Patent ID: 11899371
Assignee: NIKON CORPORATION
Field: nan (nan)
Classification: CPC nan | IPC G

Claim 14:
15. A catoptric system having a reference axis and operable to form an image of a pattern-source, the system comprising:
first, second, and third reflectors situated on the reference axis and a reflective element, situated on the reference axis between the second reflector and the third reflector, the first reflector including the pattern-source; and
a combination of the second and third reflectors configured to form the image with a reduction factor N>1, of a substantially one-dimensional (1D) diffractive structure of the pattern-source in extreme UV light provided by only two diffracted beams of light, in a plane that is optically-conjugate to the first reflector, wherein the only two diffracted beams of light originate at the first reflector as a result of irradiation of the first reflector with an illumination beam of light, and
wherein the only two diffracted beams of light do not include a beam of light that represents a specular reflection of the illumination beam of light at the first reflector,
the second reflector includes a convex reflector unit defining a first opening therein,
the third reflector includes a concave reflector unit defining a second opening therein,
the reflective element is situated to reflect the illumination beam of light to the pattern-source,
the system configured to:
receive, at a surface of the convex reflector unit, the two diffracted beams of light delivered thereto through the second opening defined in the third reflector,
receive, at the concave reflector unit, the two diffracted beams of light from the surface of the convex reflector unit and reflect the two diffracted beams of light through the first opening defined in the second reflector to form the image of the pattern-source at an image plane;
wherein the two diffracted beams of light are generated at the pattern-source in response to the irradiating with the illumination beam received from the reflective element, and wherein the reflective element is situated to block light from the pattern-source and passing between the two diffracted beams of radiation produced at the pattern-source.