MIL-DTL-83526C
4.8 Optical conformance test methods. Cladding shall be removed. In those cases where the fiber
coating does not adequately perform this function, an equilibrium mode simulator and cladding mode
stripper shall be installed between the source and connector (in that order) as well as between the
connector and detector (in that order) when making optical measurements. A one kilometer section of
fiber may be substituted for the equilibrium mode simulator and cladding mode stripper between the
source and connector if desired. In connectors with one, two, or three optical channels, optical
measurements shall be made in rapid succession on each channel. Unless otherwise specified herein, in
connectors with four or more channels, optical measurements shall be made in rapid succession on three
randomly selected channels.
4.8.1 Insertion loss (see 3.10.1). The initial insertion loss of multimode connectors shall be measured
in accordance with method A of TIA/EIA-455-34, using both 70/70 and overfill launch conditions. For
subsequent insertion loss tests, 70/70 launch conditions or equivalent shall be used. The insertion loss of
single mode connectors shall be measured in accordance with method B of TIA/EIA-455-34.
4.8.2 Discontinuities (see 3.10.2). The connector shall be tested in accordance with TIA/EIA-455-32.
The optical termini of the connector shall be connected through a minimum of 4 meters of optical test
cables to an appropriate optical signal source and detector. Unused termini shall be capped. The source
shall produce a constant level, static signal easily detected by the detector. The output of the detector
shall be monitored for discontinuities while the connector is subjected to a mechanical or environmental
test exposure. The detector and monitoring equipment shall possess sufficient sensitivity and high
frequency response to detect discontinuities in the optical signal. The monitoring equipment shall include
transient capture capability (such as provided by an electronic counter or by an oscilloscope with an
adjustable sweep trigger and oscilloscope camera).
4.8.3 Analog modulation (see 3.10.3). The optical termini of the connector shall be connected through
a minimum of 4 meters of optical cables to an optical signal source and detector. Unused termini shall be
capped. The source shall produce a constant level, static signal easily detected by the detector. The
output of the detector shall be monitored for analog modulation while the device under test is subjected to
vibration (see 4.9.23). The detector and monitoring equipment shall possess sufficient sensitivity and
frequency response to discern analog modulation at the acceptance level. The monitoring equipment
shall include signal recording capability (such as provided by a triggerable oscilloscope and an
oscilloscope camera).
4.8.4 Crosstalk (see 3.10.4). The termini of the connector shall be connected to a minimum of 4
meters of optical test cables or opaquely capped as appropriate. The input to one optical channel (the
active channel) shall be connected via its test cable to an optical signal source, the signal of which shall
be either continuous or amplitude modulated. The output port(s) of the other channels (passive
channel(s)) shall be connected to test cable(s). The other input ports shall be opaquely capped. The
output signal power from both the active and passive channels shall be measured. When there is more
than one passive channel, the output of all passive channels shall be summed. This test shall be
repeated, making each remaining input port the active channel.
4.8.5 Change in optical transmittance (see 3.10.5). The change in optical transmittance shall be
measured in accordance with TIA/EIA-455-20. The use of a reference fiber to evaluate the change in
optical transmittance due to exposure of the cable to the environmental tests is optional. Measurements
shall be made before and after environmental tests, and during tests per table VII.
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