Research Of The Off-axis Fiber-optic Rotary Joint

In recent years, with the rapid development of optical fiber technology, fiber-opticrotary joint has been used in military defense, industrial control, energy and medicalfields widely. But when the shaft of rotating parts is occupied, the general fiber-opticrotary joint is not applicable. This paper describes the research progress of fiber-opticrotary joint and proposes the off-axis fiber-optic rotary joint, which consists of twocollimator lenses and realizes the off-axis rotating connection, basing on analyzing theadvantages and disadvantages of fiber-optic rotary joint. The main work includes:1. With Gaussian beam coupling theory, the main influence factors of the insertionloss of the off-axis fiber-optic rotary joint are analyzed, theoretically. The theoreticalcalculation formulas for the insertion loss with axial distance, axial angle andtransversal dislocation are achieved.2. Building the static and dynamic experiments for the insertion loss of off-axisfiber-optic rotary joint, experiment verifies the relationship between insertion loss andits influence factors. The method to improve the duty cycle is obtained by analyzing thecoupling signals of off-axis fiber optic rotary joint.3. Using F-P filter to realize the wavelength demodulation of coupling signals, thenpeak detection is carried out to deal with the demodulated signal so that thedemodulated information will be displayed visually.4. Describing the sensor characteristics of fiber Bragg grating with temperature,strain and pressure. And packaging the small size fiber Bragg grating temperature sensor.Proposing the measurement method for detecting the temperature on the rotating partsbased on the off-axis fiber-optic rotary joint and fiber Bragg grating when the shaft isoccupied, and experiment verifies the feasibility of the temperature measurementmethod.