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US 11,029,606 B2Granted
Optical element for the beam guidance of imaging light in projection lithography
AssigneeCarl Zeiss SMT GmbH
InventorsJens Prochnau, Dirk Schaffer, Roman Orlik
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Abstract
An optical element is configured to guide imaging light in projection lithography. The optical element has a main body and at least one optical surface carried by the main body. At least one compensation weight element, which is attached to the main body, serves for a weight compensation of a figure deformation of the optical surface caused by gravity. This results in an optical element with a small figure deformation at the use location.
Claims22
An optical element, comprising:
- a main body;
- an optical surface supported by the main body;
- a compensation weight element supported by the main body, the compensation weight element comprising a compensation weight;
- and
- a lever connecting the compensation weight to the main body in a connection region so that a direction of a gravitational force of the compensation weight, proceeding from a center of mass thereof, extends a distance from the connection region,
- wherein:
- the lever has an adjustable length, and/or the lever has an adjustable direction;
- and
- the compensation weight element is configured to compensate a figure deformation of the optical surface caused by gravity.
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A method, comprising:
- producing a blank of an optical element taking account of a negative deformation allowance so that the optical element has a desired figure only under a gravitational force of at least one compensation weight;
- transporting the blank to a use location of an apparatus for projection lithography;
- and
- attaching the at least one compensation weight element to a main body of the optical element taking account of a gravitational acceleration at the use location for weight compensation of a figure deformation of an optical surface of the optical element caused by gravity,
- wherein attaching the at least one compensation weight element to the main body of the optical element comprises:
- a) attaching at least one raw compensation weight element to the main body of the optical element, the at least one raw compensation weight element being designed to overcompensate an expected effect of gravity on the figure deformation of the optical surface of the optical element and
- b) after a), removing part of the at least one raw compensation weight element to reduce its weight to achieve a desired figure deformation of the optical surface of the optical element.
4 more elements
Dependencies are inferred from the claim text.