Perfektní obrázek zrcadla
Udržet ESO Very Large Telescope (VLT) na vrcholu hry není žádný lehký úkol. K pořízení snímků vzdáleného vesmíru ostrých jako břitva potřebuje každý z VLT čtyř Unit Telescopes (UTs) ultra-precizní, super-reflektivní a 8,2m široké zrcadlo. Avšak stejně jako většina věcí ani tyto zrcadla nemohou zůstat čistá navěky, jelikož jsou každou noc vystavena okolnímu prostředí... a tam začíná příběh dnešního Obrázku týdne.
Prach a další znečišťující látky ve vzduchu chilské pouště Atacama, kde se VLT nachází, pomalu končí na zrcadlech Uts, kdykoliv jsou otevřené štěrbiny kupolí. To pomalu ničí téměř perfektní povrch hliníku, který pokrývá každé zrcadlo, čímž je dělá méně reflektivní. Volně držící částečky se periodicky odstraňují postřikováním zmrzlého oxidu uhelnatého na zrcadla, ale nakonec stejně musíme vyměnit celou nanesenou vrstvu. To zabírá čas, úsilí a péči - proces začíná odstraněním 23t zrcadla a jeho odvozu z vrcholku hory, kde se teleskop nachází, do speciálního zařízení v základním táboře observatoře.
Zrcadlo je opatrně zkontrolováno na velké částice, tak jak optický inženýr Jaime González dělá na obrázku u UT2 zrcadla. Poté je stará vrstva kovu smyta pryč pomocí kyselin, aby se odhalil tovar zrcadla po ním - ten je vyroben z unikátního sklokeramického hybridního materiálu zvaný Zerodur®. Jakmile je tovar suchý, je na něj nanesen vaporizovaný hliník, který ztvrdne do rovného povrchového kovového krytí, jež je tlusté pouze 80 nanometrů (to je 1000 tenčí než lidský vlas). Poté inženýři zkontrolují nové krytí a změří jeho odrazivost. Až je zrcadlo schváleno k použití, je zrcadlo vyzdviženo zpět domů, kde se může vrátit zpět k udržování jasného dohledu nad vesmírem.
Kredit:ESO/N. Schafer
O snímku
| Id: | potw2539a |
| Jazyk: | cs |
| Typ: | Fotografický |
| Datum zveřejnění: | 29. září 2025 6:00 |
| Velikost: | 2624 x 3936 px |
O objektu
| Jméno: | Mirror, VLT Unit Telescopes |
| Typ: | Unspecified : Technology |
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