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 |
<< Previous | Next >> |
Effects of the space environment on infrared filters and materials
Contact us
- Email:
irfilters@reading.ac.uk - Telephone:
+44 (0) 118 378 8224