The present invention enables provision of a mirror unit in which a mirror is strongly adhered to a holder. A mirror unit according to one embodiment of the present invention is provided with: a mirror that comprises a mirror surface for reflecting light; and a holder that holds the mirror in a state of being adhered to the mirror, wherein adhesion surfaces of the holder to be adhered to the mirror 1 have uneven grooves. Since this configuration increases the surface area of the adhesion surfaces, the holder can be firmly adhered to the mirror, and thereby the risk of the mirror failing off the holder is decreased.

A flexure mount is described herein. The flexure mount includes three different flexures laterally offset from one another along a length of the flexure mount. The flexured design of the flexure mount allows for compliance in certain directions to reduce stress buildup normally associated with rigid mounting of dissimilar materials under dynamic thermal environments.

An optical mount includes a mount material in a closed geometry with an outer surface sized for matching internal dimensions of an outer housing, and an inner surface including spaced apart inward extending contacting features providing contact points that collectively define an inner opening sized for securing an optical device including a crystal within. At least one feature gap or a recessed portion is between the inward extending contacting features. Edge holders are adapted for receiving corners of the optical device can be the protrusion pair or inner notches. The outer surface includes at least one outer notch between the inward extending contacting features. The edge holders and outer notch(es) are for each acting as hinge points opening or pinching depending on a direction of force on the optical mount for responding with flexure when there is a dimensional change in the crystal, mount material, or the housing.

An improved mount for, and method of mounting an, optical structure is provided. The mount has an optical structure comprising at least one mirror panel, the mirror panel comprising a reflective surface and a back surface substantially opposite the reflective surface, a protruding member extending from the back surface of the optical structure, the protruding member having a shape and the shape having an outside surface there-around, a base comprising a mounting element and an upper element extending from the mounting element, the upper element having a cavity for secured receipt therein of at least a portion of the protruding member, wherein the receiving cavity of the upper element has a shape identical to that of the shape of the protruding member, but where the shape of the protruding member is ten thousandths ( 1/10,000) of an inch smaller than the shape of the receiving cavity so that the outside surface of the protruding member is ten thousandths ( 1/10,000) of an inch away from the corresponding parts of the receiving cavity when the protruding member is secured within the cavity.

In order to reduce the degree of relaxation after an optical substrate has been compacted, in particular after a longer period, substrates (51) or reflective optical elements (50), in particular for EUV lithography, with substrates (51) of this type, are proposed. These substrates (51), which have a surface region (511) with a reflective coating (54), are characterised in that, at least near to the surface region (511), the titanium-doped quartz glass has a proportion of SiOOSi bonds of at least 1*10.sup.16/cm.sup.3 and/or a proportion of SiSi bonds of at least 1*10.sup.16/cm.sup.3 or, along a notional line (513) perpendicular to the surface region (511), over a length (517) of 500 nm or more, a hydrogen content of more than 5?10.sup.18 molecules/cm.sup.3.

A connection arrangement for connecting a first component and a second component of an imaging device for micro lithography, such as for using light in the extreme UV range (EUV), includes a connection unit having a first contact portion, a second contact portion and a coupling portion.

A mirror assembly (32) for directing a beam (28) includes a base (450), and an optical element (454) that includes (i) a mirror (460), (ii) a stage (462) that retains the mirror (460), (iii) a mover assembly (464) that moves the stage (462) and the mirror (460) relative to the base (450), and (v) a thermally conductive medium (466) that is positioned between the stage (462) and the base (450) to transfer heat between the stage (462) and the base (450). The thermally conductive medium (466) has a thermal conductivity that is greater than the thermal conductivity of air. The thermally conductive medium (466) can include an ionic fluid or a liquid metal.

An all-reflective coronagraph optical system for continuously imaging a wide field of view. The optical system can comprise a fore-optics assembly comprising a plurality of mirrors that reflect light rays, about a wide field of view centered around the Sun, to an aft-optics assembly that reflects the light rays to an image sensor. A fold mirror, having an aperture, is optically supported between the fore-optics assembly and the aft-optics assembly. The aperture defines an angular subtense (e.g., 1.0 degree) sized larger than the angular subtense of the Sun. The aperture facilitates passage of a direct solar image and a solar thermal load. A thermal control subsystem comprises a shroud radiatively coupled to each fore-optics mirror and the fold mirror. A cold radiator is thermally coupled to each shroud. Heaters adjacent fore optics mirrors and the fold mirror control temperature to provide a steady state optical system to minimize wavefront error.

A mirror system is disclosed. The mirror system can include a primary mirror, and a secondary mirror supported relative to the primary mirror. The primary mirror and the secondary mirror can have different coefficients of thermal expansion (CTE). A negative CTE strut is also disclosed. The negative CTE strut can include a main body portion. The negative CTE strut can also include a first coupling portion and a second coupling portion disposed opposite one another about the main body portion and defining a strut length. The first and second coupling portions can each be configured to interface with an external structure. In addition, the negative CTE strut can include an offsetting extension member having a first end coupled to the main body portion and a second end coupled to the first coupling portion by an intermediate extension member. The first end can be between the first coupling portion and the second end. The first and second ends can define an offset length parallel to the strut length. When the negative CTE strut increases in temperature, the offset length can be configured to increase due to thermal expansion of the offsetting extension member sufficient to cause the strut length to decrease.

An optical apparatus is disclosed, the apparatus comprising an optical element having a reflective surface for reflecting incident radiation in a beam path, and at least one sensor configured to sense radiation corresponding to a temperature of a respective portion of a backside surface of the optical element. Also disclosed is a method of controlling a temperature of a reflective surface of an optical element in a lithographic apparatus.