Reduced minimum configuration interferometric fiber optic gyroscope with simplified signal processing electronics

Abstract

An interferometric fiber optic gyroscope (IFOG) system includes a fiber sensing coil and a semiconductor or rare-earth doped fiber light source emitting light with an associated light source intensity. The source has a front output and back output. An optical coupler is attached to the front output for receiving said light from said light source and the coupler creates two substantially equal intensity light beams for simultaneous transmission into the sensing coil said coupler attached to the coil. The fiber sensing coil supplies return light to the coupler from said equal intensity light beams and the coupler combines and interferes the return light into a combined light beam. An optical phase modulator has a phase modulation amplitude, and the modulator coupled to the coil. An oscillator is coupled to the modulator and produces a periodic voltage which controls the phase modulation amplitude. The combined light signal is transmitted through the light source and received by the detecting means coupled to said light source at the back output. Light detection means detect and convert the combined light beam into an electrical current. An electrical amplifier is coupled to the detector for converting said current into an electrical voltage. Alternating current voltage amplitude controller means is coupled to the amplifier, and controls the associated light source intensity. Electrical signal processing means is coupled to the amplifier and processes the voltage and provides an output signal proportional to the angular rotation rate input of the sensing coil.