An optical system of the present disclosure includes: a first optical system including a polarization conversion element aligning a polarization direction of light including color light beams with a predetermined polarization direction, and generating illumination light including the color light beams; a first polarization rotation element disposed at a first pupil position inside the first optical system, including first and second divided regions, in which the first and second divided regions have different polarization characteristics with respect to a first color light beam outputted from the polarization conversion element; a polarizer disposed between the polarization conversion element and the first polarization rotation element, and reducing light in a polarization direction other than the predetermined polarization direction included in light outputted from the polarization conversion element; and light valves each illuminated by at least the first color light beam included in the illumination light generated by the first optical system.

A system comprises a sensor subsystem for imaging an object space, and a telescope for coupling electromagnetic energy from the object space to the sensor subsystem. The system comprises a bypass optical path that bypasses the telescope on the way to the sensor subsystem in order to provide a larger field of view of the object space. The bypass path and the telescope path merge at a merging point between the telescope and the sensor subsystem, and are disjoint upstream of the merging point. A simple bypass configuration is therefore provided, with possibly just a single fold mirror at the merging point. A sensor may form an intermediate image, and a frame is placed at the intermediate image to reject stray radiation and provide a real and accessible intermediate pupil for the sensor. Other features are also provided.

A stop, such as a numerical aperture stop, obscuration stop or false-light stop, for a lithography apparatus, includes a light-transmissive aperture and a stop element, in which or at which the aperture is provided. The stop element is opaque and fluid-permeable outside the aperture.

An apparatus includes a base that includes a raised surface and a first opening through the raised surface. The apparatus also includes a cover configured to be coupled to the base in order to form a cavity, where the cover includes a second opening through the cover. The raised surface is configured to allow passage of a first portion of optical energy through the first opening and to reflect a second portion of the optical energy. Portions of the cover and the base surrounding the cavity are configured to absorb the reflected second portion of the optical energy. The base may further include one or more baffles positioned around the raised surface, and/or the cover may further include one or more baffles positioned around the second opening.

Provided herein are approaches for cooling a process chamber window. In some embodiments, a system for process chamber window cooling may include a process chamber for processing a wafer, wherein the process chamber includes a window. In some embodiments, the window allows light from a lamp assembly to be delivered to the wafer. The system further includes a cooling apparatus operable with the process chamber, the cooling apparatus for delivering a gas to the window. The cooling apparatus includes a support ring supporting the window. The support ring includes a perimeter wall, and a plurality of slots formed through the perimeter wall. The plurality of slots may deliver a gas (e.g., air) across the window.

An apparatus includes a base that includes a raised surface and a first opening through the raised surface. The apparatus also includes a cover configured to be coupled to the base in order to form a cavity, where the cover includes a second opening through the cover. The raised surface is configured to allow passage of a first portion of optical energy through the first opening and to reflect a second portion of the optical energy. Portions of the cover and the base surrounding the cavity are configured to absorb the reflected second portion of the optical energy. The base may further include one or more baffles positioned around the raised surface, and/or the cover may further include one or more baffles positioned around the second opening.

An optical device for microscopic observation 4 comprises: a cold stop 13 having openings 13d, 13e corresponding to a low-magnification microscope optical system 5 and being a stop member arranged in a vacuum vessel 12 to let the light from the sample S pass to the camera 3; a warm stop 10 having an opening 14 corresponding to a high-magnification microscope optical system 5 and being a stop member arranged outside the vacuum vessel 12 to let the light from the sample S pass toward the cold stop 13; and a support member 11 supporting the warm stop 10 so that the warm stop can be inserted to or removed from on the optical axis of the light from the sample S, wherein the warm stop 10 has a reflective surface 15 on the camera 3 side and wherein the opening 14 is smaller than the openings 13d, 13e.

An optical device for microscopic observation 4 comprises: a cold stop 13 having openings 13d, 13e corresponding to a low-magnification microscope optical system 5 and being a stop member arranged in a vacuum vessel 12 to let the light from the sample S pass to the camera 3; a warm stop 10 having an opening 14 corresponding to a high-magnification microscope optical system 5 and being a stop member arranged outside the vacuum vessel 12 to let the light from the sample S pass toward the cold stop 13; and a support member 11 supporting the warm stop 10 so that the warm stop can be inserted to or removed from on the optical axis of the light from the sample S, wherein the warm stop 10 has a reflective surface 15 on the camera 3 side and wherein the opening 14 is smaller than the openings 13d, 13e.

A passive IR imaging system with a matrix-array detector in a cryostat includes a cold diaphragm, an image-forming device, of focal length that is continuously variable between F.sub.GC and F.sub.PC with, in this range of focal lengths, a constant numerical aperture and an aperture diaphragm level with the cold diaphragm, comprising a head group of fixed position and constant focal length with at least one lens in a mechanical holding means by the PC configuration, a first group and second group that are movable and positioned in order to ensure the change of focal length between and the focus of the image, an image-transport group of fixed position and of constant magnification, able to image the aperture diaphragm in order to limit the diameter of the PC useful beams on the lenses of the head group. The device comprises a TPC configuration with the first and second movable groups positioned to obtain the focal length F.sub.TPC, and its aperture diaphragm embodied in the mechanical holding means.

An optical system includes: a first optical system including a polarization conversion element aligning a polarization direction of light including color light beams with a predetermined polarization direction, and generating illumination light including the color light beams; a first polarization rotation element disposed at a first pupil position inside the first optical system, including first and second divided regions, in which the first and second divided regions have different polarization characteristics with respect to a first color light beam outputted from the polarization conversion element; a polarizer disposed between the polarization conversion element and the first polarization rotation element, and reducing light in a polarization direction other than the predetermined polarization direction included in light outputted from the polarization conversion element; and light valves each illuminated by at least the first color light beam included in the illumination light generated by the first optical system.