a plurality of alternating first layers and second layers, the first layers including lanthanum or a lanthanum compound and the second layers including boron, wherein the second layers are doped with carbon, and wherein a molar fraction of carbon in the second layers is 10% or less.

Disclosed are methods and apparatus for reflecting, towards a sensor, an Infrared to vacuum ultra-violet (VUV) light that is reflected from a target substrate. The system includes a first mirror arranged to receive and reflect the Infrared to VUV light that is reflected from the target substrate and a second mirror arranged to receive and reflect Infrared to VUV light that is reflected by the first mirror. The first and second mirrors are arranged and shaped so as to reflect Infrared to VUV light from the target substrate towards an optical axis of the apparatus. In another embodiment, the apparatus can also include a third mirror arranged to receive and reflect the Infrared to VUV light that is reflected by the second mirror and a fourth mirror arranged to receive and reflect such illuminating light that is reflected by the third mirror towards the sensor. In one more embodiment, a reflecting or refracting optics is used to relay the image by above optics to the sensor; various magnification is achieved by adjusting the distance between the intermediate image and the relay optics.

A lens system includes a curved primary mirror and an aspheric secondary mirror. The aspheric secondary mirror has a diameter smaller than that of the primary mirror and shares an optical axis with the primary mirror. The aspheric secondary mirror and the primary mirror are rotationally symmetric with respect to the optical axis. A support member, which may be transparent over an operating wavelength of the lens system, is disposed on the aspheric secondary mirror.

A catadioptric projection objective for images an object field onto an image field via imaging radiation. The projection objective includes at least one reflective optical component and a measuring device. The reflective optical component, during the operation of the projection objective, reflects a first part of the imaging radiation and transmits a second part of the imaging radiation. The reflected, first part of the imaging radiation at least partly contributes to the imaging of the object field. The transmitted, second part of the imaging radiation is at least partly fed to a measuring device. This allows a simultaneous exposure of the photosensitive layer at the location of the image field with the imaging radiation and monitoring of the imaging radiation with the aid of the measuring device.