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Filter experiment construction

In order to obtain a representative assessment of the effects of exposure to the space environment of the infrared filters and materials flown on the LDEF, a total of 46 components were distributed between two tray locations, as illustrated in Figure 12. One location was positioned to be continuously facing Earth (G12) at an angle of 90.8° off the RAM incidence angle (Figure 14), whilst the other location tray was positioned to continuously view space on the leading edge of the vehicle (B08) at 38.1° off the RAM incidence angle (Figure 15). Each tray was designed to maximise the exposure of the full aperture to the complete range of space radiation environments and temperature excursions.


Figure 12, Location of exposed filter experiment trays

The filters were each housed in chromic anodised BS.L93 aluminium alloy circular holders and mounted in 6061-T6 chromic anodised aluminium alloy base plates. Thermal contact was ensured by Pb washers located either side of the substrate. Induced pressure differentials across the substrates were relieved by a hole in each backing piece to prevent substrate flexing or deformation. Figure 13 shows the substrate holder construction.


Figure 13, Filter holder assembly

Figure 14, Earth facing tray G12
Earth Facing Exposed Materials (G12)
Holder No. Substrate Material Coating Materials Filter Type
5 MgF2 - Uncoated Substrate
6 CaF2 - Uncoated Substrate
7 KRS-5 - Uncoated Substrate
8 KRS-6 - Uncoated Substrate
13 KRS-5 As2S3 /KRS-5 61-Layer Quarter Wave Stack
15 CdTe - Uncoated Substrate
16 KRS-6 ZnS/KRS-5 - ZnSe/KRS-5 33-Layer Quarter Wave Stack
18 KRS-5 CdTe/KRS-5 - As2S3/KRS-5 61-Layer Quarter Wave Stack
21 Ge PbTe/ZnS 7.35µm 5% L-Spaced THW BP
22 Ge PbTe/ZnS 5.74µm 6% L-Spaced THW BP
26 Ge PbTe/ZnS 7.35µm 5% L-Spaced THW BP
29 Ge PbTe/ZnS 14.5µm 0.7% L-Spaced FP BP
32 Ge PbTe/ZnS 14.5µm 0.7% Split-Spacer FP BP
35 Ge PbTe/ZnSe 14.5µm 0.7% Split-Spacer FP BP
36 Ge PbTe/ZnS 14.5µm 0.7% L-Spaced FP BP
38 Ge PbTe/ZnS 11µm 10% H-Spaced THW BP
40 Ge PbTe/ZnS 15µm 10% L-Spaced THW BP
41 Ge PbTe/ZnS 15µm 10% L-Spaced THW BP
44 ZnSe PbF2/PbF2 10.6µm Single Wavelength AR
45 Ge PbTe/ZnS 9.24µm 2% H-Spaced DHW BP

Figure 15, Leading edge tray B08
Space Facing Exposed Materials (B08)
Holder No. Substrate Material Coating Materials Filter Type
1 MgF2 - Uncoated Substrate
2 CaF2 - Uncoated Substrate
3 KRS-5 - Uncoated Substrate
4 KRS-6 - Uncoated Substrate
9 CdTe - Uncoated Substrate
10 Si - Uncoated Substrate
11 Y-Quartz - Uncoated Substrate
12 Z-Quartz - Uncoated Substrate
14 KRS-5 As2S3 / KRS-5 61-Layer Quarter Wave Stack
17 KRS-6 ZnSe / KRS-5 - ZnS / KRS-5 33-Layer Quarter Wave Stack
19 KRS-5 CdTe / KRS-5 - As2S3 / KRS-5 61-Layer Quarter Wave Stack
23 Ge - Uncoated Substrate
24 Al2O3 Ge / SiO 4.45µm 3.5% 2L:1H Quarter Wave Stack
25 Al2O3 Ge / SiO 4.45µm 3.5% 2L:1H Quarter Wave Stack
27 Ge PbTe / ZnS 14.5µm 0.7% L-Spaced Fabry-Pérot BP
28 Ge PbTe / ZnS 14.5µm 0.7% L-Spaced Fabry-Pérot BP
30 Ge PbTe / ZnS 14.5µm 0.7% Split-Spacer Fabry-Pérot BP
31 Ge PbTe / ZnS 14.5µm 0.7% Split-Spacer Fabry-Pérot BP
33 Ge PbTe / ZnSe 14.5µm 0.7% Split-Spacer Fabry-Pérot BP
34 Ge PbTe / ZnSe 14.5µm 0.7% Split-Spacer Fabry-Pérot BP
37 Ge PbTe / ZnS 8-12µm Long-Wave Pass Edge Filter
39 Ge PbTe / ZnS 11µm 10% H-Spaced THW BP
42 Ge PbTe / ZnS 10.6µm 2.5% H-Spaced DHW BP
43 Ge PbTe / ZnS 10.6µm 2.5% H-Spaced DHW BP
46 Al2O3 - Uncoated Substrate
47 Si SiO 4.4µm Single Wavelength AR
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Effects of the space environment on infrared filters and materials