A flatness test of a float-glass optical window on top of a λ/10 optical flat. The window measures a flatness of 4–6λ per inch.
In optics, a window is an optical element that is transparent to a range of wavelengths, and that has no optical power. Windows may be flat or curved. They are used to block the flow of air or other fluids while allowing light to pass into or out of an optical system.
In general, an optical window is a material that allows light into an optical instrument. The material has to be transparent to a wavelength range of interest but not necessarily to visible light.[1] Usually, it is mechanically flat and sometimes it also is optically flat, depending on resolution requirements.[2] A window of this sort is commonly parallel[1] and is likely to be anti-reflection coated, especially if it is designed for visible light.[3] An optical window may be built into a piece of equipment (such as a vacuum chamber) to allow optical instruments to view inside that equipment.[4]
↑ Soares, Olivério D. D. (1987). Optical Metrology: Coherent and Incoherent Optics for Metrology, Sensing and Control in Science, Industry and Biomedicine. Springer Science & Business Media. p.347. ISBN978-94-009-3609-6. OCLC716678158.
↑ Auciello, Orlando; Krauss, Alan R. (2001). In Situ Real-Time Characterization of Thin Films. John Wiley & Sons. p.73. ISBN978-0-471-24141-6. OCLC804229641.
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