US 6,894,834 B2 · Objective with pupil obscuration

Abstract

An objective is configured with a first partial objective and a second partial objective. The first partial objective, which projects a first field plane onto an intermediate image, has a first, convex mirror and a second, concave mirror. The second partial objective, which projects the intermediate image onto a second field plane, has a third and a fourth mirror, both concave. All of the four mirrors have central mirror apertures. The axial distance between the first and second mirrors is in a ratio between 0.95 and 1.05 relative to the distance between the second mirror and the intermediate image. The axial distance ZM3-IM between the third mirror and the second field plane conforms to the relationship 0.03 · Du M3 + 5.0 ⁢ ⁢ mm < Z M3 - IM < 0.25 · Du M3 tan ⁡ ( arcsin ⁡ ( NA ) ) . NA represents the numerical aperture NA in the second field plane, and DuM3 represents the diameter of the third mirror. The objective furthermore has a Petzval radius with an absolute value larger than the distance between the first and second field planes.

Claims47

Dependent claims

An objective having a first field plane, an intermediate image plane, and a second field plane, the objective comprising

a first partial objective having a first, convex mirror with a first central mirror aperture and a second, concave mirror with a second central mirror aperture;
and
a second partial objective having a third, concave mirror with a third central mirror aperture and a fourth, concave mirror with a fourth central mirror aperture;
wherein the first field plane and the intermediate image plane are conjugate planes relative to the first partial objective, and the intermediate image plane and the second field plane are conjugate planes relative to the second partial objective,
wherein the first mirror has a first axial distance from the second mirror, the second mirror has a second axial distance from the intermediate image, and said first and second axial distances have a ratio between 0.95 and 1.05 relative to each other;
wherein the third mirror has a third axial distance ZM3-IM from the second field plane, and said third axial distance conforms to the relationship
0.03
·
Du
M3
+
5.0
⁢
⁢
mm
<
Z
M3
-
IM
<
0.25
·
Du
M3
tan
⁡
(
arcsin
⁡
(
NA
)
)
,
NA representing a numerical aperture NA in the second field plane, and DuM3 representing a diameter of the third mirror;
and wherein further the second field plane has a fourth axial distance from the first field plane, and the objective has a Petzval radius whose absolute value is greater than said fourth axial distance.

34 more elements

Dependencies are inferred from the claim text.

Objective with pupil obscuration

Life of this patent

Objective with pupil obscuration

Life of this patent

Abstract

Claims47