Broad spectrum ultraviolet catadioptric imaging system

Claim 2

A broad-band deep-ultraviolet achromatic catadioptric imaging system, comprising: a focusing lens group including a plurality of lens elements, all formed from a single refractive material with refractive surfaces thereof disposed at first predetermined positions along an optical path of the system and having curvatures and said positions selected to focus ultraviolet light at an intermediate image within the system, and simultaneously to also provide in combination with the rest of the system, high levels of correction of both image aberrations and chromatic variation of aberrations over a wavelength band including at least 0.20-0.29 μm, a field lens group with a net positive power disposed along said optical path proximate to said intermediate image, the field lens group including a plurality of lens elements formed from at least two different refractive materials with different dispersions, with refractive surfaces of the lens elements of the field lens group disposed at second predetermined positions and having curvatures selected to provide correction of chromatic aberrations including at least secondary lateral color of the system over said wavelength band, a catadioptric group including a first optical element having at least a concave reflective surface with a central optical aperture therein disposed along said optical path proximate to said intermediate image so that ultraviolet light from the intermediate image can pass therethrough, the catadioptric group also including a second optical element which is a lens with a reflective mirror coating on a rear surface of said lens except for a central area on said rear surface where said mirror coating is absent, the optical elements of said catadioptric group being arranged such that ultraviolet light from the intermediate image transmitted through said central optical aperture of said first optical element of said catadioptric group passes through the lens portion of said second optical element of said catadioptric group, reflects from said reflective mirror coating on said lens rear surface, passes back through said lens portion towards said concave reflective surface of said first optical element, is reflected thereby and passes a third time through said lens portion of said second optical element and through said central area of said lens rear surface to form a final image beyond said catadioptric group.

Claim 3

The imaging system of claim 1 wherein said wavelength band includes 0.20-0.40 μm.

Claim 4

The imaging system of claim 1 wherein said wavelength band includes 0.193 μm.

Claim 5

The imaging system of claim 1 wherein said single refractive material type of said focusing lens group is fused silica.

Claim 6

The imaging system of claim 1 wherein said field lens group is formed from lens elements made of fused silica and a fluoride glass.

Claim 7

The imaging system of claim 1 wherein said first optical element of said catadioptric group comprises a concave mirror with a central hole therein forming said central optical aperture.

Claim 8

The imaging system of claim 1 wherein said first optical element of said catadioptric group comprises a meniscus lens with a concave reflective surface coating thereon.

Claim 9

The imaging system of claim 7 wherein said central optical aperture is formed by a central hole in said meniscus lens.

Claim 10

The imaging system of claim 7 wherein said central optical aperture is formed by a central area on said meniscus lens where said concave reflective surface coating is absent.

Claim 11

The imaging system of claim 1 wherein said catadioptric group is characterized by reflective surface curvatures selected to provide at least a 0.8 numerical aperture and a 0.5 mm field of view for said final image of the imaging system.

Claim 12

A broad-band deep-ultraviolet achromatic catadioptric imaging system, comprising: a first negative lens, a second positive biconvex lens closely spaced to the first lens to form a substantially zero-power corrector group for chromatic variations of image aberrations, a third negative meniscus lens spaced from the second lens, a fourth negative meniscus lens with concave surfaces of the third and fourth lenses facing each other, a fifth positive biconvex lens, a sixth positive meniscus lens, a seventh meniscus lens of near zero-power with concave surfaces of the sixth and seventh lenses facing each other, the third through seventh lenses being closely spaced together to form a focusing lens group with minimal image aberrations over a specified wavelength band that includes at least 0.22-0.29 μm ultraviolet wavelengths, said focusing lens group providing an intermediate image, eighth, ninth and tenth lenses forming a field lens group positioned proximate to said intermediate image, said field lens group being substantially achromatic over said specified wavelength band, said field lens group including at least one positive convex lens of a different refractive material type than all other lenses in the system and at least one negative meniscus lens, the field lens group having a net positive power, an eleventh negative meniscus lens with a convex surface facing said first lens having a reflective coating thereon and with a first central optical aperture therein proximate to said intermediate image, and a twelfth near zero-power, substantially flat lens with a reflective coating on a surface facing away from the first lens with a second central optical aperture therein, said twelfth lens spaced apart from the eleventh lens, the eleventh and twelfth lenses with their respective reflective coatings forming a catadioptric group providing a light focusing relay for the intermediate image to provide a final image proximate to the second optical aperture for which chromatic aberrations are substantially corrected in said final image over said specified wavelength band.

Claim 13

A broad-band deep-ultraviolet achromatic catadioptric imaging system, comprising: a first negative lens, a second positive biconvex lens closely spaced to the first lens to form a substantially zero-power corrector group for chromatic variations of image aberrations, a third negative meniscus lens spaced from the second lens, a fourth negative meniscus lens with concave surfaces of the third and fourth lenses facing each other, a fifth positive biconvex lens, a sixth positive meniscus lens, a seventh meniscus lens of near zero-power with concave surfaces of the sixth and seventh lenses facing each other, the third through seventh lenses being closely spaced together to form a focusing lens group with minimal image aberrations over a specified wavelength band that includes at least 0.22-0.29 μm ultraviolet wavelengths, said focusing lens group providing an intermediate image, eighth, ninth and tenth lenses forming a field lens group positioned proximate to said intermediate image, said field lens group being substantially achromatic over said specified wavelength band, said field lens group including at least one positive convex lens of a different refractive material type than all other lenses in the system and at least one negative meniscus lens, the field lens group having a net positive power, an eleventh negative meniscus lens with a convex surface facing said first lens having a reflective coating thereon and with a first central optical aperture therein proximate to said intermediate image, and a twelfth near zero-power, substantially flat lens with a reflective coating on a surface facing away from the first lens with a second central optical aperture therein, said twelfth lens spaced apart from the eleventh lens, the eleventh and twelfth lenses with their respective reflective coatings forming a catadioptric group providing a light focusing relay for the intermediate image to provide a final image proximate to the second optical aperture for which chromatic aberrations are substantially corrected in said final image over said specified wavelength band.

Claim 14

The imaging system of claim 11 wherein the third lens is spaced at least 30 mm from the second lens, and said twelfth lens is spaced at least 30 mm from the eleventh lens.

Claim 15

The imaging system of claim 11 wherein the focusing lens group, field lens group and catadioptric group have refractive and reflective surfaces that are characterized by the following dimensional values: ______________________________________ Radius of Surface # Curvature (mm) Spacing (mm) Material ______________________________________ 1 1105.7 4.000 fused silica 2 53.051 2.500 air 3 284.061 5.000 fused silica 4 -57.181 60.000 air 5 39.782 15.000 fused silica 6 13.379 7.977 air 7 -12.955 5.169 fused silica 8 -17.192 1.000 air 9 42.964 8.000 fused silica 10 -55.269 1.000 air 11 18.436 8.000 fused silica 12 91.574 6.253 air 13 -20.802 4.000 fused silica 14 -21.768 17.120 air 15 7.217 5.494 fused silica 16 2.259 3.000 CaF.sub.2 glass 17 -11.760 1.500 fused silica 18 373.721 39.730 air 19 flat 7.000 fused silica 20 flat -7.000 reflector/ fused silica 21 flat -36.000 air 22 50.470 -9.500 fused silica 23 64.290 9.500 reflector/ fused silica 24 50.470 36.000 air 25 flat 7.000 fused silica 26 flat 1.500 air ______________________________________

Claim 16

The imaging system of claim 11 wherein the focusing lens group, field lens group and catadioptric group have refractive and reflective surfaces that are characterized by the following dimensional values: ______________________________________ Radius of Surface # Curvature (mm) Spacing (mm) Material ______________________________________ 1 -67.007 4.000 fused silica 2 50.308 2.000 air 3 120.297 6.000 fused silica 4 -37.494 30.636 air 5 24.138 10.000 fused silica 6 13.441 9.532 air 7 -13.518 7.546 fused silica 8 -17.997 1.000 air 9 34.465 6.000 fused silica 10 -517.022 1.000 air 11 18.268 10.000 fused silica 12 965.352 4.181 air 13 -30.177 9.746 fused silica 14 -28.138 7.892 air 15 -19.346 2.500 fused silica 16 -36.530 1.000 air 17 6.687 5.026 fused silica 18 2.044 0.017 air 19 2.044 2.000 CaF.sub.2 glass 20 -90.635 36.108 air 21 -908.968 7.000 fused silica 22 -1000.0 -7.000 reflector/ fused silica 23 -908.968 -36.000 air 24 48.244 -9.500 fused silica 25 63.204 9.500 reflector/ fused silica 26 48.244 36.000 air 27 -908.968 7.000 fused silica 28 -1000.0 1.500 air ______________________________________

Claim 17

A broad-band deep-ultraviolet achromatic catadioptric imaging system, comprising: a focusing lens group including a plurality of lens elements, with refractive surfaces thereof disposed at first predetermined positions along an optical path of the system and having curvatures and said positions selected to focus ultraviolet light at an intermediate image within the system, and simultaneously to also provide in combination with the rest of the system, high levels of correction of both image aberrations and chromatic variation of aberrations over a wavelength band including at least 0.22-0.29 μm, a field lens group with a net positive power disposed along said optical path proximate to said intermediate image, the field lens group including a plurality of lens elements formed from at least two different refractive materials with different dispersions, with refractive surfaces of the lens elements of the field lens group disposed at second predetermined positions and having curvatures selected to provide substantial correction of chromatic aberrations including at least secondary longitudinal color and primary and secondary lateral color of the system over said wavelength band, a catadioptric relay group, including a combination of at least two reflective surfaces and at least one refractive surface disposed at third predetermined positions and having curvatures selected to form a real final image of said intermediate image such that, in combination with said focusing lens group, primary longitudinal color of the system is substantially corrected over said wavelength band.

Claim 18

A broad-band deep-ultraviolet achromatic catadioptric imaging system, comprising: a focusing lens group including a plurality of lens elements, with refractive surfaces thereof disposed at first predetermined positions along an optical path of the system and having curvatures and said positions selected to focus ultraviolet light at an intermediate image within the system, and simultaneously to also provide in combination with the rest of the system, high levels of correction of both image aberrations and chromatic variation of aberrations over a wavelength band including at least 0.22-0.29 μm, a field lens group with a net positive power disposed along said optical path proximate to said intermediate image, the field lens group including a plurality of lens elements formed from at least two different refractive materials with different dispersions, with refractive surfaces of the lens elements of the field lens group disposed at second predetermined positions and having curvatures selected to provide substantial correction of chromatic aberrations including at least secondary longitudinal color and primary and secondary lateral color of the system over said wavelength band, a catadioptric relay group, including a combination of at least two reflective surfaces and at least one refractive surface disposed at third predetermined positions and having curvatures selected to form a real final image of said intermediate image such that, in combination with said focusing lens group, primary longitudinal color of the system is substantially corrected over said wavelength band.

Claim 19

The imaging system of claim 15 wherein all of said lens elements of said focusing lens group are formed from a single refractive material type.

Claim 20

The imaging system of claim 16 wherein said single refractive material type of said focusing lens group is silica.

Claim 21

The imaging system of claim 15 wherein said catadioptric relay group includes a first reflective optical element with a concave reflective surface, said concave reflective surface having a central optical aperture therein disposed along said optical path proximate to said intermediate image so that ultraviolet light from the intermediate image can pass therethrough, said catadioptric relay group also including a second optical element which is a lens with a reflective mirror coating on a rear surface of said lens except for a central area on said rear surface where said mirror coating is absent, said concave reflective surface of said first reflective optical element and said reflective mirror coating of said second optical element forming said at least two reflective surfaces of said catadioptric relay group, a front surface of said lens of said second optical element forming said at least one refractive surface of said catadioptric relay group, said optical elements of said catadioptric relay group being arranged such that ultraviolet light from the intermediate image transmitted through said central optical aperture in said concave reflective surface of said first reflector optical element passes through the lens portion of said second optical element, reflects from said reflective mirror coating on said lens rear surface, passes back through said lens portion towards said first reflective optical element, is reflected by said concave reflective surface of said first reflective optical element, and passes a third time through said lens portion of said second optical element and through said central area of said lens rear surface where said reflective mirror coating is absent to form a final image beyond said catadioptric relay group.

Claim 22

The imaging system of claim 18 wherein said first reflective optical element of said catadioptric relay group comprises a concave mirror with a central hole therein forming said central optical aperture.

Claim 23

The imaging system of claim 15 wherein said at least two different refractive materials with different dispersions forming said lens elements of said field lens group includes both silica and a fluoride glass.