Interferometry

Interferometry in inertial navigation refers to the use of wave interference principles (typically light or radio waves) to measure precise motion, orientation, and distance. It is commonly applied in high-precision gyroscopes, such as Fiber Optic Gyroscopes (FOG) and Ring Laser Gyroscopes (RLG), which are essential for aerospace, defense, and submarine navigation.

How Interferometry Works in INS?

  1. Wave Propagation – A light beam is split into two and sent in opposite directions within an optical fiber or ring laser cavity.

  2. Sagnac Effect Detection – When the system rotates, the interference pattern of the recombined light changes, allowing precise angular velocity measurement.

  3. Integration with INS – The measured rotation is used to calculate orientation and navigation data.

Applications of Interferometry in Inertial Navigation

Fiber Optic Gyroscopes (FOG) – Uses optical fibers to measure rotation with high accuracy and no moving parts.

Ring Laser Gyroscopes (RLG) – Employs laser interference in a closed cavity to achieve low-drift angular velocity measurement.

Precision Navigation in GPS-Denied Environments – Used in submarines, spacecraft, and military systems where GNSS is unavailable.

Advantages of Interferometry-Based INS

High Sensitivity & Accuracy – Measures extremely small rotational changes.

No Moving Parts – Increases reliability and longevity compared to mechanical gyroscopes.

Immune to Electromagnetic Interference (EMI) – Ideal for military and aerospace applications.