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High IR Transmission
The IR edge falls between 4.5 and 5.0 micrometers for a 1 mm thick sample.
GE 214/124 electrically fused quartz is a very efficient material for the transmission of infrared radiation. Its infrared transmission extends out to about 4 micrometers with little absorption in the “water band” at 2.73 micrometers. This makes Momentive Performance Materials’s electrically fused quartz different than flame fused quartz (often referred to as “wet” quartz). This difference is seen in the transmission for the IR range. The IR Transmission figure illustrates this difference.
Conversion to other thicknesses can be accomplished with the following formula:
T = (1-R)2 e -at
T = percent transmission expressed as a decimal.
R = surface reflection loss for one surface.
e = base of natural logarithms
a = absorption coefficient, cm-1
t = thickness, cm
(Please refer to the figure on the top right)
As the transmission curve illustrates, GE 214 fused quartz has a UV cutoff (1 mm thickness) at < 160 nm, a small absorption at 245 nm and no appreciable absorption due to hydroxyl ions. GE 219, which contains approximately 100 ppm Ti, has a UV cutoff at about 230 nm for a 1 mm thick sample.
(Please refer to the figures below)
The below chart represents exemplary and extrapolated transmission results for the noted materials. These results are for informational purposes only and should not be construed as a warranty or guarantee that any particular sample will exhibit the same results. Transmission values for a particular sample can vary based on a number of factors.