[asac][almanews] ALMA Memo 412 Released

[Stacy Oliver]

ALMA MEMO #412

"68.5 to 118 GHz Measurements of Possible Infrared Filter Materials: 
Black Polyethylene, Zitex, and Grooved and Un-Grooved Fluorogold and
HDPE"

G. A. Ediss and D. Koller/NRAO-CV

March 11, 2002

Keywords:  time domain measurements, infrared filter materials,
multilayer filters

For the ALMA production test receivers at present being designed in the
NRAO CDL, there is a need for infrared filters to reduce the thermal
loading.  One possibility is to use a plastic material which has
reasonable absorption or scattering for the infrared wavelengths but low
loss at the signal wavelengths.  Black polyethylene (polyethylene with
carbon filler) [1, 2], Zitex (expanded PTFE) [3], and Fluorogold (a
glass-filled Teflon) [4] have been suggested as such materials. 
Measurements at 68.5-118 GHz with an HP8510 have been made on room
temperature samples and multilayer filters (which were also measured at
liquid nitrogen temperature).  Measurements of grooved HDPE are also
reported (which resolve an inconsistency in our earlier measurements
[5]).

View a pdf version of ALMA Memo 412.
http://www.alma.nrao.edu/memos/html-memos/alma412/memo412.pdf

Download a postscript version of ALMA Memo 412.
http://www.alma.nrao.edu/memos/html-memos/alma412/memo412.ps
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