How it works
Expanded beam fiber optic connectors utilize lenses to expand and collimate the light emitted from the fiber. The collimated beam is transmitted through the air gap to the mating connector, where the light is collected by a second lens and focused into a second optical fiber to complete the connection.
Advantages of expanded beam
Extended beam fiber optic connectors offer several advantages over physical contact connectors in harsh environments.
When the physical contact connector is unmated, the highly polished ferrule ends are exposed to dirt and debris that can pick up on the fiber end face. Then, when the connectors mate, these debris can damage the sub-micron polished surface and degrade the connector's optical performance. This is especially dangerous in high vibration applications. The expanded beam connector is a non-contact design with a lens that completely seals the fiber and expands the beam diameter. The air gap created between the mating lenses ensures that any debris present on the lenses will not cause damage during operation or vibration, greatly increasing the connector's reliability in harsh conditions.
Additionally, expanded beam connectors have greater tolerance for misalignment caused by shock and vibration. They are easier to maintain and clean.
Design description
Standardization
MIL-DTL-83526 is a military specification that describes the characteristics, performance, and testing standards for environmentally resistant fiber optic circular connectors with non-polar interfaces. The standard covers the use of low-loss fiber optic cable connectors in terrestrial fiber optic data transmission systems that are robust enough for military field applications.
Touch
Beam expansion is a contactless fiber optic technology. Light passes through the small gap between the two lenses.
Termination
Expanded beam connectors can be pre-terminated at the factory or terminated in the field using standard epoxy polishing techniques.
Model
Extended beam connectors can be single-mode (core size is approximately 8.3 μm; light travels in a single path along the fiber) or multimode (core size ranges from 50 μm to 62.5 μm; light travels in various paths through the fiber). They typically offer fiber counts from 2 to 16 fibers.