Particle irradiation tests on concave and Pyrex grating

Gunter, R. C., Jr.

English

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REFLICA GHATIMG STUDY 
MGR-22-091-002 
INTEH?!ii REFORT - PHASE VII 
S u l y  1, 1969 - June 30, 1970 
College  of the Holy Cross 
Wopcestav - Massp~kyusekts Q161n I 
https://ntrs.nasa.gov/search.jsp?R=19700031857 2020-03-11T22:39:28+00:00Z
REPLICA GRATING STUDY 
NGR-22-091-002 
INTERIM REFORT - PHASE V I I  
~ u l y  1, 1969 - June 30, 1970 
College of the Holy Cross 
Worcester, Massachusetts 01610 
Submitted by: 
REPLICA G X A T l N G  STUDY 
I N T ~ H ~ I . I  !IE;FGilT - PHASE V I I  
July 1, 1969 - June 30,  1970 
College of t h e  Holy Cross 
Worcester, Nassachusetts 01610 
Report Prepared by: Dr. ~ o y  C, k n t e r ,  J r e  
Contract No. : 
Date: July 1, 1970 
Page 
.. A b s t r a c t  .... ............................ 1 
1. Purpose of E f f o r t  .............................. 2 
2. Nature of E f f o r t  . . . . . . . . . . . . . . . . . . . . . . .e. .e. . . .  3 
3 . Conclirsions .................................. 5 
........ 4 . Plans For F'orthcoming Six-Month Per iod.  6 
5 . Persormel ..........-'............................ 8 
6 . Budget (Submit ted  ~ e p a r e t e ~ ~ )  
ABSTRACT 
- 
P a r t i c l e  i r r a d i a t i o n  t e s t s  were continued on concave 
g ra t ings ,  Tes t s  a f t e r  i r r a d i a t i o n  by a  Dynamitron Accelsr-  
a t o r  a t  l e v e l s  of 3.6 x 1014 and 3.6 x 1 0 l 5  e-/cm2 have been 
completed. A t  t he  lower i r r a d i a t i o n  l e v e l ,  a  lowering of t h e  
e f f i c i ency  of the g r a t i n g s  was observed, while any change i n  
beamwidths a t  h a l f  and t e n t h  power po in t s  f e l l  w i th in  our ex- 
perimental  e r r o r ,  A t  the  h igher  dosage, however, d e f i n i t e  
d e t e r i o r a t i o n  of some g ra t ings  was found. Also, a f u r t h e r  
genera l  lowering o f  g r a t i n g  e f f i c i ency  was noted, a s  a t  t h e  
lower i r r a d i a t i o n  l e v e l ,  
Beta i r r a d i a t i o n  of plane Pyrex g r a t i n g s  and s u b s t r a t e s  
by' s e l e c t e d  rad io i so topes  has been continued. An est imated 
dosage of 2.0 x 1015 e-/cm2 a t  energy l e v e l s  from 0.1 t o  2.0 
Piev produced no v i s i b l e  sur face  d i s t o r t i o n  upon i n t e r f e r o m e t r i e  
examination. 
1. PURPOSE OF EFFCRT -
1,l Thermal Vacu 
Work on the  thermal skid has been temporarily sus- 
pended, 
1.2 P a r t i c l e  1r rndia . t ion  
----.- 
Cumul-%tioe p a r t i c l e  i r r a d i a t i o n  of concave g r a t i n g s  
has  been contix~.led, Tes ts  on g ra t ings  a f t e r  i r r a d i a t i o n  
dosages of 3.6 x l 0 ~ ' 4  2nd 3.6 x 10 lS  o-/cm2 by a Dynam- 
i t r o n  Acc.el.erator have been completed. Thus we a r e  able  
t o  compare these resu1t.s with the r e s u l t s  previously 
obtained a f t e r  a s i m i l a r  i r r a d i a t i o n  of 3.6 x 1013 eW/cm2, 
These t e s t s  have been completed on f i v e  r e p l i c a  g ra t ings :  
two with BSC-2 su 'bs t ra tes ,  and two wi th  Pyrex s u b s t r a t e s  
and Dynasil  one wi th  a s u b s t r a t e .  With da ta  compiled 
e a r l i e r  i n  the pro,q.ram, the  f i n a l  i r r a d i a t i o n  l e v e l  
enables u s  t o  draw some d e f i n i t e  conclusions about 
g r a t i n g  d e t e r i o r a t i o n  and performance a t  these  h igh  i r-  
r a d i a t i o n  l e v e l s ,  
Lcw l e v e l  Get a i r r a d i z t i o n  by se lec ted  rad io i so topes  
has  contiruled i-n order  t o  find t he  poss ib le  e f f e c t s  of 
long-range w i  ae-spitct.rum i r r a d i a t i o n  on plane g r a t i n g s  
and surf'act .. 
2, NATURE OF EFFORT 
2e1 
The i r r a d i a t i o n  of plane Fyrex g r a t i n g s  and sub- 
s t r a t e s  by low i n t e n s i t y  radio iso tope  sources a s  descr ibed 
i n  the Phase I V  r e p o r t  has  continued, In te r fe romet r i c  
( Tq-man-Green type ) examination of t h e  i r r a d i a t e d  sur f  aces  
a f t e r  exposure t o  approximately 2,Cl x 1015 ew/cm2 a t  
energy l e v e l s  ranging from 0.1 t o  2,0 Mev showed no recog- 
n izable  sur face  d i s t o r t i o n .  As noted e a r l i e r ,  d i s c o l o r a t i o n  
of the s u b s t r a t e s  was observed a f t e r  i r r a d i a t i o n  with c e r -  
t a i n  r ad io i so topes ,  
2.2.2 - I r r a d i a t i o n  -.- - by Dynami t r o n  Accelerator  
.--- 
A s  noted i n  tho phase V I  r e p o r t ,  a f t e r  p a r t i c l e  i r -  
r a d i a t i o n  of 3.6 x 10'3 e-/cm2 the  g r a t i n g  s u b s t r a t e s  be- 
came di  sco?,ored. Likewise a f t e r  dos?-.?s of 3.6 x 1g14 and 
,-. 
3.6 x 1015 em/cmi, Pyrex and BSC-2 s u b s t r a t e s  became pro- 
g ress ive ly  darker  brown, while Dynaxil remained only bare ly  
clouded. In  the ?SC-2 subs t ra t ed  g r a t i n g s ,  a b l i s t e r i n g  
of t h e  g r a t i n g  sur face  was evident ,  looking l i k e  deep 
scra tches  i n  thc crstinp;, but  a c t u a l l y  being r a i s e d  r i d g e s ,  
This b l i s t e r i n g  e f f e c t  was a l s o  evident  beneath the g r a t -  
ing  sur face ,  looking l i k e  bubbles formed between the  sub- 
s t r a t e  and t h e  al1rrniqized coat ing,  This e f f e c t  caused 
such deterioration of  the  g r a t i n g s  that any results whatsoever 
were impossible t o  o b t a i n  f o r  one of the  g r a t i n g s ,  while  
only severely- l imi ted  q u a n t i t a t i  ve r e s u l t s  were obtained 
wi th  the  o t h e r ,  
Also,  a f t e r  the 3.6 x 1014 ea/cm2 i r r a d i a t i o n ,  t h e  
g r a t i n g s  were q u i t e  hot, t o  the  touch, remaining so  f o r  
some time af t~ : i r  the i r r a d i a t i o n  process was stopped. On 
the  subsequent i rr.ad5ation of 3.6 x 1015 e-/om2, s t e p s  
were taken t o  eliiTinnt,e th in  e f f e c t  t o  assure  u s  t h a t  no 
unnecessary tl-Leralal s traessing tot',: p lace  , A f t e r  t h i s  
l a s t  i r r a d i a t i o n ,  on7i, a ~ e n e r a l .  ,-:arming of the  g r a t i n g s  
was noticea'o1.e. 
,- 1 After  the 10LLC l e v e l  of i r r a d i a t i o n ,  no conclusive 
d e t e r i o r a t i o n  of gra t i t lp  n ~ r f o l ~ m a r c e  was noted wi th  r e spec t  
t o  h a l f  and t e n t h  power point;s, However, a genera l  lowering 
of g r a t i n g  eff.ic,ie.r.:cy was evident .  A l l  o t h e r  changes f e l l  
w i th in  our experimc :.ltal e r r o r ,  but  the  tendency seemed t o  
i n d i c a t e  better i ~ r a t i n g  r e so lu t ion .  
As mentioned sbovo,  i r r a d i a t j - o n  a t  a l e v e l  of 3,6 x 10 15 
e-/cmZ j u s t  about n l i n e d  those grat i r ips  wi th  DSC-2  s u b s t r a t e s .  
However, the Dynris i l  g r a  t 2  n g  showed a  def inj. t e  improvement 
i n  performance ove r  t h e  r e s u l t s  obtained a t  the  previous 
i r r a d i a t i o n  l e v e l ,  One of t h e  Pyx-ex g-ratings showed no 
change a t  a l l ,  whils  the  o ther  Pyrex g r a t i n g  showed a  
s l i g h t  d e t e r i o r a t i o n ,  All t h ree  of  t h e s e  g r a t i n g s  a l s o  
showed a small  20s:; i n  e f f i c i e n c y ,  
2,2,3 In te r fe romet r i c  Concave 
F 
Laser shear ing  in ter ferograms of the  i r r a d i a t e d  
g r a t i n g  su r faces  were taken,  No s i g n i f i c a n t  deformation 
of the g r a t i n g  sur faces  was noted, except i n  the  case  of 
the g ra t ings  with BSC-2 s u b s t r a t e s ,  A s  noted before,  
r idges  i n  t h e  g r a t i n g  surf'aces were p l a i n l y  v i s i b l e ,  How- 
ever ,  the  shear ing  i.nterferogranas ind ica ted  f u r t h e r  severe 
deformation of the g r a t i n g  su r faces ,  These r e s u l t s  a r e  
from comparisons of interferograms taken a f t e r  each 
successive i r r a d i a t i o n ,  with the BSC-2 deformation taking 
place a f t e r  t h e  3.6 x 1 0 ~ 5  e-/cm2 i r r a d i a t i o n  l eve l .  
2.2.4 Vacuum Test Bed 
Construct ion of the  s p e c i a l  Optical  Component 
Ilolder has been completed, Work on a  s u i t a b l e  cool ing  
mechanism f o r  the 0pt i .cal  Component Elolder i s  now under- 
way. 
3 ,  CONCLUSIONS T O  DATE -
In  our i r r a d i a t i o n  s t u d i e s ,  a  good degree of con- 
s i s t ency  of r e s u 1 . t ~  was found with r e spec t  t o  s u b s t r a t e  
types,  Manufacturer i n c o n s i s t e n c i e s  can thus  be ignored, 
I n  o ther  words, Pyrex g r a t i n g s ,  a s  an example, a l l  performed 
s i m i l a r l y  r ega rd less  of manufacturer, Also, even though 
t h e  3.rradiated gra t ings  were a c t u a l l y  hotter a f t e r  t he  
3.6 x 1014 e-/cm2 i r r a d i a t i o n  than a f t e r  the 10IS l e v e l ,  
and the more severe g r a t i n g  d e t e r i o r a t i ~ n  was a f t e r  t h e  
l a t t e r  dosage, t h e r n a l  e f f e c t s  o f  t h e  i r r a d i a t i o n  were 
probably l e s s  important than t h e  i r r a d i a t i o n  i t s e l f .  
Hence t h e  poor performance of the BSC-2 s u b s t r a t e s  a f t e r  
in tense  i r r a d i a t i o n  i s  s i p i f  i c a n t ,  Pyrex g r a t i n g s  seemed 
reasonably s t a b l e  fl.om o1.m t e s t s ,  while the Dynasil  a c t u a l l y  
seemed t o  improve, Fur ther  c o n c l u s i ~ n s  on t h i s  l a s t  sub- 
s t r a t e  can only be achie~red a . f t e r  f i ~ r t h e r  i r r a d i a t i o n .  A 
summary of  s e l e c t e d  g r a t i n g  da ta  af t c r  Dynarnitron ir-  
r a d i a t i o n  i s  shown i n  Table I. 
The shear ing  i.nt,erferogram~. p rov ided  a good method of 
f i n d i n g  surface a:istorti .ons,  a l though i n .  only the  case of 
tne  BSC-2 was t h e  method overwhelmlngl-g conclusive,  
Since most of the  area 02' daaase  i n  the BSC-2 
g r a t i n g s  seemed t o  be between the s u b s t r a t e  and the  
aluminized coat ing,  t h i s  m i g h t  be a s i g n i f i c a n t  a r e a  f o r  
inves t iga t ion .  
4 . PLANS - FOR THE FGRTI-ICGM1NG hIX-!ui.,;r\NTH FbRI OD s_l__r--m-- --. ---_r)rr__-- 
In accordance with discun::lons with t h e  P ro jec t  
Monitor and suSsequflnt receiklt of approval from him, 
emphasis i n  the forthcoming period w i l l  be s h i f t e d  t o  
r e f r a c t i v e  index s t u d i e s  of space  r e l a t ed -op t i c s ,  
(Selec ted  Data For 29~~51 Line of ~ e l i u m )  
I r r a d i a t i o n  Half -Power Tenth-Power 
Grat ing Le ve 1 Beamwidth Boamwidth Eff ic iency 
Substrate+: (x3.6e-/cm2 
- 
( A? 
--.------.---- 
(A') 
---------- 
($1 
Dynasil 0 
1013 
10x4 
0,615 
0 .514.8 
gross 
0,380 
0.502 
0.508 
0.612 
0,560 
0.588 
0 e l l 7 7  
0,lc65 
0,560 
0 e 490 
0eI$+6 
grass 
0.305 
0.395 
0,Ic27 
g rass  
.stSuffixed l e t t e r  i n d i c a t e s  manufacturer 
5 ,  PgRSONNEL 
--- 
S,1 Sen io r  S t a f f  
-- 
While each of t h e  s t a f f  p a r t i c i p a t e d  i n  some phase 
of a l l  t h e  t e s t s ,  t h e  p r i n c i p a l  a r e a  of r e s p o n s i b i l i t y  
of each i n : ~ e s t i g a t o r  i s  a s  shown: 
D r .  Roy C. Gunter ,  Jr., Holy Cross  Co l l ege - -p r inc ipa l  
i n v e s t i g a t a r .  
5,2 - Studen t  S t a f f  
-- 
Although many s t u d e n t s  have been involved i n  one 
phase o r  ano ther  of  t h e  program, t h e  fo l lowing  were t h o s e  
w i t h  s p e c i f i c  assignments:  
James F ieaup- - l ine  p r o f i l e s ,  i r r a d i a t i o n  t e s t s ,  i n t e r -  
f e r o m e t r i c  t e s t  bed,  and u l t r a - h i g h  vacuum t e s t  bed,  
John Lcsvreault--line p r o f i l e s ,  i r r a d i a t i o n  t e s t s ,  
i n t e r f e r o m e t r i c  t e s t  bed. 
5,3 a o r t  From Other L a b o r a t o r i e s  
-. - 
M r .  L e s t e r  Lowe, AFCRL--Irradiation t e s t s ,  
D r .  Pau l  Me Waters, D r .  Richard 3'. Woodcock, Mr, Samuel 
F. Walton, MP. Co l in  Y a t e s ,  C e n t r a l  Research Labora- 
t o r y  of American O p t i c a l  Company--glass s t r e s s i n g  
and t e s t s .  
M r .  Richard Schmit t  and co l l eagues  of t h e  J a r r e l P  Ash 
Company Grating L a b o r a t o r i e s - - r e p l i c a t i o n  and t e s t s ,  
D r .  Warren Sh ie lds  and Ply., R u s s e l l  Cowing of the 
New England Deaconess Hosp i t a l  Cancer Research 
I n s t i t u t e - - r a d i  oisotope measurements. 
D r ,  Eugene Coyner, E.1 . Dupont de Nemours--consul- 
tat;:i on on wide range thermal  r e f r i g e r a n t s ,  
D r .  Piartin Saepoff ,  Dynasil,  Inca--samples of 
Dynauil, 
M r ,  John D. Harker,  General E l e c t r i c ,  Inc. --samples 
of ~E125 arlc! GElS1.  
PIr. L ,  M. Dozllev, Obiens-Illinoi. s ,  Inc.  --samples of 
C e r v i t ,  


Replica grating study, phase 7 Interim report, 1 Jul. 1969 - 30 Jun. 1970

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