(Sanitized) PRE-HEAT FEATURE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B05171A000200020201-3
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 28, 2016
• Document Release Date: February 17, 2004
• Sequence Number: 201
• Publication Date: February 19, 1970
• Content Type: MF

6LUKQ 1
Approved For Remise 2004/03/26 : CIA-RQP78B05171AQG0200020201-3
1.q 9 TSSG/RED-069-70
ebruarv 1970
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Chief, Research & Engineering Division
I have reviewed the situation concernin the re-heat fe ,ture and
leged usefulness or non-usefulness on the 910 Split format
Light Table-,and its anticipated use on the There seems to
be * great deft of confusion in this area. an a tempt to resolve this
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oonrusl.ot, have discussed this with the project officex5 on the 940 and
L5 Light Tables, respectively.
Light source. In order to permit the light source to operate in the
higher intensity r nge without e cessive e-,-.ternal heat, a liquid
plant system was introduced in the form of a Jacket surrounding the
I have contac ed Chief Engineer at j
The situation appears to e s allows:
a.The 0 Split Format Light Table has a 3,000 foot lambert
both resulting from insta'bi'lity of the light source. (i)
the light has a tendency to flicker when operated at low intensity.
Low intensity is necessary when viewing lair density transparencies.
(2) The light takes longer to reach maximum output; i.e., 3,000 foot
lamberts. High intensity is necessary when viewing high density
positives.
and more current to produ-e less and less light. Below 105"' the
e rise4 mu-,h above 1350, the efficiency quickly falls off requiring
The cold cathode lamp operates best at about 105?F. If the tem-
condense and puddle in the tube, resulting in an unstable
n, This lack of stability results in poor efficiency and unaccept-
able flickering.
e is some question as to the efficiency of utilizing the pre-
eature with regard to reaching maximum brightness more expeditiously.
ved, In the original installation, Q did not have the pump
Declass Review by NIMA/DOD
Approved For Release 2004/03/26 : CIA-RDP78BO5171A000200020201
SECRET
Z. while this liquia coolant system solves certain neating
em
49 s, it liquid prevented created an the cool additional cathode problem in light that source the presence of the
fntg its optimum operrting temperature, thereby, resulting iinly
in
bility of the light source.
GROd? I
from auiomaLc
~Excluded
3 downgrading and
declassification
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 Approved For Release 2004/0312~yg--DP78BO5171AQ,pY0200020201-3
when the pre-heat feature was on, thereby, depending exclusively
upon co ection--which would have been almost non-e intent; however, when
the lamp was turned on the pump was started and the pre-heat feature
li
effect, an auvfliary heater. The pre-heat feature was apparently
oul.d have been true if the pre-heat feature had not been available.
er
ently did help to stablize the lamp t the low intensity ranges ear
for one application but unsuccessful for the other.
fit. The current 15+4 Light Table has two pre-heat units of 125
+bach The ~ will run all of the time the pre-heat units are on.
uses ge combination of pre-heat units and fans, thermostatically controlled,
to maintain the lamp as close as possible to a standard 1050; i.e., that
temperature which the lamp operates most efficiently. IIis not
sure that ro-lyre-he:*t units are necessary. L?perimentation may indicate
th-t we din delete one of the units. Theory still indicates that n
e- cient. et'ineered re-heater might increase overall efficiency and
dppear that deleting the pre-heat feature would not prove advisable
woul
.
because it could greatly increase the instability of the lamp, particularly
in the low intensity ranges where this would be manifested as unacceptable
visual flicker. As i ecrrser;uenee. It doer not seem real.i.Qtic to follow this
Ppoadh At for time. Tale problem ac described In ' c memo was greatly
rpa tfi. and did not address the total problem. There are still too
%wW !d questions,
c
be potential instability 01 the light sour
e of the two ~-'heat unita can deleted by checking
both and then only a single unit worrking,
b. ise*nieet the pre-'beat feature entirely to determine the
romp ~ etude of any flickering problem that may result from
e in brie lower intensity
Det ne the efficiency of the nev S .. heat engineering
toe _.... ching high intensity Output quicker by comparing
the old prototype.
ulatione anti experiments to determine the following:
make the following reeOtrtmendatione. T` at, when ESD has
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I
Determine the actual current drain of the lamp alone vice
Determine the maximum current drain of the table
all of
that can operate concurrently do operate concurrently--
starting loads.
:d pre-heat features.
rimental data reet.lt3ng from these investigations should go
_.
long w towards dispelling the current confusion in this area.
a mm ''I `ic-'.etrt shod or reaching operating temperature w .thin a
does not have calculations or data covering any of these problems;
e n rs ie--to all practical purposes--an emperical approach to
.* id make one statement which could not be verified,
but on the sy. ace makes sense. feels that a pre-heat feat-are 25X1
n time frame; since the heat has to come from somewhere. The alter-
"; in effect utilizing it as a "low efficiency" heater.
vd be to pump vastly increased amounts of current into the lamp
DC/
Distri_buti.
Orig - Addressee
File ?/B
Cbrono
zciTSSG/RED/SDB/j
Approved For Release 2004/03/26
search & &gin
I(20 Feb 70)
ing Division,
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Pre-Heat Feature: