The interface circuitry described links the computer with the superconducting bolometer array. This helps demonstrate the feasibility of the array. Using the circuitry and the array, imaging will be made possible. Initial imaging will be done on laboratory objects, and the pixel characteristics will be investigated experimentally

Nelson, P. J.

English

NASA Technical Reports Server

NASA 
Technical 
Memorandum 
NASA TM-86581 
(NASA-TM-8658 1) 
INTERFACE CIRCUITRY FOR SUPERCONDUCTING 
BOLOMETER 
By P .  J .  N e l s o n  
Space S c i e n c e  L a b o r a t o r y  
S c i e n c e  and  E n g i n e e r i n g  Directorate 
J a n u a r y  1 9 8 7  
I N T E E F A C E  C I L C U J I B Y  FOP N8 7- 1 7  0 16 
S U P E R C O N D O C T I K G  E C L G f i E ' f E R  ( k A 5 A )  1 1  p 
CSCL 14B 
Unclas 
63/35 43&4S . 
NASA 
Nattonal Aeronautics and 
Space Adm,nistration 
George C. Marshall Space Flight Center 
MSFC - Form 3190 (Rev. May 1983) 
https://ntrs.nasa.gov/search.jsp?R=19870007583 2020-03-20T12:47:09+00:00Z
TABLE OF CONTENTS 
Page 
Introduction . . . . . . . . . . . . . . . . . . . . . . .  1 
Configuration . . . . . . . . . . . . . . . . . . . . . . .  1 
Conclusions . . . . . . . . . . . . . . . . . . . . . . . .  2 
LIST OF ILLUSTRATIONS 
Figure Title Page 
1 . Operational Amplifiers . . . . . . . . . . . . . . .  3 
2 . Comparator . . . . . . . . . . . . . . . . . . . . .  4 
3 . Counter . . . . . . . . . . . . . . . . . . . . . . .  5 
4 . Circuit Layout . . . . . . . . . . . . . . . . . . .  6 
5 . Complete Circuit Diagram . . . . . . . . . . . . . .  7 
iii 
TECHNICAL MEMORANDUM 
INTERFACE CIRCUITRY FOR SUPERCONDUCTING BOLOMETER 
INTRODUCTION 
The circuitry to be described evolved from a requirement to 
demonstrate feasibility of a new concept for reading out images 
from an array of bolometers. This concept, proposed by Palmer N. 
Peters and being co-investigated by Robert C. Sisk, is the basis 
for a Marshall Space Flight Center Director's Discretionary Fund, 
entitled "Superconducting Sensors for IR Astronomy Applications." 
One embodiment of the circuitry required has been finalized by 
this author as a project for the Marshall Space Flight Center's 
Professional Intern Program. 
The interface circuitry described in this report is used to 
link a computer with the superconducting bolometer array. Rows 
of resistive lines and columns of superconducting lines are uti- 
lized f o r  this array. When a current is passed through a resis- 
tive line, it produces heating, thus causing a transition to nor- 
mal conduction on the corresponding superconductors. 
When a radiation pattern is imaged on the array, a tempera- 
ture pattern unique to that radiation pattern is obtained. 
length of time that the heating must be applied before the super- 
conductor switches to a normal conductor is inversely propor- 
tional to the intensity of the infrared image projected on that 
element. The interface circuitry is designed to accommodate a 
16x16 array. The main purpose of this circuitry is to show the 
feasibility of the array. 
larger array than the initial 16x16 array. 
The 
Further applications will be on a much 
CONFIGURATION 
The circuitry, whose primary components were suggested by 
Robert W. Austin and Palmer N. Peters, was designed primarily in 
four stages. 
consist of amplifiers. The first stage amplifies the input sig- 
nal by a factor of 140 and the second stage amplifies by 10, 
thereby providing a total amplification of 1400. 
AMPS provide this gain (Figure 1). 
The first two stages of the interface circuitry 
Two OP27 OP- 
The next stage consists of a LN311 comparator that compares 
the voltage it sees with a predetermined reference voltage whose 
level can be adjusted (Figure 2). 
goes high (+5V) when the input signal, after being amplified 1400 
The output of the comparator 
times, is higher than the reference voltage. The comparator's 
output is negative logic ANDed with a gating signal provided from 
the computer. This enables control of the last stage in the cir- 
cuit, an MM74HC590 eight-bit binary counter. When the output of 
the comparator goes high, the counter stops counting. The count 
from the counter is then stored in the computer (Figure 3 ) .  
Since the count corresponds to the image from the array, the com- 
puter can then compile the counts of all 16 counters to 
reproduce one line of the image on the computer. 
There were several specifications to be considered when 
designing the interface circuitry. One of the primary factors to 
be considered was the signal level necessary to trigger the in- 
terface circuitry. With the appropriate adjustment of the poten- 
tiometer, the circuitry will trigger on a signal level as low as 
30 vV.  Since this is amplified 1400 times, the comparator sees 
42 mV. Several capacitors were added to reduce the level of 
noise in the circuit. Diodes were added to prevent possible 
damage to the chips should the power supplies be incorrectly con- 
nected. The supply voltages for this circuit are as follows: 
+5 v 
+12 v 
-12 v 
The final phase of the circuit involved etching a circuit 
board. A custom layout of the circuit was made, after which a 
circuit board was etched from the pattern of the layout (Figure 
4). Holes were drilled in the circuit board and the components 
were soldered in place (Figure 5). 
CONCLUSIONS 
The main purpose of this interface circuitry is to 
demonstrate the feasibility of the superconducting bolometer ar- 
ray. The circuitry described here ties the computer to the ar- 
ray. Initial attempts at imaging will be performed on laboratory 
objects, and the characteristics of the pixels will be inves- 
tigated experimentally. 
modified for astronomical or very weak signal sources to include 
phase-sensitive detection after chopping the signal. Both 
regulation at the transition temperature and fast Fourier 
analyses of the signal will be required for future very weak sig- 
nal applications. The relative simplicity of the readout tech- 
nique should permit easy scaling from the present 16x16 array to 
much larger arrays. 
The present circuitry will have to be 
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, APPROVAL 
INTERFACE CIRCUITRY FOR SUPERCONDUCTING BOLOMETER 
~y P .  J.  Nelson 
The i n f o r m a t i o n  i n  t h i s  report h a s  been  reviewed f o r  t e c h n i c a l  c o n t e n t .  
R e v i e w  o f  any i n f o r m a t i o n  c o n c e r n i n g  Department  o f  Defense  o r  n u c l e a r  e n e r g y  
a c t i v i t i e s  o r  programs h a s  been  made by t h e  MSFC S e c u r i t y  C l a s s i f i c a t i o n  
Of f i ce r .  T h i s  r e p o r t ,  i n  i t s  e n t i r e t y ,  h a s  been  de te rmined  t o  be u n c l a s s i f i e d .  
Deputy D i r e c t o r ,  Space S c i e n c e  Labora to ry  
/ TECHNIC 1. REPORT NO. 2. G O V E R N H N T  ACCESSION NO. 
NASA TM-86581 
4. T I T L E  AND S U B T I T L E  
I n t e r f a c e  C i r c u i t r y  f o r  Superconduct ing Bolometer 
7. AUTHOR(S) 
REPORT STANDARD T I T L E  PAGE 
3. RECIP IENT 'S  CATALOG NO. 
5. REPORT DATE 
J a n u a r y  1907 - 
6. PERFORMlNG ORGANIZATION CODE 
ES62 
8. PERFORMING ORGANIZATION REPOR r # 
P. J. Nelson" 
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT, NO. 
George C. M a r s h a l l  Space F l i g h t  Center  
M a r s h a l l  Space F l i g h t  C e n t e r ,  Alabama 35812 1 1 .  CONTRACT OR GRANT NO. 
13. T Y P E  OF REPOR;' & PERIOD COVERED 
12. SPONSORING AGENCY N A M E  AND ADDRESS 
N a t i o n a l  A e r o n a u t i c s  and Space A d m i n i s t r a t i o n  
Washington, D.C. 20546 
T e c h n i c a l  Memorandum 
1.3. SPONSORING AGENCY CODE 
1 
15. SUPPLEMENTARY NOTES 
Prepared by Space S c i e n c e  L a b o r a t o r y ,  S c i e n c e  and E n g i n e e r i n g  Directorate. 
*PIP on r o t a t i o n  i n  Space S c i e n c e  Labora to ry  from I n f o r m a t i o n  & E l e c t r o n i c  Systems 
T.ahnra t nrv 
16. ABSTRACT 
The i n t e r f a c e  c i r c u i t r y  d e s c r i b e d  i n  t h i s  r e p o r t  l i n k s  t h e  computer w i t h  t h e  
s u p e r c o n d u c t i n g  bolometer a r r a y .  T h i s  h e l p s  d e m o n s t r a t e  t h e  f e a s i b i l i t y  of t h e  
a r r a y .  Using t h e  c i r c u i t r y  a n d  t h e  a r r a y ,  imaging w i l l  be made possible. I n i t i a l  
imaging w i l l  be done on l a b o r a t o r y  o b j e c t s ,  and t h e  p i x e l  c h a r a c t e r i s t i c s  w i l l  be 
i n v e s t i g a t e d  e x p e r i m e n t a l l y .  
17. KEY WORDS 
S u p e r c o n d u c t i n g ,  I n t e r f a c e ,  Bolometer,  
Array 
19. SECURITY CLASSIF. (d thlm ropa(1 20, SECURITY CLA! 
18. DISTRIBUTION STATEMENT 
Unclas s i f i ed - -Un l imi t ed  
21. NO. OF PAGES 22. PRICE #IF. (Of thh  -go) 
I I 1 2  I NTI S U n c l a s s i f i e d  U n c l a s s i f i e d  


Interface circuitry for superconducting bolometer

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