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Optical refers to principles that work in visible, ultraviolet, and infrared light. JWST is also primarily infrared telescope. It as some capability in red and
by nabla9 5y ago
Optical refers to principles that work in visible, ultraviolet, and infrared light.
JWST is also primarily infrared telescope. It as some capability in red and the yellow part of the visible spectrum.
- wolverine876 5y ago> Optical refers to principles that work in visible, ultraviolet, and infrared light. Is there something qualitatively different about infrared and ultraviolet that they share with visible, that they are all grouped into 'optical'?
- maxnoe 5y agoYes, you can use normal mirrors and lenses for these wavelengths
- wolverine876 5y agoThanks. How is 'normal' defined?
- nullc 5y agoMirrors, mostly yes. The situation for lenses is more complicated. Fused silica is falls off in the mid IR and is opaque for long wave IR, and optimizing for UV costs you IR response. ( https://escooptics.com/pages/materials-fused-silica-quartz https://escooptics.com/pages/materials-fused-silica-quartz ) The main optical path of JWST is all reflective for this reason. There are refractive optics in some the instruments, but those are more wavelength specific. E.g. NIRcam uses refractive elements made from LiF, BaF2, and ZnSe ( http://ircamera.as.arizona.edu/nircam/pdfs/5904-9_Ryder.pdf http://ircamera.as.arizona.edu/nircam/pdfs/5904-9_Ryder.pdf ) while I don't think MIRI ( https://arxiv.org/pdf/1508.02488.pdf https://arxiv.org/pdf/1508.02488.pdf ) uses any refractive components at all except a ZnS-GE double prism ( https://orbi.uliege.be/bitstream/2268/95768/1/DPA%20v8.pdf https://orbi.uliege.be/bitstream/2268/95768/1/DPA%20v8.pdf ) which is opaque to visible light.