Fibre Optic Rotary Joints: Complete Guide

In today’s high-speed digital world, the need for seamless data transmission in challenging environments is greater than ever. Fibre optic rotary joints (FORJs) play a crucial role in enabling continuous data transfer between rotating and stationary systems without signal dropout. This blog will guide you through what a fibre optic rotary joint is, how it works, the different types available, and the numerous applications where they are used.

What is a fibre optic rotary joint?

A fibre optic rotary joint is a device that transmits data through a rotating interface. This allows systems that need to spin or rotate whilst maintaining flawless communications, like radars or medical scanners, stay connected and keep sending data smoothly.

How do fibre optic rotary joints work? 

Fibre optic rotary joints work by guiding light signals out of, and then back into, micron-scale optical fibres that are coupled at a rotary interface. When the two sides of the joint rotate, the light is transmitted via optical components such as lenses or prisms that align the optical path as needed.

Key to the functioning of a FORJ is the precise alignment of the fibre optics to prevent drop-out, attenuation, or distortion of the signal as it passes through the rotary interface. To achieve and maintain this alignment requires thorough design, precision manufacturing, expertise in assembly and stringent process quality control. 

Types of fibre optic rotary joints

There are many variations of fibre connector type, multiple fibre types in common use and many different application environments requiring loss-free data transfer. BGB’s connector and fibre type guides give more technical detail about types of fibre and connectors and their main uses. 

Single-Channel FORJs

Our single channel FORJs are constructed from stainless steel and are manufactured for all the main fibre types. Download our datasheets to find out more. Single channel FORJs are ideal for converting single or multiple channels of electrical signals (e.g. ethernet) into optical signals before they pass from a rotating side to a non-rotating side of a machine or application. 

Multi-Channel FORJs

Our range of Multimode FORJs perform the same job as single-channel but allow there to be parallel and separate channels.These are especially useful where separate physical local area networks (LAN) are required for security reasons or for immediate signal redundancy/back-up. 

What applications are they used for? 

Fibre optic rotary joints are used in a wide range of industries and applications where rotating platforms require uninterrupted data transfer. Key areas of application include:

Wind Turbines

These joints are essential in wind turbines to transmit data from the rotating blades to stationary control systems. They are also used in other parts of the energy sector, such as turbine generators in nuclear plants, as well as tidal turbines.

Drones, Remotely Operated Vehicles and Robotics

FORJs are used in tethered drones and remotely operated vehicles to transmit large video or data to the main hub via an umbilical cable attached to a cable reel, rotating joint or arm. They aid the transmittance of high-bandwidth video and data signals through the tethered or rotating connections, ensuring a reliable data link essential for secure communications and high-quality real-time video data critical for surveillance, inspection, or other specialised drone operations.

Radar

FORJs are used in radars where large amounts of surveillance data is captured over 360° and needs to be passed without loss back to a stationary display or interrogation unit. These systems are used on land, in the air and at sea in defence, commercial, and civil surveillance where threats, objects, or even persons in distress need to be identified. 

Benefits of fibre optic rotary joints 

The use of fibre optic rotary joints brings several advantages, making them indispensable in modern technology:

1. High-Speed Data Transmission
   FORJs allow for fast and high-bandwidth data transfer without the interference and noise issues that can affect traditional electrical connections.

2. Secure
   Unlike wireless technologies, it is not possible to interrupt or listen in to fibre optic communications without interfering with the actual fibre cable. 

3. Uninterrupted Rotation
   The ability to rotate 360 degrees continuously while maintaining signal integrity makes these joints ideal for applications requiring constant motion.

4. Low Signal Loss
   Fibre optics inherently have very low signal loss compared to copper wires, making FORJs a great solution for long-distance or high-frequency data transfer.

5. Compact and Lightweight
   Fibre optic technology is lightweight and compact, making it ideal for applications where space and weight are critical, such as in aerospace or medical devices.

6. Immune to Electromagnetic Interference (EMI)
   Fibre optic systems are immune to EMI, ensuring that data transfer remains unaffected by external electromagnetic fields, a crucial benefit in many industrial and defence applications.

BGB FORJ Solutions 

At BGB, we provide a range of FORJ products, and these can be built into bespoke slip ring solutions designed to cater for business-specific requirements. 

To find out more about the FORJ products provided by BGB, download our FORJ brochure or get in touch with our experts to find the right solution for you.