Optical Fiber Proximity Sensor
Passive fiber-optic proximity switch that returns reflected light when a magnet brings a field of 1000 gauss or more to the sensor.
Technical overview
A Faraday-effect point sensor read over a single-core single-mode fiber by an OTDR. With no magnetic field present the incident light does not return down the fiber; with 1000 gauss or more applied it comes back as reflected light on the same fiber, so the OTDR sees a state change at that position. Shinkosha lists a small variant of 6 mm diameter by 20 mm long with no waterproof structure, a sensor-and-magnet integrated variant, and a variant with the magnet built into the case that triggers on a magnetic target plate such as SUS430.
Features
- Sensor uses no electricity and needs no data transmitter
- Scattered sensors are read collectively in near real time, once every 5 seconds
- Usable in adverse environments such as mountains, coasts and sewers
- Already deployed in electricity, harbour and river management applications
- Interrogated with off-the-shelf OTDR units rather than a proprietary detector
- Triggers on an applied field of 1000 gauss or more
- Small variant 6 mm diameter x 20 mm long, without waterproof structure
- Sensor-and-magnet integrated variant available
- Magnet-in-case variant that senses a magnetic target plate such as SUS430
Specifications
| Parameter | Value |
|---|---|
| Trigger threshold, applied magnetic field | 1000 or more gauss |
| Fiber type (Faraday sensor series) | Single core, single mode |
| Small type dimensions | 6 (dia.) x 20 (length) mm |
| Small type waterproofing | None |
| Target material, magnet-in-case variant | Magnetic plate, e.g. SUS430 |
| System measurement interval (OTDR system) | Once every 5 seconds |
Applications
- Open/close detection of sluiceways and sluice pipes
- Open/close detection of tide gates
- Open/close detection in explosion-proof areas
- Open/close detection in electrically noisy environments such as power facilities
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