Quantasyn provides absolute measurement of radiation flux in the range 1000 A to 4500 A and into the vacuum ultraviolet. This radiation detector cimbines the high quantum efficiency and inherent linearity of the silicon solar cell with the constant quantum response of the fluorescent organic compound liumogen

Gorstein, M.

Mc Williams, I. G.

Seward, H. H.

English

NASA Technical Reports Server

September 1969	 Brief 69-10443 
NASA TECH BRIEF 
NASA Teèh Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
The Quantasyn, an Improved Quantum Detector 
The advent of a wide variety of new electro-optical 
sensory systems for space guidance has placed in-
creasing emphasis on the need for simple and reliable 
radiometric measurements. It is, for example, neces-
sary to calibrate a number of devices which either 
simulate or detect stars, horizon phenomena, or 
man-made targets. Calibration of individual detec-
tors and sources, as well as entire systems, re-
quires measurements to at least 5-10% which is con-
sidered reasonably accurate for spectroradiometric 
results. , Compounding of any individual measurement 
errors may result in total system calibration errors 
of several times this amount. Thus, if an electro-
optical system is to operate successfully, accurate 
spectroradiometry techniques must be employed not 
only on components (detectors, lenses, simulated 
sources, and the like) but also on the entire system 
at each phase of its evolution. 
Three detectors have been in common use for such 
calibration: the thermopile, the photomultiplier, and 
the photocell but all suffer from limiting character-
istics. The thermopile suffers from relatively high 
noise and drift levels. Photomultiplier and photocell 
sensitivities are affected by applied voltage, tem-
perature, surface irregularities, direction and wave-
length of incident energy, and exhibit a dark current 
that requires a mechanical chopper. 
In view of these limitations, a detector for meas-
uring radiation in the range 1000 A to 4500 A called 
the Quantasyn has been developed. This device 
combines the high quantum of efficiency and inherent 
linearity of the silicon solar cell with the constant
quantum response of the fluorescent organic, com-
pound liumogen. Liumogen (2, 2'-dihydroxy-1, l'-naph-
thaI diazine) is a member of a class of fluorescent 
phosphors which emit a constant number of photons 
per incoming exciting quanta. Liumogen is more 
practical for use with silicon than most of the other 
phosphors for a number of reasons: I) the emission 
spectrum of liumogen more nearly matches the highest 
sensitivity of the silicon, 2) the index of refraction 
of liumogen is reasonably well matched to that of 
silicon in the emission wavelength band, so that 
interface reflections will be small, 3) liumogen is 
directly subliminable so that uniform layers of any 
desired thickness can be readily evaporated onto the 
silicon. 
Notes: 
L When calibrated, the Quantasyn provides abso-
lute measurement of radiation flux below 4500 A 
and into the vacuum ultraviolet with noise levels 
on the order of 1/100th of those of a thermopile. 
Additionally, it has no sensitivity to wavelengths 
above 12,000 A, the cutoff of the silicon detector, 
and thus stray energy problems are minimized. 
2. No further documentation is available. 
3. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Electronics Research Center 
575 Technology Square 
Cambridge, Massachusetts 02139 
Reference: B69-10443
(continued overleal) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000433 2020-03-16T18:01:17+00:00Z
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, 
Code GP, Washington, D.C. 20546. 
Source: Harold H. Seward and Ian G. McWilliams of
Massachusetts Institute of Technology
under contract to
Electronics Research Center
and Mark Gorstein of 
Electronics Research Center
(ERC- 10148)
[I 
Brief 69-10443 Category 01


The Quantasyn, an improved quantum detector

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