Документ взят из кэша поисковой машины. Адрес оригинального документа : http://mavr.sao.ru/hq/lizm/conferences/pdf/1999/2000_2_p84-p86.pdf Дата изменения: Wed Feb 24 18:49:37 2010 Дата индексирования: Sat Jun 26 16:47:55 2010 Кодировка: Поисковые слова: m 5

Slicers for th e BT A Main Stellar Spectrograp h
G.A . Chountonov , E.I . Perepelitsi n
Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz 369167, Russia

Abstract . Thre e kind s o f slicer s hav e bee n develope d an d tested : a multifibe r slice r ( 7 fibers) , Bowen-Walrave n doubl e imag e slice r an d a lamella r slicer .

Th e imag e siz e o f a sta r i s generall y severa l time s large r tha n th e sli t widt h o f a high-resolutio n spec trograph . Thi s cause s losse s o f light . Imag e slicer s increas e th e efficiency o f spectra l ob servation s wit h resolutio n bein g preserved . Th e sta r light , whic h fail s t o fall withi n th e spectrograp h slit , i s cu t b y th e slice r int o stripe s whic h ar e transferre d the n b y optica l element s abov e o r belo w th e centra l par t o f th e sta r image . W e hav e teste d thre e kind s o f slicer s intende d t o increas e th e efficiency o f magneti c fiel d measure ments . Th e Mai n Stella r Spectrograp h (camer a 2) , whos e sli t i s normall y se t t o b e 0. 5 arcse c (0.4 5 mm) , wa s use d i n th e observations .

1 . A fibre bundl e slice r
Seve n fibre s o f 3 0 m i n length , eac h havin g a di , for m a rosett e a t on e en d an d ar e amete r o f 110 arrange d i n a ro w a t th e other . Th e forme r i s place d a t th e BT A prim e focu s t o receiv e ligh t fro m a sta r throug h th e matchin g optics . Th e latte r i s fastene d o n th e balcon y o f th e Nasmyth- 2 focus , an d th e ligh t emergin g fro m it s fibre s i s fe d vi a th e matchin g optica l elemen t int o th e spectrograp h throug h th e slit . Th e bloc k diagra m o f thi s typ e slice r i s show n i n Fig . la . I n Fig . l b a fragmen t o f th e spectru m i s represente d i n th e for m o f seve n dar k stripes . Th e cross-sectio n o f th e sta r spectru m i s give n i n Fig . lc . Th e radia tio n bein g wel l chaotic , th e gai n i n efficiency wit h thi s schem e i s no t larg e (a s show n i n Fig . la , onl y fou r fi bre s left an d righ t o f th e thre e vertica l fibre s ad d t o efficiency, bu t th e are a o f th e spac e betwee n th e fibre s account s for n o les s tha n 1 5 % o f th e total) . Th e man ufactur e an d installatio n o f suc h bundle s appeare d t o b e involved .

2 . Doubl e Bowen-Walrave n typ e slice r
Th e slice r measurement prim e focus liquid-crysta l (Fig . 2 ) i s use d for stella . Th e sta r ligh t comin g , afte r havin g bee n polarizatio n prism , i s r magneti c fro m th e divide d directe d t o fiel d BT A by a th e

© Specia l Astrophysica l Observator y o f th e Russia n AS , 200 0


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balcon y o f th e Nasmyth- 2 focu s throug h tw o fibre s 3 0 i n diameter . Ther e th e light , m i n lengt h an d 30 5 emergin g fro m th e fibr e ends , enter s th e spectrograp h slit . A doubl e Bowen-Walrave n typ e slice r installe d ahea d o f th e sli t cut s eac h o f th e image s o f th e fibr e en d face s int o fiv e stripe s an d arrange s the m alon g th e slit . I n Fig . 2 b i s demonstrate d th e spectru m o f th e regio n a s 1 0 dar k stripes : th e sta r Eq u i n th e uppe r fiv e stripe s correspon d t o th e left circula r po larization , th e lowe r fiv e t o th e righ t circula r polariza tion . Fig . 2c, d show s th e vertica l an d horizonta l sec -


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3. A la m in a t e d slicer T h e s l i c e r i s a s e t o f g l a s s p l a t e s 0 . 4 5 m m t h i c k , r e p r e s e n t i n g p a r a l l e l e p i p e d s o f d i f f e r e n t l e n g t h ( F i g . 3 a ) . T h e p l a t e s a r e s t a c k e d u p i n t o t w o b l o c k s s p a c e d b y 0 . 4 5 m m , s o t h a t t h e l i g h t o f t h e c e n t r a l p a r t o f t h e s t a r i m a g e e n t e r s t h e s p e c t r o g r a p h u n i m p e d e d . T h e d i s t i n g u i s h i n g f e a t u r e o f t h i s s l i c e r i s t h a t t h e s p e c t r a o f t h e s i d e e l e m e n t s t u r n o u t t o b e d i s p l a c e d w i t h r e s p e c t t o t h e c e n t r a l s p e c t r u m a l o n g t h e d i s p e r s i o n b y t h e v a l u e c o r r e s p o n d i n g t o t h e m u l t i p l e t h i c k n e s s o f t h e p l a t e . I n F i g . 3 b i s s h o w n t h e s e c t i o n o f t h e s t a r s p e c t r u m a c r o s s t h e d i s p e r s i o n . F i g . 3 c r e p r e s e n t s t h e n e t s p e c t r u m c o m p o s e d f r o m 9 s p e c t r a o f C V r e d u c e d p r e l i m i n a r y t o t h e c e n t r a l o n e . I n F i g . 4 t h e p h o t o g r a p h o f t h e l a m i n a t e d s l i c e r i s s h o w n . A c k n o w l e d g e m e n t s . T h e a u t h o r s e x p r e s s t h e i r t h a n k s t o G l a g o l e v s k i j Y u . V . a n d V l a s y u k V . V . fo r a d v o c a t i n g t h e w o r k a n d Z h u k o v s k i j V . N . fo r d e s i g n i n g t h e m e c h a n i c a l p l a t f o r m .

t i o n s , r e s p e c t i v e l y . T h e d i s a d v a n t a g e o f t h e B o w e W a l r a v e n t y p e s l i c e r i s t h e d e f o c u s i n g o f t h e i m a w h i l e t h e l i g h t i s b e i n g t r a n s f e r r e d f r o m t h e i n l e t f a o f t h e s l i c e r t o t h e s l i t , w h i c h i s a b o u t 0 . 1 s e c o n d a r c f o r o u r s l i c e r .

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