Annuncio

Il terziario di ELT inizia a prendere forma

31 Gennaio 2020

L'ELT (Extremely Large Telescope) dell'ESO, il più grande occhio al mondo rivolto al cielo, avrà un sistema ottico pionieristico a cinque specchi che gli permetterà di svelare l'Universo con dettagli senza precedenti.Lo specchio terziario di questo sistema, M3, ha superato una fase cruciale di produzione e ora è stato consegnato alla società francese Safran Reosc per la lucidatura finale.

Ciascuno degli specchi dell'ELT rappresenta una sfida tecnologica significativa, a causa dell'estrema precisione richiesta in ogni fase della produzione per garantire una qualità ottica impeccabile. La società tedesca SCHOTT ha prodotto lo specchio grezzo perM3 - un blocco di un materiale vetroceramico noto come Zerodur che misura più di quattro metri da un bordo all'altro e pesa oltre tre tonnellate. Dopo aver fuso e lavorato il grezzo di M3 fino alla sua forma approssimativa, SCHOTT ha consegnato lo specchio a Safran Reosc, che ora lo livellerà e lo luciderà con una precisione di 15 nanometri su tutta la superficie ottica.

M3 è una caratteristica notevole dell'ELT. I telescopi più grandi, incluso il VLT (Very Large Telescope) dell'ESO e il telescopio spaziale Hubble della NASA/ESA, usano solo due specchi curvi per formare un'immagine, con a volte un piccolo specchio piatto, il terziario, introdotto per deviare la luce verso una punto focale più comodo. Nell'ELT invece anche lo specchio terziario ha la superficie curva, poiché l'uso di tre specchi curvi offre una migliore qualità dell'immagine su un campo di vista più ampio di quanto sarebbe possibile con un disegno a due specchi. Questa struttura consentirà all'ELT di produrre immagini del cielo notturno con una qualità senza precedenti.

I cinque specchi dell'ELT hanno tutti forme, dimensioni e ruoli diversi. Il principale, M1, è il più spettacolare, un gigantesco specchio concavo di 39 metri di diametro, composto da 798 segmenti esagonali, che raccoglieranno la luce dal cielo notturno e la rifletteranno sullo specchio secondario, M2. Con una dimensione di 4,2 metri di larghezza e una posizione sospesa sopra M1, M2 sarà il più grande specchio secondario mai utilizzato in un telescopio, nonché il più grande specchio convesso mai prodotto. Rifletterà la luce su M3, che a sua volta la trasmetterà a uno specchio piatto adattivo (M4) posto più in alto. Questo quarto specchio, che sarà il più grande specchio adattivo mai realizzato, regolerà la propria forma mille volte al secondo per correggere le distorsioni causate dalla turbolenza atmosferica. Infine M5, uno specchio piatto inclinabile, stabilizzerà l'immagine e la trasmetterà agli strumenti.

Contatti

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: pio@eso.org

Riguardo all'annuncio

Identificazione:ann20003

Immagini

Lo specchio grezzo M3 alla Safran Reosc
Lo specchio grezzo M3 alla Safran Reosc
Resa tridimensionale dello specchio terziario (M3) di ELT
Resa tridimensionale dello specchio terziario (M3) di ELT
Il sistema ottico dell'ELT con l'ubicazione degli specchi
Il sistema ottico dell'ELT con l'ubicazione degli specchi

Video

Il viaggio della luce attraverso i cinque specchi dell'E-ELT
Il viaggio della luce attraverso i cinque specchi dell'E-ELT

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