| 摘要 |
A lid includes a frame, a window which is transmissive to radiation and has a peripheral edge sealingly coupled to the frame, and thermal insulating structure which thermally insulates the peripheral edge of the window. In one embodiment, the thermal insulating structure includes a ring which is made of a thermal insulating material, and extends around the window. In a different embodiment, the thermal insulating structure includes an annular gap between the window and frame, the gap extending around the window. The lid may be part of a housing with a sealed chamber therein, where the window facilitates travel of radiation between the chamber and a location external to the housing.
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