An improved vidicon image sensor for space astronomy applications is developed that features reliably sealed ultraviolet transmitting windows and achieves acceptable photocathode quantum efficiency on these MgF2 windows. New preamplifier designs improve the dynamic range by reduction of the readout noise

Spitzer, L.

English

NASA Technical Reports Server

Mr. M. J. Aucremanne
PRINCETON UNIVERSITY OBSERVATORY
Princeton, New Jersey
FINAL REPORT -w 3 t
NSr-31-001-127 t o I
e+r Ht
"DEVELOPMENT AND EVALUATION OF TELEVISION TUBES o 1 o
FOR SPACE ASTRONOMY" H -A
for
NATIONAL AERONAUTICS AND SPACE AUIMINISTRATION M d 0
Washington, D.C. =00 H
May 10, 1974 H H l
PURPOSE o WM
Develop television type image sensors, sensitive in the visible and 0 U
ultraviolet, capable of long exposures at high spatial resolution, and other- r
wise suitable for space astronomy applications.
0
PERSONNEL
Principal Investigator - Prof. Lyman Spitzer
O
Research Staff - Mr. John L. Lowrance
Mr. Paul Zucchino
Mr. John Opperman . a
Mr. Patrick Murray 00 1
FISCAL STATUS
Value of Contract 464,958
Expenditures as of March 31, 1974 464,958
Balance -0-
https://ntrs.nasa.gov/search.jsp?R=19740013742 2020-03-23T09:50:55+00:00Z
2I. BACKGROUND
In 1964 Princeton University began a study of the best type of
television type image sensor for future space astronomy missions in the visible
and ultraviolet spectrum. This study concluded that the SEC-vidicon offered
the most overall potential. This was largely based on its ability to integrate
the photoelectron image for long periods of time as required in many astronomical
observations. This study was followed by a program to make ground based observa-
tions using an SEC-vidicon camera on the 36" telescope of the Princeton University
Observatory in order to indicate whether the SEC vidicon camera had the opera-
tional characteristics required for spectrophotometry and imaging. These
tests were encouraging and the program was continued to make improvements to the
television tubes that would make them more suitable for astronomical observations.
These improvements included reducing the internal background of the tube,
removing a mesh used to stabilize the KC1 target and working out a mode of
sequential operation that would still be safe. Considerable work was done to
develop a reliable way to seal the ultraviolet transmitting windows to the tube
and to achieve acceptable photocathode quantum efficiency on these MgF2 windows.
The tubes were redesigned to make them rugged enough to survive a rocket launch.
There was also considerable work on the magnetic deflection and focus coils for
the tubes. New preamplifier designs were developed to improve the dynamic range
by reducing the readout noise. The target assembly was redesigned to reduce
the microphonic signals and reduce the shunt capacitance to the rest of the tube
since this also affected the readout noise.
Figure 1 gives an overview of the chronological improvement in resolution
through the program.
3As the tubes improved, it became clear that they were not only good for
space applications but could be used to good advantage for some ground-based
observations. The camera was used on the Mt. Wilson 60" and the Mt. Palomar
200". It has also been used on a 36" at Kitt Peak and the 106" at McDonald
Observatory.
A substantial number of technical and scientific papers have resulted from the
program as noted in the attached bibliography.
The WX-31718 (40 mm, UV sensitive) has been flown in an Aerobee sounding
rocket and performed well, even after a parachute landing. The WX-31958 (7056
glass window version) has been used extensively by Princeton and others for ground-
based observing and is currently being incorporated in a balloon-borne telescope
that is a joint venture of the Netherlands and the NASA Johnson Spaceflight Center.
This program has been superseded by a program to develop a 70 mm version
of the tube for the Large Space Telescope.
II. STATUS OF SEC-VIDICON DEVELOPMENT
Figure 2 shows in schematic form the SEC-vidicon. A photoelectron from the
photocathode is accelerated by 8000 volts; strikes a target causing a charge
transfer across the target of approximately 50 electrons. The optical image is
integrated as an electrical charge pattern on the target. Following an exposure
the electron gun is turned on and the electron beam is scanned across the target
depositing electrons in those areas where electrons have been depleted by the
exposure. The image section and the electron gun are focused by a magnetic field.
Further details of the operation may be found in the references listed in the
bibliography.
Figure 3 shows the WX-32192 and WX-31718 which has a magnesium fluoride
window sealed to gold foil by frit glass. Table I lists the characteristics of
these tubes, as well as a smaller version developed for possible use on the
International Ultraviolet Explorer satellite. The photoelectric transfer function
for the IWX-31718 is shown in Figure 4.
Under NGR-31-001-236 and NAS5-20069 work is continuing to increase the
resolution and extend the dynamic range of these sensors.
BIBLIOGRAPHY
PUBLICATIONS
1. "Integrating Television Sensors for Space Astronomy," J. L. Lowrance and
P. Zucchino. Adv. in Electronics and Electron Physics, Vol. 28B, p. 851.
2. "Report on Evaluation of Television Tubes for Space Astronomy," J. L. Lowrance
and P. Zucchino. Dept. Publication: NASA RESEARCH CONTRACT: NSR 31-001-127
(1969).
3. "A Study of Telescope Maintenance and Updating in Orbit," W. Grantz, W. Wetherall,
N. Molesko and J. L. Lowrance. S.P.E.E. Seminar Proceedings on Space Optics,
Vol. 19, 1970.
4. "Progress Report on Development of the SEC-Vidicon for Astronomy," P. Zucchino
and J. L. Lowrance. Pub. Astronomical Use of Television-Type Image Sensors,
Symposium Proceedings, NASA SP-256, 1971.
5. "Development of Television Tubes for the Large Space Telscope", J. L. Lowrance
and P. Zucchino, Space Applications of Camera Tubes, International Colloquium
sponsored by Centre National D'Etudes Spatiales, Paris, Nov. 1971.
6. "Recent Developments and Applications of the SEC Vidicon for Astronomy,"
P. Zucchino and J. L. Lowrance. Adv. in Electronics and Electron Physics,
Vol. 33B, p. 801, Academic Press, London 1972.
7. "An Integrating Television System for Astronomy", D. C. Morton. Proceedings
of ESO/CERN Conference on Auxiliary Instrumentation for Large Telescopes,
Geneva, Switzerland, May 2, 1972.
8. "Large Space Telescope Television Sensor Development," J. L. Lowrance.
Advanced Electro-Optical Imaging Techniques, Proceedings of NASA HQ
Symposium, Washington, D. C. Sept. 22, 1972. NASA SP-338.
9. "The Use of Television Type Sensors in Astronomy;' Astronomical Observations
with Television Type Sensors. Proceedings of a Symposium held by Institute
of Astronomy and Space Science at University of British Columbia, Vancouver,
Canada, May 1973.
10. "Astronomical Television Development at Princeton University Observatory,"
presented at IAU Commission 9 Working Group on Astronomical Use of Image
Tubes, Sydney, Australia, 1973.
11. "Television Systems for Astronomical Applications," J. L. Lowrance with P.
Zucchino. Methods of Experimental Physics, Vol. 11, Academic Press, February
1974.
SCIENTIFIC PAPERS BASED ON ASTRONOMICAL OBSERVATIONS WITH THE TELEVISION SENSORS
DEVELOPED UNDER THIS CONTRACT.
1. Bernat, A., Ferland, G., Robbins, R. R., and Crane, P. 1973, "SEC-Vidicon
Slitless (0 II) Image of NGC 2440", BAAS 5, 423 and Ap.J. (in prep.).
2. Crane, P. 1971, "Photometry of Galaxies with Integrating Television",
BAAS 3, 399.
3. Crane, P. 1973a, "Surface Photometry of SBO Galaxies", BAAS 5, 349.
4. Crane, P. 1973b, "The SEC-Vidicon as a Photometer in Astronomical Observation
with Television Type Sensors, ed. by J. W. Glaspey and G. A. H. Walker
(Vancouver, B.C.) pp. 391.
5. Davidson, K., Crane, P., and Chincarini, G., "TV Photometry of Filaments
in the Crab Nebula (in press).
6. Lowrance, J. L., Morton, Donald C., Zucchino, Paul, Oke, J. B., and Schmidt,
Maarten, "The Spectrum of the Quasi-Stellar Object PHL 957", Ap. J. 171,
January 15, 1972, pp. 233-251.
7. Morton, Donald C. and Morton, Winifred A., "Absorption-Line Profiles in the
Quasi-Stellar Object PHL 957", Ap.J., Vol. 174, June 1, 1972, pp. 237-252.
8. Morton, Donald C. and Chevalier, Roger A. "Velocity Dispersions in Galaxies
I. The E7 Galaxy NGC 7332", Ap. J. 174, June 15, 1972, pp. 489-498.
9. Morton, W. A. and Morton, Donald C. "Absorption Lines in the Spectrum of the
Quasar Ton 1530", Ap.J., Vol. 178, No. 3, Pt. 1, December 15, 1972.
10. Morton, D. C. and Chevalier, Roger A.,"Velocity Dispersions in Galaxies. II. The
Ellipticals NGC 1889, 3115, 4473, and 4494.", Ap. J., Vol. 179, No. 1 Pt. 1,
January 1, 1973.
11. Morton, D. C. and Thuan, T. X., "Velocity Dispersions in Galaxies. II. The
Nucleus of M31". Ap.J., Vol. 180, No. 3, Pt. 1, March 15, 1973.
12. Morton, D. C. and Richstone, D. 0., "Absorption Lines in the Spectrum of the
Quasar Markarian 132", Ap.J., Vol. 184, No..1, Pt. 1, August 15, 1973.
CHRONOLOGY OF SEC-VIDICON RESOLUTION IMPROVEMENT
AT PRINCETON UNIVERSITY OBSERVATORY
No. of picture elements
Year at 50% MTF
1968 1.6 x 104
1969 4 x 105
1971 1I x 106
1972 4 x 106
1.0
Wc ith 2:1 zoom image section
0
t 0.8
c 1972
L.
0.6-
Uc 1968
0.4- 1971I--
0.2
S1969
-a
0 10 20 30 40 50
cycles/mm
Figure 1
WESTINGHOUSE WX 31718 SEC VIDICON
MAGNETIC FOCUS COIL MAGNETIC DEFLECTION COIL
PHOTOCATHODE-
8kV
1k15 V PREAMPLIFIER
TARGET STRUCTURE
BLACK Al
ANTIREFLECTION FIELD MESH
LAYER I
FLUFFY K CI TARGET IOU
700 A A12 0 3 SUPPORTING LAYER/ 700 A Al SIGNAL PLATE
Figure 2
___ ___ _ ___ ___ __ :ii L t x
Figure 3
SEC-VIDICONS
SEC VIDICON
PHOTOELECTRIC TRANSFER FUNCTION
6
10 25 pe 6250 pe
___ 
quantum noise
limited dynamic
range
10 -
40
4
10 - /A TARGET
O'/ GAIN
z /" 80
0 3
-J / ' c,10
J 1 0 p e E Q U IV A L E N T rm s
PREAMPLIFIER NOISE
10 OL (PA)I0 - o
5 pePA=N 6250pe full target
I 25 pePA
110 10 2  10 3  104  10 5
PHOTOELECTRONS PER 50 .LM SQUARE PIXEL
Figure 4
Table 1
WX-32192 WX-31718 Wx-
Large Medium Small
SEC-vidicon SEC -vidicon SEC -vidicon
Photocathode 76 mm 38 mm 25 mm
Diameter 110 mm
Target Size 56 x 51 mm 25 x 25 mm 15 x 15 mm
Overall Length 487 mm 432 mm 240 mm
Maximum Diameter 128 mm 80 mm 58 mm
Window MgF2  MgF2  MgF2
Glass Glass Glass
Focus Field 80 gauss 80 gauss 80 gauss
Resolution 
-0 cycles/mm 20 cycles/mm 20 cycles/mm(?)
(500 modulation)
No. Picture Elements 4 x 10 10 3.6 x 10
Photocathodes NaK Sb NaK Sb NaK Sb
S-20 ER S-20 ER CsTe
S-20 ER
n ACKGO RnU t
In 194 Princeto n University began a study of the best type oftelevision tle .iage sensor f'or ftbeeeotelevision tpe imae sesor for fute space astronomy missions in the visible
and ultraviolet spectrLu. This study concluded that the SEC-vidicon offeredthe most overall potential. This was largely based on its ability to integrate
the photoelectron image for long periods of time as required in many astronomical
observations, This study was followed by a program to make ground based observa-tions using an SEC-vidicon camera on the 36" telescope of the Princeton University
Observatory in order to indicate whether the SEC vidicon camera had the opera-
tional characteristics required for spectrophotometry and imaging. These
tests were encouraging and the program was continued to make improvements to thetelevision tubes that would make them more suitable for astronomical observations.
These improvements included reducing the internal background of the tube,
removing a mesh used to stabilize the KCl target and working out a mode ofsequential operation that would still be safe. Considerable work was done to
develop a reliable way to seal the ultraviolet transmitting windows to the tubeand to achieve acceptable photocathode quantum efficiency on these iMgF 2 windows.
The tubes were redesigned to 
-make them rugged enough to survive a rocket launch.There was also considerable work on the magnetic deflection and focus coils for
the tubes. New preamplifier designs were developed to improve the dynamic rangeby reducing the readout noise. The target assembly was redesigned to reduce
the microphonic signals and reduce the shunt capacitance to the rest of the tube
since this also affected the readout noise.
Figure I gives an overview of the chronological improvement in resolution
through the program.


Development and evaluation of television tubes for space astronomy

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