SPIRE Design Description - Research Services
SPIRE Design Description - Research Services
SPIRE Design Description - Research Services
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Draft <strong>SPIRE</strong> <strong>Design</strong> <strong>Description</strong> Document<br />
Figure 4-27 shows a prototype photometer 350-µm band filter chain transmission profile on linear and<br />
logarithmic plots. The optical and UV transmissions of the individual elements have been measured<br />
separately and multiplied together to derive the overall transmission. The horizontal lines on the logaritmic<br />
plot indicate the out-of-band rejection requirements, which are comfortably met by the filter chain.<br />
Transmission<br />
Transmission<br />
1.0<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
0.0<br />
1.E+00<br />
1.E-03<br />
1.E-06<br />
1.E-09<br />
1.E-12<br />
1.E-15<br />
1.E-18<br />
1.E-21<br />
1.E-24<br />
1.E-27<br />
10 20 30 40 50 60 70 80 90 100<br />
Wavenumber [cm-1]<br />
1 10 100 1000 10000 100000<br />
Wavenumber [cm-1]<br />
Figure 4-27 - Transmission characteristics of prototype 350-µm photometer filter chain<br />
The <strong>SPIRE</strong> dichroics are implemented as capacitative low-pass edge filters placed at an angle to the beam.<br />
To maintain the sharpness of the edge, the angle of incidence is set at < 25 o . Figure 4-28 shows typical<br />
transmission and reflection profiles for such a dichroic.<br />
84
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