MIL-PRF-49291D
4.7.3.6 Chromatic dispersion. The chromatic dispersion characteristics shall be determined in
accordance with TIA-455-175 using Methods A, B, or C for Type I and Type II fibers (see 3.6.6). If an
overfill launch is not utilized for Type I (multimode) fiber, a single mode launch shall be utilized and the
measured results corrected using the procedure in Appendix A. If Type I (multimode) fiber is measured
on chromatic dispersion instrumentation with a single mode launch condition, then conversions shall be
performed on measurement data per appendix A.
4.7.3.7 Cutoff wavelength (for type II fiber only). The cutoff wavelength of Type II fibers shall be
4.7.3.8 Transient attenuation (for type I fiber only). The transient attenuation shall be measured as
follows. The attenuation shall be measured in accordance with TIA-455-78 method B using overfilled
launch conditions without mode filter or cladding mode strippers. Then the attenuation of the sample
shall be measured in accordance with TIA-455-78, method B. The transient attenuation is defined as the
difference in the two attenuation values obtained (see 3.6.8).
4.8 Environmental inspections.
4.8.1 Thermal shock. The fibers shall be tested in accordance with TIA-455-71 using test condition A-0
(see 3.7.1). The temperature extremes shall be the specified storage temperature extremes (see 3.1).
The change in optical transmittance shall be measured after the test.
4.8.2 Temperature humidity cycling. The fibers shall be tested in accordance with MIL-STD-1678-3
measurement 3302.
measurement 3301.
4.8.4 Life aging. The fibers shall be tested in accordance with MIL-STD-1678-3 measurement 3303.
Temperature shall be +95°C +3°C, ---0°C. The time shall be 500 hours. The frequency of change in
optical transmittance measurements shall be daily (see 3.7.4).
4.8.5 Fluid immersion aging. The fiber shall be immersed in the specified fluids(s) for the duration and
temperature as specified (see 3.1) in accordance with TIA-455-74. The samples shall be dried or drained
as recommended in the test procedure. After a minimum 24 hour period, the samples shall be tested in
4.8.6 Nuclear radiation resistance (see 3.7.6). The fibers shall be tested for susceptibility to gamma
radiation, prompt gamma radiation, and neutron radiation in accordance with TIA/EIA-455-64 (see 3.7.6).
Test conditions shall be as specified (see 3.1). Optical characteristics shall be verified at the low
operating temperature and at +25°C. The change in optical transmittance shall be measured during and
after the test. If the change in optical transmittance at +25°C is greater than the change in optical
transmittance at the low operating temperature, the fiber shall be tested at the high operating
temperature.
4.8.7 Fungus resistance (see 3.7.7). Fibers composed of materials not listed as fungus inert in
4.8.8 Dynamic tensile strength. Fifteen fiber specimens shall be preconditioned in 50 percent relative
humidity for a minimum of 12 hours. The specimens shall then be tested in a 50 percent RH environment
in accordance with TIA-455-28. The mean fracture strength and Weibull modulus shall be calculated (see
3.7.8).
4.8.9 Storage temperature (see 3.7.9). The fibers shall be tested in accordance with the conditions
and procedure specified in table VI. Change in optical transmittance shall be measured before and after
each 120 hour temperature plateau.
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