Low-cost, compact Fiber-Optic Gyroscope for super-stable Line-of-Sight stabilization

This paper presents a new Interferometric Fiber Optic Gyroscope (IFOG) optimized for Line of Sight (LoS) stabilization being developed by IFOS and its prime subcontractors InFiber Technology and Optiphase under sponsorship of AFRL as a Phase II SBIR program. To date IFOS designed, built and tested five prototypes. Four gyros were delivered to Lockheed Martin (LM) for further testing. The design is based on an innovative approach that enables production of a small, low cost gyro with excellent noise and bandwidth (BW) characteristics. The development is aimed at achieving sensor volume less than 5 cubic inches (φ2.0 × 1.5) with cost less than several thousand dollars per axis. The new IFOS gyro uses an open-loop configuration, utilizing small diameter fiber with new all-digital signal processing. The optics is integrated using all-fiber approach that leads to highly flexible and lower cost implementation. The gyro is configured as a "split gyro" (distributed architecture), where the light source, electronics and receiver are integrated in an external package, and the sensor head is integrated in robust and environmentally rigid package. The dimensions of the present sensor-head prototype are φ2.7 × 2 (11.5 cubic inches), using single mode fiber (SMF) for low cost. The gyro data rate is very large and can be as high as the modulation frequency (> 40 kHz). We have shown that the Angle White Noise (AWN) at high frequencies is not flattening out and extremely-high-BW low-noise operation is possible. To date we measured Angle Random Walk (ARW) <; 0.0022 deg/rt-hr and demonstrated angle noise density <; 10
^-11
(arc-sec)
²
/Hz at 10 kHz and integrated angle noise <; 100 nano-radians at 2 Hz to 10 kHz BW window. The SMF gyro demonstrated <; 0.02 deg/hr flicker limit and <; 0.2 deg/hr long term in run bias stability.