An extreme ultraviolet light generation system according to one aspect of the present disclosure includes: a pulse laser apparatus configured to output a pulse laser beam, the pulse laser beam being supplied to a predetermined region in a chamber in which plasma containing extreme ultraviolet light is to be generated; a sensor configured to detect a beam size of the pulse laser beam; an actuator configured to change the beam size; and a controller. The controller performs, based on a first algorithm, first control that controls the actuator by a first control amount in a beam size minifying direction when the beam size has exceeded a first upper limit threshold in one burst duration, and then performs, based on a second algorithm, second control that controls the actuator by a second control amount smaller than the first control amount so that the beam size becomes closer to a target value.

A freeform surface optical telescope imaging system is provided. The freeform surface optical telescope imaging system comprises a primary mirror, a secondary mirror, a compensating minor, and a spherical mirror. The primary minor, the secondary minor, the compensating minor, and the spherical mirror are spaced from each other. A surface shape of each of the primary mirror and the secondary mirror is a quadric surface. The primary mirror is used as an aperture stop. A surface shape of the compensating mirror is a freeform surface. A surface shape of the spherical mirror is a spherical surface. A light emitted from a light source would be reflected by the primary mirror, the secondary minor, the compensating mirror, and the spherical mirror to form an image on an image plane.

An example optical system includes freeform mirrors configured to receive light from an object and to reflect the light among the freeform mirrors to produce an optical image of the object having positive distortion. The freeform mirrors include non-rotationally symmetric mirrors. The optical system also includes an along-track scanner having a line of imaging sensors configured to receive the optical image of the object from the freeform mirrors and to produce an image of the object having the positive distortion.

An imaging apparatus includes a first reflection optical system and a second reflection optical system having mutually different optical axes, each of the first and second reflection optical systems includes a plurality of reflecting surfaces, a first imaging portion configured to receive an imaging light reflected by the first reflection optical system, a second imaging portion configured to receive an imaging light reflected by the second reflection optical system, a first member, a second member, and a frame. A part of the plurality of reflecting surfaces of the first reflection optical system are reflecting surfaces provided on the frame. Among the plurality of reflecting surfaces of the first reflection optical system, a final-stage reflecting surface configured to reflect the imaging light toward the first imaging portion is a first reflecting surface formed on a surface of the first member.

Dual-band optical imaging systems and methods. One example of a dual-band optical system includes an all-reflective shared optical sub-system configured to receive combined optical radiation including first optical radiation having wavelengths in a first waveband and second optical radiation having wavelengths in a second, different waveband, and an optical element positioned to receive the combined optical radiation from the all-reflective shared optical sub-system and having a dichroic coating configured to transmit the first optical radiation and to reflect the second optical radiation, the optical element being configured to transmit the first optical radiation toward a first focal plane and to reflect and focus the second optical radiation to a second focal plane. The all-reflective shared optical sub-system and the optical element are each positioned symmetrically about a primary optical axis extending between the first focal plane and the second focal plane.

An image offsetting apparatus for producing an offset image pathway and presenting the offset image pathway to an optic, including at least some of a mirror assembly wherein the mirror assembly comprises a first component mirror and a second component mirror, wherein the mirror assembly is attached or coupled so as to provide the offset image pathway that is offset from a direct image pathway between a target object and the optic.

An extreme ultraviolet light generation system according to one aspect of the present disclosure includes: a pulse laser apparatus configured to output a pulse laser beam, the pulse laser beam being supplied to a predetermined region in a chamber in which plasma containing extreme ultraviolet light is to be generated; a sensor configured to detect a beam size of the pulse laser beam; an actuator configured to change the beam size; and a controller. The controller performs, based on a first algorithm, first control that controls the actuator by a first control amount in a beam size minifying direction when the beam size has exceeded a first upper limit threshold in one burst duration, and then performs, based on a second algorithm, second control that controls the actuator by a second control amount smaller than the first control amount so that the beam size becomes closer to a target value.

An coronagraph optical system and method for continuously imaging a wide field of view that includes the Sun. Examples of the coronagraph optical system include an all-reflective foreoptics assembly that receives light rays from a viewed scene and a direct solar image of the Sun, a sensor assembly configured to produce an image of the viewed scene, an all-reflective relay optics assembly configured to receive the light rays from the foreoptics assembly and to reflect the light rays to the sensor assembly, and a solar rejection optical component positioned between the foreoptics assembly and the relay optics assembly and dynamically configurable such that the direct solar image of the Sun is reflected away from the relay optics assembly and the light rays are reflected to the relay optics assembly while an entrance aperture of the foreoptics assembly is continuously positioned towards the Sun.

An unobscured five-mirror afocal telescope includes an aperture configured to direct electromagnetic radiation to first, second, third, fourth and fifth mirrors, each configured to receive electromagnetic radiation and reflect electromagnetic radiation along a beam path. The five mirrors are arranged to sequentially reflect from one another electromagnetic radiation received via the aperture to produce a collimated output beam of the electromagnetic radiation at an exit pupil, with the five mirrors consisting of a three-element objective and a two-element eyepiece. A beam splitter may be disposed between the first mirror and the second mirror to direct short-wavelength electromagnetic radiation toward a device along a separate path.

An optical system (L0) that forms an image of an object and that includes an aperture stop (SP), a first reflection surface (R2), and a second reflection surface (R3) which are disposed in order from an enlargement side to a reduction side, an area of the first reflection surface is larger than an area of the second reflection surface, a reference axis is a path of a reference ray that passes through an opening center of the aperture stop to reach a center of a reduction plane, and an angle QPR (deg) between a line segment PQ connecting the opening center P and an intersection Q of the reference axis and the first reflection surface, and a line segment PR connecting the opening center P and an intersection R of the reference axis and the second reflection surface satisfies a predetermined condition.