MIM #4 LIGHT TABLE PRE-HEATERS

Document Type:

CREST [1]

Collection:

NGA Records (Formerly NIMA) [2]

Document Number (FOIA) /ESDN (CREST):

CIA-RDP78B04770A002000050010-5

Release Decision:

RIPPUB

Original Classification:

Document Page Count:

Document Creation Date:

December 28, 2016

Document Release Date:

December 4, 2002

Sequence Number:

Case Number:

Publication Date:

February 13, 1970

Content Type:

File:

Attachment	Size
CIA-RDP78B04770A002000050010-5.pdf [3]	109.54 KB

Body:

Approved For Release 20 Q u CIA-RDP78B04770A002000050010-5 NPIC/TSSG/RED 25X11 13 February 1970 1 MEMORANDUM FOR: Chief, Research & Engineering Division, TSSG THROUGH : Deputy Chief, Research & Engineering Division, TSSG SUBJECT : MIM #4+ Light Table Pre-heaters REFERENCE : Memorandum from TSSG/ESD~ dated 30 January 1970 25X1 1. The purpose of the pre-heater circuit in the MTh #4 light table was not primarily to provide maximum luminance in the shortest time from start up. The purpose of the circuit was to provide flicker-free lumi- nance _kt normal operating luminance levels in the shortest time from start up. The higher the input power to the light grid, the faster the excita- tion gas warms to its most efficient operating temperature and the faster the arc stabilizes. At low power input levels, however, (where most viewing is done) the gas warms very slowly and the are requires a long time (a half-hour or so) to stabilize. The pre-heater was, therefore, incorpo- rated to aid in bringing the gas in the light grid up to operating temp- perature so it would not flicker. 'P by product of bringing the gas up to temperature faster was tht the ma,,,imum luminance could be reached sooner. The coolant system is actually detrimental to the lighting system perfor- mance at low light levels and therefore, must be compensated for by the heaters. 2. The problem of over cooling was noted in the prototype MIM #4 light table when the light was turned on at low power to "warm up" and it was found to be still flickering a half-hour later. The manufacturer ,suggested that the light, when just turned on, should be turned up to max- imum power for a half-hour before using the table at normal viewing levels. Discussions with potential Government buyers found IEG/NPIC willing to live with the problem, but DIA objected. As a result, 25X1] added the pre-heater circuit and both DIA and NPTC bought it. It was not a RED development. 3. It might be noted th,it in the original configuration of the light table the pre-heater was loc !ted in a rgst rvoir of coolant _,nd maintained a higher average coolant temperature (with the light off) than the present configuration. Nevertheless, the present heater system performs as ade- quately as the prototype system with the pump operating, and it maintains the proper lamp gas operating temperature even when the lamp is turned down. Declass Review by NIMA/DOD Approved For Relea 1p1/28 : CIA-RDp78;p:0477, Q42000050010-5 Approved For Release 2003/ ' l A-RDP78BO477OA002000050010-5 UBJECT: MIM #4+ Light Table Pre-he7 tern The point that is made in the referenced memorandum with regard to the pre- heater being superfluous tD attaining maximum brightness quickly is correct but without the heater system, flicker at low luminance levels could become a significant problem. I Distribution: Original - ddressee l 2 - TSSG/RED/SDB 25k1 NPIC/TSSG/RED 113 Feb 70 25X1 Approved For Release 2003/01/28: CIA-RDP78BO477OA002000050010-5 TSSG/R SDB