An inspection method for luminescent screens

VACUUM Classified A b s t r a c t s

I

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General Science and Engineering Contd.

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I

Ab~tr~ot ~-o. and References

Efficlency of the Fluorescence of a Number of Phosphors under Electronic Bombardment at 20kV Phosphor

O

~m %

R~ %

%

1

2

3

ZnS-10 ' Ag-C1

21

(0.50Zn, 0.50 Cd) 8-5 x I0-' Ag-G1

19.5

Zn0-Zn

7

Lm WR

Lm

4

5

tl

37

7

blue

98

yellow

340

24

green

500 85

7.5

Colouq"

WE

CAW04

3

80

3.5

70

2

blue

Ca0.Mg0.Si0r0.03Ti

7

91

7.5

70

5

blue

Zn 2Si04-0.004Mn

8.5

99

8.5

475

40

green

Zna(PO~)a-0.3Mn

5

100

5

170

8.5

red

2CaO.A1 ~03.Si0~-0.04Ce

4

9O

blue

account, tile r a d i a t i o n i n t e n s i t y of t h e screen at: t h e f r o n t c a n be e x p e c t e d to be 15 l m / ~ V w i t h o u t a l u m i n i u m b a c k i n g a n d 30 l m / W w i t h a l u m i n i u m b a c k i n g as long as t h e acceleration v o l t a g e is a t l e a s t 10 kV. Sommaire : U n e discussion est faite s u r le m ~ c a n i s m e de la l u m i n e s c e n c e c a t h o d i q u e et u n e description est donn~e de la m d t h o d e p e r m e t t a n t d ' e x a m i n e r la fluorescence des 6crans de tdl~vision.

Article by A. Bril H. A. Klasens, Philips Tech. Rev. i5, Aug. 53 (;3-72

A n Inspection Method for L u m i n e s c e n t Screens United Kingdom. A low p r e s s u r e h i g h v o l t a g e gas discharge w i t h i n a c a t h o d e r a y t u b e will excite l u m i n e s c e n c e in t h e screen. T h i s p h e n o m e n o n h a s b e e n i n v e s t i g a t e d as a possible basis for a m e t h o d of screen inspection. Sommaire: Des ddtails s o n t d o n n 6 s s u r u n e m 6 t h o d e p r a c t i q u e d ' i n s p e c t i o n des dcrans l u m i n e s c e n t s de t6Mviseurs, m d t h o d e qui p e u t ~tre combinde avec le proc4dd d ' a l u m i n i s a t i o n .

Letter by K, G. Burn Vacuum 3, Oct. 1953 415-417

R e v i e w of W o r k on Dichroic Mirrors and Their Light-Dividing Characteristics

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United Slates. T h e l i g h t - d i v i d i n g a c t i o n of dichroic m i r r o r s is b a s e d on t h e effect of interference in reflected a n d t r a n s m i t t e d light. I n order to achieve t h e desired a c t i o n a glass plate is coated w i t h a n u m b e r of interterence films e a c h v a r y i n g in t h i c k n e s s f r o m ¼ of tile w a v e l e n g t h of t h e light to ¼ of t h e w a v e l e n g t h of t h e light, T h e films a r e d e p o s i t e d b y e v a p o r a t i o n in a v a c u u m . F i r s t t h e action of a single t h i n film is considered. T h e interference effect of a ¼ w a v e l e n g t h film d e p e n d s on t h e v a l u e of t h e refractive i n d e x of t h e m a t e r i a l used. I n a d i a g r a m it is s h o w n t h a t a film of a refractive i n d e x h i g h e r t h a n t h a t of glass will t e n d to increase reflection a n d d i m i n i s h t r a n s m i s s i o n . A film w i t h a refractive i n d e x less t h a n t h a t of glass will t e n d to d i m i n i s h reflection a n d increase t r a n s m i s s i o n . If it is desired to o b t a i n a h i g h e r reflection for a specified w a v e l e n g t h t h a n is available f r o m a single film of a g i v e n r e f r a c t i v e index, a c o m p o s i t e film is u s e d consisting of several layers of a l t e r n a t i n g l y h i g h a n d l o w - i n d e x values. T h e t h i c k n e s s of e a c h is controlled so t h a t t h e initial reflected r a y s a t t h e specified w a v e l e n g t h are in p h a s e w h e n t h e y l e a v e t h e m u l t i p l e film. T h e reflection o b t a i n e d in t h i s m a n n e r is t h e n e q u a l to t h e s q u a r e of t h e s u m of t h e a m p l i t u d e s of t h e reflected rays. The reflection-transmission c h a r a c t e r i s t i c s of a t y p i c a l s e v e n - l a y e r film of t h i s kind, giving a m a x i m u m of 90 % reflection for l i g h t of 6,350A a t a n angle of incidence of 45 °, is s h o w n in a g r a p h . T h e l i g h t - d i v i d i n g c h a r a c t e r i s t i c s are g o v e r n e d b y t h e angle of incidence as a c h a n g e of t h e l a t t e r c a u s e s a c h a n g e of p a t h difference. Therefore, d u r i n g t h e d e p o s i t i o n process t h e glass s u p p o r t i n g t h e film is positioned a t a n angle to t h e p l a n e of t h e e v a p o r a t o r a n d a wedges h a p e d d e p o s i t is p r o d u c e d . I n use, t h e t h i c k e r p a r t of t h e film receives t h e light i n c i d e n t a t t h e g r e a t e s t angle. A d i a g r a m is s h o w n of t h e optical s y s t e m of a n RCA_ colour television c a m e r a w h e r e u s e is m a d e of interference m i r r o r s to divide t h e l i g h t into p r i m a r y colours a n d to c o m b i n e t h e p r i m a r y colours for m o n i t o r i n g p u r p o s e s . T h e films d i s c u s s e d so far are m a d e f r o m n o n - a b s o r b i n g materials. H o w e v e r , l i g h t - a b s o r b i n g m a t e r i a l s c a n be u s e d w i t h a d v a n t a g e in t r a n s m i s s i o n filters for t h e r e m o v a l of blue light a n d t h e t r a n s m i s s i o n of red a n d green light. B y d e p o s i t i n g first a r e l a t i v e l y t h i n l a y e r of low-index m a t e r i a l a n d s u b s e q u e n t l y a c o m p a x a t i v e l y t h i c k l a y e r of h i g h - i n d e x m a t e r i a l a film c a n be p r o d u c e d w h i c h reflects fairly e v e n l y t h e light of all w a v e l e n g t h s of t h e visible s p e c t r u m u p to 4 5 % . F i n a l l y t h e design of h e a t - t r a n s m i t t i n g m i r r o r s is discussed w h i c h reflect v i r t u a l l y all light of t h e visible s p e c t r u m . Sommaire : U n article s u r les derniers c o n n a i s s a n c e s a y a n t t r a i t 5~ Ia fabrication des miroirs dichroiques et leur p o u v o i r s d p a r a t e u r .

October, 195.3

Vacuum Vol. I 1 [ No. 4

211/1

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Paper by M. E. Widdop J.&M.P.T.E. 6o, April 53 357-366

440