Anúncio

ESO adjudica contrato para o polimento do espelho terciário do ELT

15 de Fevereiro de 2017

O Extremely Large Telescope do ESO (ELT), que deverá começar a operar em 2024, encontra-se na vanguarda da tecnologia de telescópios. O seu sistema óptico será constituído por 5 espelhos separados, sendo cada um deles um desafio de engenharia.

O ESO acaba de adjudicar à companhia francesa Reosc [1], uma subsidiária da Safran Electronics & Defense, um contrato para o polimento do terceiro espelho colocado no caminho da luz, o M3. A Reosc receberá da SCHOTT o molde do espelho bruto e a partir daí conceberá o espelho final e as sua interfaces de montagem, polirá a superfície e levará a cabo todos os testes ópticos necessários antes de proceder à sua entrega [2]. Em julho de 2016 foram também adjudicados à Reosc os contratos para conceber, polir e testar o espelho secundário do telescópio e para fabricar as conchas de espelho deformáveis que constituirão o quarto espelho do ELT (M4).

O M3 será um espelho côncavo gigante de 3,8 metros de diâmetro — tão grande quanto os espelhos primários de muitos dos atuais telescópios mundiais de vanguarda. Este espelho constitui uma parte bastante invulgar do ELT, já que a maioria dos atuais telescópios grandes, tais como o Very Large Telescope do ESO e o Telescópio Espacial Hubble da NASA/ESA, usa apenas dois espelhos curvos ou, por vezes, um espelho terciário plano para redireccionar a luz para o foco apropriado. A superfície curva do M3 trabalhará em uníssono com os espelhos primário e secundário no intuito de garantir uma melhor qualidade de imagem num grande campo de visão.

O elemento estrutural do espelho, antes de lhe ser aplicada a sua superfície refletora, será feito de um material sofisticado chamado Zerodur™, da SCHOTT [3], que precisará depois de ser moldado e polido até uma precisão de 15 nanómetros.

Notas

[1] A Reosc, subsidiária da Sagem, uma companhia Safran de alta tecnologia, é líder mundial em design, produção e integração de óptica de alto desempenho, incluindo aplicações em astronomia (telescópios grandes), espaço (satélites), lasers de alta energia e indústria de semicondutores. A companhia construiu também os espelhos individuais de 8 metros para o Very Large Telescope do ESO e para os telescópios internacionais Gemini, o espelho de 11 metros para o Gran Telescopio de Canarias, espelhos para o instrumento europeu Nirspec do Telescópio Espacial James Webb da NASA e espelhos para o satélite astronómico da ESA, GAIA.

[2] O contrato para a moldagem do espelho M2 bruto foi adjudicado a 18 de janeiro de 2017.

[3] O material Zerodur™ foi originalmente desenvolvido  no final dos anos 1960 para uso em telescópios astronómicos. É um material que não apresenta quase nenhuma expansão térmica, mesmo no caso de grandes flutuações na temperatura, é altamente resistente em termos químicos e pode ser polido até um elevado grau de acabamento. A camada refletora propriamente dita, feita de alumínio ou prata, é normalmente vaporizada sobre a superfície extremamente lisa do espelho pouco antes do telescópio entrar em operação. Muitos telescópios com espelhos de Zerodur trabalham há décadas de forma bastante fiável, como por exemplo o Very Large Telescope do ESO, no Chile.

Links

Contactos

Marc Cayrel
ESO
Garching bei München, Alemanha
Tel:  +49 89 3200 6685
Email: mcayrel@eso.org

Peter Grimley
Assistant Public Information Officer
Garching bei München, Alemanha
Tel: +49 89 3200 6383
Email: pgrimley@partner.eso.org

Sobre o anúncio

Id:ann17005

Imagens

O sistema óptico do ELT onde se pode ver a localização dos espelhos
O sistema óptico do ELT onde se pode ver a localização dos espelhos

Vídeos

A viagem da luz através dos cinco espelhos do E-ELT
A viagem da luz através dos cinco espelhos do E-ELT

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