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Multilayer systems: Antireflecting systems, high-reflecting stacks and interference filters
VACUUM ( ' l a s s i f i e d : \ t ) s t r a c t~
Abstract No. .nd References
a~,IIl
III
Vacuum
Processing Contd.
Techniques
--
III
The Effect of Incident Atomic Velocity on the Structure of Evaporated Silver Films See A b s t r a c t
:Pa I l I
--
No.: 131 I
The Effect of the Substrate on the Crystallisation of Metallic Films U n i t e d .'ilales. T h i s w o r k w a s u n d e r t a k e n t o d i s c o v e r tile i m p o r t a n c e o f s u l ) s t r a t e s t r u c t u r e in d e t e r m i n i n g t h e c r y s t a l l i s a t i o n of t h i n m e t a l f i l m s c o n d e n s e d in v a c u u m . I t h a s a l r e a d y b e e n s h o w n t h a t s u r f a c e c r a c k s a c t as nucleation sites for condensing atoms. Films of gold, silver and zinc were deposited on various alkali halide s i n g l e c r y s t a l s u r f a c e s b y v a c u u m e v a p o r a t i o n t o a t h i c k n e s s ()f a b o u t 25 a t o m i c l a y e r s . T h e c r y s t a l s t r u c t u r e of t h e d e p o s i t e d film w a s v i e w e d u n d e r o b l i q u e i l l n m i n a t i o n u s i n g a n o p t i c a l m i c r o s c o p e , 140. S m a l l e r c r y s t a l l i t e s w e r e j u s t v i s i b l e a t t h i s m a g n i f i c a t i o n . F i h n s o n w a t e r - t ) o l i s h e d s u r f a c e s w e r e f o u n d t,) h a v e a u n i t e r m s t r u c t u r e ~f s m a l l c r v s t a l l i t e s , b u t f i h n s o n c r a c k e d a n d s c r a t c h e d NaCI a n d K B r s i n g l e c r y s t a l s s h o w e d g r o u p s of l a r g e r c r v s t a l l i t t , s. S c r a t c l m s w e r e d e l i t ) e r a t e l v m a d e w i t h a s a p p h i r e s t y l u s a n t i a d i a m o n d p o i u t , w h e n it w a s f o u n d t h a t r m v s t)f l a r g e c r v s t a l l i t e s w e r e f o r m e d o n e a c h s i d e of t h e s c r a t c h . S i m i l a r r o w s of crvstallites were ftmnd along a cleavage step. Specinlens heated after water-polishing also contained nucleation si{es f o r l a r g e c r y s t a l l i t e s , w h i c h w e r e f o u n d t o t ) c c u r s i n g l y , in c l u s t e r s , a n d in r o w s . S i m i l a r f i h n s w e r e also) det)t)sited o n t() w a t e r - p o l i s h e d s u r f a c e s w h i c h h a d b e e n k e p t for m a n y m ( m t h s , s h o w i n g t h a t t h e r e w a s l),)ssibly a r a t e of f o i - n l a t i o n of tile nllcleati(~ll s i t e s w h i c h c o u M be n l e a s u r e d . .\ q u a u t i t a t i v e s t u ( l y of t h e o c c u r r e n c e ()f c r v s t a l l i t e r o w s w a s t h e r e f o r e m a d e . R o w s of l a r g e n u c l e a t i o n s i t e s c o r r e s p o n d t o d e f e c t s in t h e o r i g i n a l c r y s t a l s u r f a c e , a b o u t w h i c h i n f o r m a t i o n w a s r e q u i r e d , i t w a s f o u n d t h a t t h e r a t e of f o r m a t i o n o t n u c l e a t i o n s i t e s o n cleaned polished surfaces varies rapidly with tcmperatnre. At room temperature the process takes months b u t a t t e m p e r a t u r e s a b o v e l e o ( t h e l)r()cess n l a v b e e o l n p l e t e a f t e r 1 hollr, w t l e n t h e d a t a al'e l ' e p r e s c n ~ e d b y a s e c o n d e q u a t i c m of tile refill ~{ KI ~1:z_ 1 I( I ..
.\rt ieh. I)y F. I. Metz & H. A. Lad .I. P h y s . Chem. 60, .March 1956 277.2~o
40,,III
w h e r e n a n d ll3c a r e t h e n u n l l l t ' r of rl)ws p e r tlnit a r e a a t t i m e ! a n d i n t i n i t c t i m e , a n d 1( is t h e r a t , ' eOllStallt. . \ e t i v a t i o n e n e r g i e s of 122 k c a l . a n t i Ra k e e l . w e r e f o u n d for N a C l a n d K B r r e s p e c t i v e l y . F u r t h e r e x p e r i m e n t s h o w e d t h a t s i t e f o r m a t i o n w a s a c c e l e r a t e d b v x - r a y b , ) m b a r d m e n t a n d b v t e n s i l e s t r e s s . In t h e d i s c u s s i o n , t h e r e l a t i o n s h i p of t h e n u c l e a t i o n s i t e s t o m o s a i c l ) o u n d a r i e s and s u r f a c e c r a c k s is d e a l t w i t h .
An X - R a y Study in High Vacuum of the Structure of Evaporated Copper F i l m s See A l ) s t r a c t N o . 1 3 3 I
41/III
The Automatic Recording of Electron Diffraction Patterns Applied to the Study of Evaporated Copper Layers See A b s t r a c t N o . : 5 4 I I
42'III
Stress Annealing in Copper Films See A b s t r a c t N o . : 1 3 4 I
13,III
Filmed Surfaces for Reflecting Optics See A b s t r a c t N o . : 99 I
44.'III
Article b y O. S. H e a v e n s l'hotogr. Sci. 4, , I a n . - F e b . 1956 21-24 45/III
Multilayer Systems: Antireflecting Systems, High-Reflecting Stacks and Interference Filters U n i t e d K i n g d o m . T h i s p a p e r d e a l s w i t h m u l t i l a y e r o p t i c a l i n t e r f e r e n c e s y s t e m s w h i c h a r e ot i m p o r t a n c e tn scientific photography. T h e c t m d i t i o n s n e c e s s a r y f o r t h e e x t i n c t i o n of r e t t e c t e d l i g h t f r o m a s u r f a c e a r e d e a l t w i t h , and t ) o t h s i n g l e a n d d o u b l e l a y e r a n t i r e f l e c t i o n c o a t i n g s a r e d i s c u s s e d . A s i m p l e d e t e r m i n a t i o n ()f t h e a m p l i t u d e of t h e r e f l e c t e d l i g h t m b o t h s y s t e m s is g i v e n u s i n g a v e c t o r d i a g r a m . B e c a u s e of t h e d i f f i c u l t i e s of n l a t c h m g t h e r e f r a c t i v e i n d e x of t h e s i n g l e d i e l e c t r i c a n t i r e f l e c t i o n c o a t i n g to t h a t of t h e g l a s s , c o m p l e t e e x t i n c t i o n w i t h t h e s i n g l e l a v e r is n o t u s u a l l y p o s s i b l e , b u t w i t h t h e t w o - l a y e r s y s t e m t h i s c a n a l w a y s b e a c h i e v e d f o r a p a r t i c u l a r w a v e l e n g t h a t a g i v e n a n g l e of i n c i d e n c e . A n o t h e r t y p e nf t w o - l a v e r s y s t e m is d e s c r i b e d w h i c h h a s a l o w e r a v e r a g e r e f l e c t i o n o v e r t h e w h o l e v i s i b l e s p e e t r u n l . I n s o m e i n s t r u m e n t s t h e r e is t h e n e e d f o r a m i r r o r w h i c h p a r t l y r e f l e c t s a n d p a r t l y t r a n s m i t s l i g h t . M e t a l films a r e i n e f t i c i e n t b e c a u s e o f t h e i r a b s o r p t i o n . All d i e l e c t r i c n o n - a b s o r b i n g l a y e r s i n a y b e b u i l t u p t o g i v e a v e r y h i g h r e t t e c t i o n w i t h l i t t l e a b s o r p t i o n . ( ) u a r t e r w a v e l e n g t h l a y e r s of z i n c s u l p h i d e a n d c r y o l i t e m a y b e s t a c k e d in t h i s w a y , b u t a r e n o t s u i t a b l e a s r e f l e c t o r s o v e r a w i d e b a n d , s i n c e t h e y a r e s e l e c t i v e . " I n t e r f e r e n c e f i l t e r s o f t h e F a b r y - P e r o t t y p e , c o n s i s t i n g of t w o h i g h l y r e t t e c t i n g s u r f a c e s s e p a r a t ( ~ d b v a s t ) a c i n g l a v e r a r e d i s c u s s e d . "l'he p a s s b a n d a n d b a n d w i d t h m a y t)e I r e ' determined, and the density gradient may be controlled, thus giving them many advantages over the'dye-tvptt o f filter w h e r e n a r r o w b a n d w i d t h s a r e d e s i r e d . F i l t e r s h a v i n g v e r y h i g h t r a n s m i s s i o n s a n d w M e r b a n d w i d t h may be obtained by using the all-dielectric stack already described.
Broad-Band Multilayer Film for Fabry-Perot Interferometers See A b s t r a c t
26~,
No.: 1 0 5 / I
Vacuum I'o/. V I
October, 1956
Abstract No. .nd References
a~,IIl
III
Vacuum
Processing Contd.
Techniques
--
III
The Effect of Incident Atomic Velocity on the Structure of Evaporated Silver Films See A b s t r a c t
:Pa I l I
--
No.: 131 I
The Effect of the Substrate on the Crystallisation of Metallic Films U n i t e d .'ilales. T h i s w o r k w a s u n d e r t a k e n t o d i s c o v e r tile i m p o r t a n c e o f s u l ) s t r a t e s t r u c t u r e in d e t e r m i n i n g t h e c r y s t a l l i s a t i o n of t h i n m e t a l f i l m s c o n d e n s e d in v a c u u m . I t h a s a l r e a d y b e e n s h o w n t h a t s u r f a c e c r a c k s a c t as nucleation sites for condensing atoms. Films of gold, silver and zinc were deposited on various alkali halide s i n g l e c r y s t a l s u r f a c e s b y v a c u u m e v a p o r a t i o n t o a t h i c k n e s s ()f a b o u t 25 a t o m i c l a y e r s . T h e c r y s t a l s t r u c t u r e of t h e d e p o s i t e d film w a s v i e w e d u n d e r o b l i q u e i l l n m i n a t i o n u s i n g a n o p t i c a l m i c r o s c o p e , 140. S m a l l e r c r y s t a l l i t e s w e r e j u s t v i s i b l e a t t h i s m a g n i f i c a t i o n . F i h n s o n w a t e r - t ) o l i s h e d s u r f a c e s w e r e f o u n d t,) h a v e a u n i t e r m s t r u c t u r e ~f s m a l l c r v s t a l l i t e s , b u t f i h n s o n c r a c k e d a n d s c r a t c h e d NaCI a n d K B r s i n g l e c r y s t a l s s h o w e d g r o u p s of l a r g e r c r v s t a l l i t t , s. S c r a t c l m s w e r e d e l i t ) e r a t e l v m a d e w i t h a s a p p h i r e s t y l u s a n t i a d i a m o n d p o i u t , w h e n it w a s f o u n d t h a t r m v s t)f l a r g e c r v s t a l l i t e s w e r e f o r m e d o n e a c h s i d e of t h e s c r a t c h . S i m i l a r r o w s of crvstallites were ftmnd along a cleavage step. Specinlens heated after water-polishing also contained nucleation si{es f o r l a r g e c r y s t a l l i t e s , w h i c h w e r e f o u n d t o t ) c c u r s i n g l y , in c l u s t e r s , a n d in r o w s . S i m i l a r f i h n s w e r e also) det)t)sited o n t() w a t e r - p o l i s h e d s u r f a c e s w h i c h h a d b e e n k e p t for m a n y m ( m t h s , s h o w i n g t h a t t h e r e w a s l),)ssibly a r a t e of f o i - n l a t i o n of tile nllcleati(~ll s i t e s w h i c h c o u M be n l e a s u r e d . .\ q u a u t i t a t i v e s t u ( l y of t h e o c c u r r e n c e ()f c r v s t a l l i t e r o w s w a s t h e r e f o r e m a d e . R o w s of l a r g e n u c l e a t i o n s i t e s c o r r e s p o n d t o d e f e c t s in t h e o r i g i n a l c r y s t a l s u r f a c e , a b o u t w h i c h i n f o r m a t i o n w a s r e q u i r e d , i t w a s f o u n d t h a t t h e r a t e of f o r m a t i o n o t n u c l e a t i o n s i t e s o n cleaned polished surfaces varies rapidly with tcmperatnre. At room temperature the process takes months b u t a t t e m p e r a t u r e s a b o v e l e o ( t h e l)r()cess n l a v b e e o l n p l e t e a f t e r 1 hollr, w t l e n t h e d a t a al'e l ' e p r e s c n ~ e d b y a s e c o n d e q u a t i c m of tile refill ~{ KI ~1:z_ 1 I( I ..
.\rt ieh. I)y F. I. Metz & H. A. Lad .I. P h y s . Chem. 60, .March 1956 277.2~o
40,,III
w h e r e n a n d ll3c a r e t h e n u n l l l t ' r of rl)ws p e r tlnit a r e a a t t i m e ! a n d i n t i n i t c t i m e , a n d 1( is t h e r a t , ' eOllStallt. . \ e t i v a t i o n e n e r g i e s of 122 k c a l . a n t i Ra k e e l . w e r e f o u n d for N a C l a n d K B r r e s p e c t i v e l y . F u r t h e r e x p e r i m e n t s h o w e d t h a t s i t e f o r m a t i o n w a s a c c e l e r a t e d b v x - r a y b , ) m b a r d m e n t a n d b v t e n s i l e s t r e s s . In t h e d i s c u s s i o n , t h e r e l a t i o n s h i p of t h e n u c l e a t i o n s i t e s t o m o s a i c l ) o u n d a r i e s and s u r f a c e c r a c k s is d e a l t w i t h .
An X - R a y Study in High Vacuum of the Structure of Evaporated Copper F i l m s See A l ) s t r a c t N o . 1 3 3 I
41/III
The Automatic Recording of Electron Diffraction Patterns Applied to the Study of Evaporated Copper Layers See A b s t r a c t N o . : 5 4 I I
42'III
Stress Annealing in Copper Films See A b s t r a c t N o . : 1 3 4 I
13,III
Filmed Surfaces for Reflecting Optics See A b s t r a c t N o . : 99 I
44.'III
Article b y O. S. H e a v e n s l'hotogr. Sci. 4, , I a n . - F e b . 1956 21-24 45/III
Multilayer Systems: Antireflecting Systems, High-Reflecting Stacks and Interference Filters U n i t e d K i n g d o m . T h i s p a p e r d e a l s w i t h m u l t i l a y e r o p t i c a l i n t e r f e r e n c e s y s t e m s w h i c h a r e ot i m p o r t a n c e tn scientific photography. T h e c t m d i t i o n s n e c e s s a r y f o r t h e e x t i n c t i o n of r e t t e c t e d l i g h t f r o m a s u r f a c e a r e d e a l t w i t h , and t ) o t h s i n g l e a n d d o u b l e l a y e r a n t i r e f l e c t i o n c o a t i n g s a r e d i s c u s s e d . A s i m p l e d e t e r m i n a t i o n ()f t h e a m p l i t u d e of t h e r e f l e c t e d l i g h t m b o t h s y s t e m s is g i v e n u s i n g a v e c t o r d i a g r a m . B e c a u s e of t h e d i f f i c u l t i e s of n l a t c h m g t h e r e f r a c t i v e i n d e x of t h e s i n g l e d i e l e c t r i c a n t i r e f l e c t i o n c o a t i n g to t h a t of t h e g l a s s , c o m p l e t e e x t i n c t i o n w i t h t h e s i n g l e l a v e r is n o t u s u a l l y p o s s i b l e , b u t w i t h t h e t w o - l a y e r s y s t e m t h i s c a n a l w a y s b e a c h i e v e d f o r a p a r t i c u l a r w a v e l e n g t h a t a g i v e n a n g l e of i n c i d e n c e . A n o t h e r t y p e nf t w o - l a v e r s y s t e m is d e s c r i b e d w h i c h h a s a l o w e r a v e r a g e r e f l e c t i o n o v e r t h e w h o l e v i s i b l e s p e e t r u n l . I n s o m e i n s t r u m e n t s t h e r e is t h e n e e d f o r a m i r r o r w h i c h p a r t l y r e f l e c t s a n d p a r t l y t r a n s m i t s l i g h t . M e t a l films a r e i n e f t i c i e n t b e c a u s e o f t h e i r a b s o r p t i o n . All d i e l e c t r i c n o n - a b s o r b i n g l a y e r s i n a y b e b u i l t u p t o g i v e a v e r y h i g h r e t t e c t i o n w i t h l i t t l e a b s o r p t i o n . ( ) u a r t e r w a v e l e n g t h l a y e r s of z i n c s u l p h i d e a n d c r y o l i t e m a y b e s t a c k e d in t h i s w a y , b u t a r e n o t s u i t a b l e a s r e f l e c t o r s o v e r a w i d e b a n d , s i n c e t h e y a r e s e l e c t i v e . " I n t e r f e r e n c e f i l t e r s o f t h e F a b r y - P e r o t t y p e , c o n s i s t i n g of t w o h i g h l y r e t t e c t i n g s u r f a c e s s e p a r a t ( ~ d b v a s t ) a c i n g l a v e r a r e d i s c u s s e d . "l'he p a s s b a n d a n d b a n d w i d t h m a y t)e I r e ' determined, and the density gradient may be controlled, thus giving them many advantages over the'dye-tvptt o f filter w h e r e n a r r o w b a n d w i d t h s a r e d e s i r e d . F i l t e r s h a v i n g v e r y h i g h t r a n s m i s s i o n s a n d w M e r b a n d w i d t h may be obtained by using the all-dielectric stack already described.
Broad-Band Multilayer Film for Fabry-Perot Interferometers See A b s t r a c t
26~,
No.: 1 0 5 / I
Vacuum I'o/. V I
October, 1956