A sight glass apparatus for viewing the interior of a pressurised vessel, chamber or a pipe conveying fluid under pressure is described. The sight glass apparatus comprises a sight glass assembly mounted over an opening into the vessel, chamber or pipe, the sight glass assembly comprising a sight glass adjacent the opening which provides a window to the inside of the vessel, chamber or pipe, and a containment vessel mounted behind and/or around the sight glass assembly for containing fluid exiting the opening in the pipe in the event that the sight glass assembly fails. In this way, even if the sight glass assembly fails, the pressurised fluid within the pressurised vessel, chamber or pipe is safely contained. In addition, a secondary sight glass can be provided behind the first, with a liquid or gel, or minimal gap, between the primary and secondary glasses to reduce the likelihood of a failure in the first sight glass triggering failure of the second sight glass, and/or a valve can be provided to automatically isolate the pressure system upon a sight glass failure.

Machine-readable symbol reader systems including one or more shields are provided. One example machine-readable symbol reader system includes a conveyor system to convey objects bearing one or more machine-readable symbols past a first region that is transmissive to light. The system includes a machine-readable symbol reader having a housing, a window formed in the housing, and at least one optical sensor received in the housing and having a field of view that extends outward of the window, at least the window of the machine-readable symbol reader positioned relatively below the conveyor system with the field of view aligned with the first region of the conveyor system. The system can further include a shield having a frame with a plurality of apertures that are transmissive to light, the shield positioned relatively below the first region and positioned relatively above the window of the machine-readable symbol reader.

Plasma viewports for high-temperature environments in semiconductor processing equipment are disclosed; such viewports may use a triple-window design, with each window providing particular functionality.

A thermal imaging system is provided. The thermal imaging system includes an explosion-proof housing with an optical window configured to contain an explosive pressure. The optical window allows electromagnetic thermal energy to pass. A thermal imaging sensor is disposed within the explosion-proof housing. Thermal imaging electronics are coupled to the thermal imaging sensor and configured to provide at least one thermal image based on a signal from the thermal imaging sensor. A lens assembly is disposed at least in front of the optical window external to the explosion-proof housing. A composite optical window for thermal imaging is also provided. In another embodiment, a thermal imaging system includes an explosion-proof housing having an optical window configured to contain an explosive pressure. An infrared (IR) camera is disposed within the explosion-proof housing. A reflector reflects electromagnetic thermal energy to the IR camera, but prevent an object from impacting the optical window.

Plasma viewports for high-temperature environments in semiconductor processing equipment are disclosed; such viewports may use a triple-window design, with each window providing particular functionality.

Metamaterial optics are integrated with vacuum-boundary walls of ultra-high-vacuum (UHV) cells to manipulate light in a manner analogous to various bulk optical elements including lenses, mirrors, beam splitters, polarizers, waveplate, wave guides, frequency modulators, and amplitude modulators. For example, UHV cells can have metasurface lenses formed on interior and/or exterior surfaces on one or more of their vacuum-boundary walls. Each metasurface lens can include a plurality of mesas with the same height and various cross-sectional dimensions. The uses of metasurface lenses allows through-going laser beams to be expanded, collimated or focused without using bulky refractive optics. Each metasurface lens can be formed on a cell wall using photolithographic or other techniques.

The present disclosure relates to a holder and a method of using an optical element, where the holder comprises a drawer having a base plate having an opening above which a seat is arranged in which an optical element is arranged, wherein a seal is arranged between a lower edge of the optical element and an inner lower end of the opening of the base plate of the drawer and a pressure ring is arranged around the seat, which has at least one projection on its underside which engages in at least one recess on the upper side of the base plate, and where the bottom of the at least one recess has a ramp with a seamlessly changing height in relation to an underside of the base plate. A laser processing head for laser material processing comprises at least one holder as described above.

Metamaterial optics are integrated with vacuum-boundary walls of ultra-high-vacuum (UHV) cells to manipulate light in a manner analogous to various bulk optical elements including lenses, mirrors, beam splitters, polarizers, waveplate, wave guides, frequency modulators, and amplitude modulators. For example, UHV cells can have metasurface lenses formed on interior and/or exterior surfaces on one or more of their vacuum-boundary walls. Each metasurface lens can include a plurality of mesas with the same height and various cross-sectional dimensions. The uses of metasurface lenses allows through-going laser beams to be expanded, collimated or focused without using bulky refractive optics. Each metasurface lens can be formed on a cell wall using photolithographic or other techniques.

A window assembly comprising: a frame defining an opening; a ceramic window; wherein the frame is bonded to the ceramic window to substantially cover the opening; and wherein the frame comprises two portions, wherein the thickness of a first portion of the two portions in the direction perpendicular to the main plane of the opening is smaller than the thickness of a second of the two portions in the direction perpendicular to the plane of the opening.