(Sanitized) IMPROVED LAMP PERFORMANCE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A001100080011-1
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 15
• Document Creation Date: December 28, 2016
• Document Release Date: December 27, 2004
• Sequence Number: 11
• Publication Date: August 1, 1970
• Content Type: LETTER

Approved For Release 2005/02/17 : CIA-RDP78BO477OA001 100080011 -1
August 1, 1970
STAT From:
Mailing Address:
STAT
Subject:
Improved Lamp Performance
Dear George:
Enclosed are four copies of Monthly Report No. 2 on
the subject contract. One copy has been forwarded directly
to the Contracting Officer.
Very truly yours,
WAS/ls
NGA Review Complete
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 STAT
August 1, 1970
MONTHLY REPORT #2
Improved Lamp Performance
1. Activity
1.1 Luminous Grids
Tests were made on two special phosphors and maximum
brightness levels were compared to standard phosphors with all
other conditions identical. The phosphors and relative bright-
ness levels were:
Relative
Brightness
Phosphor A
Standard Lumitone
Snow White 6500.
100%
Phosphor B
Modified Lumitone Snow
White 6500, etched.
103%
Phosphor C
Standard Sylvania
Sign White 5500.
100%
Pho
sp
hor D
Modified Sylvania Sign
White 5500. Blended with
red phosphor additives. No
observable color difference.
110%
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The phosphors were prepared by MERVAP Cold Light Products, Los
Angeles.
Note that the 6500 and 5500 phosphors were the same
efficiency. The 3% improvement obtained by etching the 6500
phosphor is not sufficient to permit recommending it. The 10%
improvement obtained by a special blend of the 5500 phosphor is
of interest since the cost differential in production is nominal.
It is expected to be no more than $5.00 per tube. A special grid
has been fabricated which has smaller diameter (consequently
higher intensity) outer strands in order to minimize brightness
fall off at the edges. Uniformity tests will be conducted next
period.
We have found that there are two grid parameters which
have a major significance relative to maximum brightness obtain-
able and dimming without flicker.
These parameters are grid temperature and the partial
pressures of the filling gas mixture. Tests have been conducted
on 4 grids fabricated to our specifications. The grids of course
all have mercury in them as it is the ultraviolet radiation of
the mercury vapor which excites the phosphor to radiate visible
light. The partial pressures of the additive gases are:
Grid 42D lmm helium
6mm Neon
2mm Argon
9mm
Standard Commercial
luminous tube mix.
6mm total partial pressure
of additive gases.
Grid 9 9mm Argon
Grid 12 12mm Argon
Preliminary data are presented on enclosed curves.
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Grid 42D appears to have the highest steady state brightness
and best low level flicker performance. An additional grid
is being prepared with the same mixture as grid 42D but with
slightly lower total partial pressure.
Further tests will be conducted on the best perform-
ing grid to determine the effect of grid temperature.
1.2 Lamp Box
Tests of high efficiency reflectors were previously
reported and no further work is contemplated. This does not
appear to be a fruitfull source of improvement in lamp performance.
Design of a-lamp box with a special ventilation pattern
is being prepared.
Standard design boxes have been received and will be
used for uniformity tests.
1.3 Diffuser
Tests of a selection of milk white plexiglass
(identical to lucite) diffusers have been conducted with very
promising results. The brightness is compared to that of 2447
at 2000 ft. Lamberts.
Formulation
Relative
Brightness
#2447
100%
#2159
114%
#2254
113%
#F`206?
119%
#2075
120%
Formulation #2075 had the highest transmission and brightness
however, it was possible to see the individual grid strands
through it. For this reason it is not considered satisfactory.
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Formulation #2067 had the next highest transmission and px?ovided
an excellent improvement in brightness. The diffuser had a
uniform appearance and individual grid strands could not be seen
though it. #2067 is not quite as readily obtained as #2447 but
there is no difference in cost. For the above reasons, Form-
ulation #2067 is recommended as a replacement for formulation
#2447 for general purpose diffuser use.
1.4 Dimmer
The effect of a step up thransformer was tested with
promising results. The response is linear as shown on attached
curve, Thus it appears that a step up transformer would be
suitable for increasing peak brightness for short periods of
time.
1.5 Transformer
As reported previously, half-wave dimmer tests proved
disappointing and no further work will be done in that area.
Further consideration has been given to a low cost
circuit for high frequency excitation but no circuit has-been
selected for test.
2. Planned Activity
Further tests will be run on various grids for maximum
brightness, flicker and uniformity.
Some convection cooled configurations will be tested.
Further consideration will be given to the high frequency chopper.
3. Other Comments
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July 16, 1970
W. O. 6847
PROGRESS REPORT
In re
1. ACTIVITY
1.1. Luminous Grids
Improved Lamp Performance
Tests with standard phosphor luminous grids indicate rather
good prospects for improving maximum brightness levels by improving
convection cooling. Setting the grids on end for maximum effective-
ness of convection currents results in about 5% higher leve~s as the
grid stablizes its temperature with the environment.. A grid has
been ordered with the outer strands of a smaller diameter than the
inner strands to determine whether that will minimize brightness
fall off at the edges.
1.2. Lamp Box
Two high efficiency diffuse reflectors have been tested with
disappointing results. The SM Codit reflective white was tested.
It is purported to be an extremely high efficiency reflector. The
brightness was about 28% less than flat white paint.
The second reflector consisted of a heavy layer of 10 micron
diameter glass beads. The brightness through the diffuser was about
1% less than flat white paint. It was noted that on observing the
glass beads directly that over a very narrow angle the light
reflection was quite bright but fell off rapidly with angle. It
is apparent that narrow angle high efficiency reflectors are not
effective for grid lamps.
l.S. Diffuser
A report of an extensive study of rear projection screen
materials was received through the courtesy of We
expect this report will be valuable as a guide o se ec a.ng e
most promising diffuser materials.
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1,4. Dimmer
A half wave dimmer was tested with disappointing results,,,
Compared to an identical full wave dimmer it was much more sensitive
to flicker at reduced voltage. We were actually able to obtain lower
light levels without flicker with the full wave dimmer than with the
half wave dimmer.. While it may be possible to solve the problem of
sensitivity to flicker of the half wave dimmer, it does not appear to
be a promising avenue of investigation.
1.5. Transformer
We have been reconsidering the frequency to be used for a
high frequency chopper. Since a major goal is to keep the manufactur-
ing cost at a competitive level, we are looking at components made
for television flyback sweep generators which operate at a standardized
frequency of 15,750 hertz. The cost of the components is low since
they are made in high production quantities.
2. PLANNED ACTIVITY
Tests will be run on other grids and other diffusers to
increase high level brightness and uniformity.
We will run further tests on convection cooled configurations.
A start will be made on the high frequency chopper.
3. OTHER COMMENTS
There are no unresolved technical problems. There were no
oral agreements or understandings or proposed changes to the contract.
There are no unanswered or unresolved matters. Status of funds is
indicated on the enclosed invoice.
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