Lenses that are exposed to high vibration or high-G shocks or are inaccessible and simply must not fail. A ruggedized lens starts as a standard lens that:
is completely disassembled
has thread-locking compound placed on all its internal threads and retaining rings
has its adjustable iris replaced with an application-specific fixed iris (optional)
is reassembled, tested, and shipped with a certificate of compliance if requested.