Anúncio

Um espelho super fino para imagens estelares mais nítidas

Novo componente de óptica adaptativa entregue ao VLT do ESO

2 de Março de 2012

Um espelho extraordinariamente fino foi entregue ao VLT do ESO pela companhia francesa SAGEM. O espelho tem um diâmetro de 1120 milímetros, mas apenas 2 milímetros de espessura, o que o torna mais fino que a maioria dos vidros utilizados em janelas. O espelho tem que ser suficientemente fino para atuar praticamente como uma membrana flexível. Quando instalado no telescópio, o formato da sua superfície refletiva será constantemente e milimetricamente alterado, corrigindo os efeitos de distorção causados pela atmosfera terrestre, dando assim origem a imagens muito mais nítidas.

O espelho é composto por uma folha de material cerâmico polida de forma muito precisa. O processo de construção começa com um bloco de cerâmica Zerodur com mais de 70 milímetros de espessura, fornecido pela Schott Glass (Alemanha). A maior parte do material é desgastado para criar a fina casca final. O desafio é aplicar pouquíssima pressão e baixos níveis de stress no vidro durante o processo de polimento.

Produzir e testar um espelho tão grande e flexível é um grande desafio, mas a SAGEM foi bem sucedida ao controlar cuidadosamente os riscos do processo de construção e entregou um espelho fino que satisfaz os requisitos do ESO.

O novo espelho é o principal componente do espelho secundário deformável que irá substituir o atual espelho secundário de um dos quatro telescópios principais do VLT. Isso faz parte da nova Infraestrutura de Óptica Adaptativa para o VLT. O espelho secundário inteiro é construído em torno de um "corpo de referência" rígido (ann1056) e inclui um conjunto de 1170 atuadores, que aplicam uma força em 1170 imãns colados na parte de trás do espelho de casca fina. A forma da superfície refletiva do espelho será deformada mais de mil vezes por segundo pela ação dos atuadores de modo a corrigir os efeitos de turbulência da atmosfera terrestre e proporcionar imagens melhores e mais nítidas.

A Instalação de Óptica Adaptativa também utilzará a tecnologia de estrela guia laser que está a ser desenvolvida paralelamente (ann12012).

Desde 2004 que o ESO, com ajuda da Comissão Europeia, tem financiado esforços para o desenvolvimento do know-how em construção de espelhos de casca fina na Europa. O ESO está satisfeito em ver que estes esforços geraram frutos, graças à competência e determinação da SAGEM.

O novo espelho de casca fina e o sistema de óptica adaptativa ao qual ele faz parte, pavimentará o caminho para o próximo projeto do ESO: o European Extremely Large Telescope (E-ELT). Este trabalho está a impulsionar tecnologias avançadas como espelhos deformáveis com grande número de atuadores e a construção de espelhos de casca fina. Estas tecnologias podem ser aplicadas diretamente aos futuros telescópios da classe de 40 metros e ao projeto do E-ELT, que já inclui um espelho deformável de casca fina de 2,4 metros, inspirado no espelho deformável da Infraestrutura de Óptica Adaptativa do VLT.

Links

Contactos

Robin Arsenault
ESO, Germany
Tel: +49 89 3200 6524
Email: rarsenau@eso.org

Richard Hook
ESO, La Silla, Paranal and E-ELT Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Email: rhook@eso.org

Sobre o anúncio

Id:ann12015

Imagens

Espelho muito fino para a Infraestrutura de Óptica Adaptativa do Very Large Telescope do ESO
Espelho muito fino para a Infraestrutura de Óptica Adaptativa do Very Large Telescope do ESO
Espelho muito fino para a Infraestrutura de Óptica Adaptativa do Very Large Telescope do ESO
Espelho muito fino para a Infraestrutura de Óptica Adaptativa do Very Large Telescope do ESO

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