Tiedote

ELT:n kolmas peili saavuttaa muotonsa

31. tammikuuta 2020

ESO:n Extremely Large Telescope eli ELT-kaukoputkessa, mistä tulee maailman suurin silmä taivaalle, tulee olemaan viisi peiliä käsittävä optinen systeemi, minkä avulla se pystyy tutkimaan Universumia ennennäkemättömällä tarkkuudella. Tämän systeemin kolmannen peilin M3:n tekemisessä on nyt saavutettu tärkeä vaihe ja se on toimitettu ranskalaiselle Safran Reosc yhtiölle lopullista kiilloitusta varten.

ELT:n jokainen peili on valtava teknologinen haaste, sillä tuotannon jokainen vaihe vaatii äärimmäistä tarkkuutta, jotta optiikka on täysin virheetöntä. Saksalainen SCHOTT yhtiö valmisti M3:n peiliaihion, mikä on keraamisesta Zerodurlasista valettu kappale, jonka koko on reunasta reunaan mitattuna neljä metriä ja painoltaan yli kolme tonnia. Valaamisen ja konetyöstön jälkeen peiliaihio on karkeasti oikean muotoinen. Tämän jälkeen SCHOTT toimitti peilin Safran Reosc:ille, joka tulee seuraavaksi hiomaan ja killoittamaan sen noin 15 nanometrin tarkkuudella koko optiselta pinnaltaan.

M3 on ELT:n erityinen ominaisuus. Useimmat suuret teleskoopit, kuten ESO:n Very Large Telescope eli VLT-kaukoputki ja NASA/ESA Hubble avaruuskaukoputki käyttävät kuvan muodostamiseen vain kahta kaarevaa peiliä. Joskus mukana on vielä kolmas tasainen peili, jonka avulla valo ohjataan sopivaan fokukseen. ELT:ssä kolmas peili on kuitenkin myös kaareva, koska kolmen kaarevan peilin avulla saadaan aikaiseksi parempi kuvanlaatu suuremmalle kuvakentälle, kuin vain kahta peiliä käyttämällä. Tällä suunnitelmalla ELT pystyy kuvaamaan yötaivasta ennennäkemättömällä tarkkuudella.

ELT:n viidestä peilistä jokainen on eri muotoinen, kokoinen ja niillä on eri tehtävät. Pääpeili M1 on kaikkein vaikuttavin. Se on jättimäinen 39-metrin kovera peili, mikä muodostuu 798:sta kuusikulmion muotoisesta segmentistä. Sen tehtävänä on kerätä valoa yötaivaalta ja heijastaa se M2 apupeiliin. Halkaisijaltaan 4.2 metrin kokoisena roikkuen M1:n yläpuolella M2 tulee olemaan maailman suurin teleskooppeihin liitetty apupeili, sekä suurin kupera peili, mitä on koskaan valmistettu. Se heijastaa valon takaisin M3:een, mistä valo kulkee edelleen sen yläpuolella olevaan tasaiseen adaptiiviseen M4 peiliin. Tämä neljäs peili tulee olemaan suurin koskaan valmistettu adaptiivinen peili. Sen muotoa voidaan muuttaa tuhat kertaa sekunnissa, jolloin ilmakehän turbulenssin aiheuttamat vääristymät kyetään korjaamaan. Tasainen käännettävä M5 peili vakauttaa kuvan ja ohjaa sen instrumenteille.

Yhteystiedot

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Saksa
Puh.: +49 89 3200 6670
Matkapuhelin: +49 151 241 664 00
S-posti: pio@eso.org

Tiedotteesta

Tunnistus:ann20003

Kuvat

M3 blank at Safran Reosc
M3 blank at Safran Reosc
Englanniksi
Rendering of ELT's tertiary mirror (M3)
Rendering of ELT's tertiary mirror (M3)
Englanniksi
The optical system of the ELT showing the location of the mirrors
The optical system of the ELT showing the location of the mirrors
Englanniksi

Videot

Light's five-mirror journey through the ELT
Light's five-mirror journey through the ELT
Englanniksi

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