[asac] [almanews] ALMA Memo 347 Released

[Carolyn White]

ALMA Memo #347

60 to 450 GHz Transmission and Reflection Measurements of Grooved
and Un-grooved HDPE Plates


G. A. Ediss * and T. Globus
February 2, 2001

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 the use of various plastic materials which
have reasonable absorption or scattering for the infrared wavelengths but
which have low loss at the signal wavelengths. One such material is HDPE,
for which some sort of anti-reflection coating would be required, and
because materials with the required refractive index are not available,
anti-reflection grooves are a possibility. To investigate the practicality
of such grooves, measurements have been made of un-grooved High Density
Polyethylene (HDPE), and of samples with linear or concentric rectangular
grooves and linear triangular grooves. At 75-110 GHz, measurements were
made with an HP8510 and between 60 and 450 GHz with a low resolution FTS.

View a pdf version of ALMA Memo 347:

     http://www.alma.nrao.edu/memos/html-memos/alma347/memo347.pdf

Download a postscript version of ALMA Memo 347:

     http://www.alma.nrao.edu/memos/html-memos/alma347/memo347.ps
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