RLG (Ring Laser Gyroscope) is a type of gyroscope used in inertial navigation systems (INS) to measure angular velocity with high precision and stability. Unlike mechanical gyroscopes, an RLG operates using laser interference instead of moving parts, making it highly reliable, durable, and resistant to external disturbances.
How Does an RLG Work in INS?
Laser Beam Generation – Two laser beams travel in opposite directions inside a closed, triangular or square-shaped optical cavity.
Sagnac Effect – When the system rotates, the effective path length for the laser beams changes, causing a phase shift due to the Sagnac effect.
Interference Pattern Measurement – The phase shift between the two laser beams creates an interference pattern, which is detected and converted into angular velocity data.
INS Integration – The measured angular velocity is integrated over time to determine orientation and position in GPS-denied environments.
Applications of RLG in INS
✔ Aerospace & Aviation – Used in aircraft navigation systems for precise attitude control and flight stability.
✔ Maritime & Submarine Navigation – Critical for submarines and naval vessels operating without GNSS.
✔ Military & Defense – Employed in missile guidance, tanks, and naval warships where robust and accurate navigation is required.
✔ Spacecraft & Satellites – Ensures accurate positioning and attitude control in deep space missions.
Advantages of RLG in INS
✔ High Precision & Stability – Offers exceptional accuracy with minimal drift over time.
✔ No Moving Parts – Unlike mechanical gyroscopes, RLGs are wear-free and highly durable.
✔ Resistant to External Forces – Less affected by vibrations, shocks, and temperature variations compared to traditional gyroscopes.
Challenges of RLG in INS
✔ Lock-In Effect – At very low rotation rates, laser beams may synchronize, causing measurement errors (mitigated using dithering techniques).
✔ Higher Cost – RLG systems are more expensive compared to MEMS gyroscopes.
✔ Complex Electronics – Requires precise optical alignment and signal processing for accurate results.
